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  Subjects -> CHEMISTRY (Total: 844 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (597 journals)
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CHEMISTRY (597 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 5)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 25)
ACS Catalysis     Full-text available via subscription   (Followers: 25)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 15)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 32)
ACS Nano     Full-text available via subscription   (Followers: 160)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 16)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 4)
Acta Scientifica Naturalis     Open Access  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 6)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 43)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 50)
Advances in Chemical Science     Open Access   (Followers: 11)
Advances in Chemistry     Open Access   (Followers: 9)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 14)
Advances in Drug Research     Full-text available via subscription   (Followers: 21)
Advances in Enzyme Research     Open Access   (Followers: 4)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 12)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 15)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 37)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 13)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 13)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 3)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 61)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 13)
American Journal of Chemistry     Open Access   (Followers: 23)
American Journal of Plant Physiology     Open Access   (Followers: 12)
American Mineralogist     Full-text available via subscription   (Followers: 8)
Anadolu University Journal of Science and Technology     Open Access  
Analyst     Full-text available via subscription   (Followers: 41)
Angewandte Chemie     Hybrid Journal   (Followers: 115)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 160)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 2)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 9)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 5)
Applied Spectroscopy     Full-text available via subscription   (Followers: 24)
Applied Surface Science     Hybrid Journal   (Followers: 22)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 2)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 4)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 8)
Biochemistry     Full-text available via subscription   (Followers: 207)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 8)
Bioinspired Materials     Open Access   (Followers: 2)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 9)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 92)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 81)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 1)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal  
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 27)
Carbon     Hybrid Journal   (Followers: 62)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 5)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 6)
Cellulose     Hybrid Journal   (Followers: 4)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription  
ChemCatChem     Hybrid Journal   (Followers: 6)
Chemical and Engineering News     Free   (Followers: 11)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 63)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 20)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 17)
Chemical Reviews     Full-text available via subscription   (Followers: 122)
Chemical Science     Open Access   (Followers: 18)
Chemical Technology     Open Access   (Followers: 11)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 52)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 4)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 29)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry - A European Journal     Hybrid Journal   (Followers: 109)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 12)
Chemistry and Materials Research     Open Access   (Followers: 14)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 4)
Chemistry in Education     Open Access   (Followers: 2)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 43)
Chemistry of Materials     Full-text available via subscription   (Followers: 138)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 8)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 6)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 5)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 8)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 10)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 9)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription  
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 4)
Crystal Structure Theory and Applications     Open Access   (Followers: 2)
CrystEngComm     Full-text available via subscription   (Followers: 7)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 7)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 7)
Current Science     Open Access   (Followers: 28)
Dalton Transactions     Full-text available via subscription   (Followers: 17)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 1)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 2)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
EDUSAINS     Open Access  
Elements     Full-text available via subscription   (Followers: 1)
Environmental Chemistry     Hybrid Journal   (Followers: 5)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 2)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 3)

        1 2 3 | Last

Journal Cover Advanced Functional Materials
  [SJR: 4.682]   [H-I: 156]   [43 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
   Published by John Wiley and Sons Homepage  [1598 journals]
  • Masthead: (Adv. Funct. Mater. 32/2016)
    • PubDate: 2016-08-22T09:07:34.87088-05:0
      DOI: 10.1002/adfm.201670206
       
  • Stimuli‐Responsive Liquid Marbles: Controlling Structure, Shape,
           Stability, and Motion
    • Abstract: “Liquid marbles” are liquid‐in‐gas dispersed systems stabilized by hydrophobic solid particles adsorbed at the gas‐liquid interface. The structure, stability and movement of these liquid marbles can be controlled by external stimuli such as pH, temperature, light, magnetic and electric fields, ultrasonic, mechanical stress and organic solvents. Stimuli‐responsive modes can be categorized into five classes: (i) liquid marbles whose stability can be controlled by adsorption/desorption of solid particles to/from liquid surfaces, (ii) liquid marbles that can open and close their particle‐coated surface by moving particles to and from the gas‐liquid surface, (iii) liquid marbles that can move, (iv) liquid marbles that can change their shape and (v) liquid marbles that can be split. As a result of these stimuli‐responsive characteristics, liquid marbles offer potential in the areas of controlled encapsulation, delivery and release. Liquid marbles are liquid‐in‐gas dispersed systems stabilized by solid particles adsorbed at the gas‐liquid interface. The recent progress made in stimuli‐responsive liquid marbles, whose structure, stability and movement can be controlled by external stimuli such as pH, temperature, light, magnetic and electric fields, ultrasonic, mechanical stress and organic solvents, is reviewed.
      PubDate: 2016-08-22T05:37:02.496488-05:
      DOI: 10.1002/adfm.201603223
       
  • Optical Properties of Hybrid Organic‐Inorganic Materials and their
           Applications
    • Abstract: Research on hybrid inorganic‐organic materials has experienced an explosive growth since the 1980s, with the expansion of soft inorganic chemistry based processes. Indeed, mild synthetic conditions, low processing temperatures provided by “chimie douce” and the versatility of the colloidal state allow for the mixing of the organic and inorganic components at the nanometer scale in virtually any ratio to produce the so called hybrid materials. Today a high degree of control over both composition and nanostructure of these hybrids can be achieved allowing tunable structure‐property relationships. This, in turn, makes it possible to tailor and fine‐tune many properties (mechanical, optical, electronic, thermal, chemical…) in very broad ranges, and to design specific multifunctional systems for applications. In particular, the field of “Hybrid‐Optics” has been very productive not only scientifically but also in terms of applications. Indeed, numerous optical devices based on hybrids are already in, or very close, to the market. This review describes most of the recent advances performed in this field. Emphasis will be given to luminescent, photochromic, NLO and plasmonic properties. As an outlook we show that the controlled coupling between plasmonics and luminescence is opening a land of opportunities in the field of “Hybrid‐Optics”. This review reports the latest works on hybrid optical materials. It gives an insight in the state‐of‐the‐art in the field of hybrid materials devoted to optics and in particular the relationship between the different types of structure, the organic‐inorganic interfaces and the final properties of the systems.
      PubDate: 2016-08-22T05:36:48.993076-05:
      DOI: 10.1002/adfm.201602730
       
  • Donor and Acceptor Unit Sequences Influence Material Performance in
           Benzo[1,2‐b:4,5‐b′]dithiophene–6,7‐Difluoroquinoxaline
           Small Molecule Donors for BHJ Solar Cells
    • Abstract: Well‐defined small molecule (SM) donors can be used as alternatives to π‐conjugated polymers in bulk‐heterojunction (BHJ) solar cells with fullerene acceptors (e.g., PC61/71BM). Taking advantage of their synthetic tunability, combinations of various donor and acceptor motifs can lead to a wide range of optical, electronic, and self‐assembling properties that, in turn, may impact material performance in BHJ solar cells. In this report, it is shown that changing the sequence of donor and acceptor units along the π‐extended backbone of benzo[1,2‐b:4,5‐b′]dithiophene–6,7‐difluoroquinoxaline SM donors critically impacts (i) molecular packing, (ii) propensity to order and preferential aggregate orientations in thin‐films, and (iii) charge transport in BHJ solar cells. In these systems (SM1‐3), it is found that 6,7‐difluoroquinoxaline ([2F]Q) motifs directly appended to the central benzo[1,2‐b:4,5‐b′]dithiophene (BDT) unit yield a lower‐bandgap analogue (SM1) with favorable molecular packing and aggregation patterns in thin films, and optimized BHJ solar cell efficiencies of ≈6.6%. 1H‐1H DQ‐SQ NMR analyses indicate that SM1 and its counterpart with [2F]Q motifs substituted as end‐group SM3 possess distinct self‐assembly patterns, correlating with the significant charge transport and BHJ device efficiency differences observed for the two analogous SM donors (avg. 6.3% vs 2.0%, respectively). Changing the sequence of donor and acceptor units along the π‐extended backbone of benzo[1,2‐b:4,5‐b′]dithiophene–6,7‐difluoroquinoxaline small molecule (SM) donors critically impacts (i) molecular packing, (ii) propensity to order and preferential aggregate orientations in thin‐films, and (iii) charge transport in bulk‐heterojunction (BHJ) solar cells. The lower‐bandgap analogue (SM1) achieves distinct local packing and aggregation patterns in thin films, and optimized BHJ solar cell efficiencies of ≈6.6%.
      PubDate: 2016-08-22T01:29:36.227213-05:
      DOI: 10.1002/adfm.201602162
       
  • Complementarity and Uncertainty in Intrafibrillar Mineralization of
           Collagen
    • Abstract: Biomineralization in vertebrates is a ubiquitous and tightly regulated process which creates hierarchical structures for the skeleton. Because of the lack of understanding and applicability of cell‐based or biological systems to achieve intrafibrillar mineralization, scientists adopted various in vitro methods to elucidate the mechanism of intrafibrillar mineralization. In this article, biomimetic intrafibrillar mineralization of collagen in its wide ramifications is reviewed. It is intriguing how prevailing intrafibrillar mineralization mechanisms derived from two potentially discordant crystallization philosophies were equally adept, depending on the experimental context, at theorizing the formation of calcium phosphate within a fibrillar template. This complementarity is not unique to biomineralization and has precedence in other fundamental physical interpretations. A new intrafibrillar mineralization process based on the use of polycationic process‐directing agent added uncertainty to the use of existing mechanisms in accounting for the observations. Polycation directed intrafibrillar mineralization of collagen adds complementarity and uncertainty to the currently available mechanisms on collagen biomineralization, including those associated with ion‐based and particle‐based crystallization theories. The seemingly discordant mechanisms proposed for intrafibrillar mineralization, despite their evolution from quite different contexts, represent different means in achieving the same end.
      PubDate: 2016-08-22T01:29:07.859114-05:
      DOI: 10.1002/adfm.201602207
       
  • Liquid‐Infused Smooth Coating with Transparency,
           Super‐Durability, and Extraordinary Hydrophobicity
    • Authors: Mizuki Tenjimbayashi; Ryo Togasawa, Kengo Manabe, Takeshi Matsubayashi, Takeo Moriya, Masatsugu Komine, Seimei Shiratori
      Abstract: Liquid‐infused coatings are because of their fluidity of considerable technological importance for hydrophobic materials with multifunctional properties, such as self‐healing, transmittance, and durability. However, conventional coatings absorb viscous liquid into their sponge‐like structured surface, causing uncontrollable liquid layer formation or liquid transport. In addition, a hydrophobic‐liquid‐retained surface can cause instability and lead to limitation of the hydrophobicity, optical properties, and flexibility due to liquid layer evaporation. Here, we report a strategy for controllable liquid‐layer formation on smooth surfaces (R rms < 1 nm) by π ‐electron interactions. Using this technology, superoleophilic wetting of decyltrimethoxysilane results in the design of a surface with π ‐interaction liquid adsorption, smoothness, and hydrophobicity (SPLASH), that shows extraordinary hydrophobicity (CAH = 0.75°), and stable repellence for various water‐based solutions including micrometer‐sized mist. The smoothness of the solid under a liquid layer enabled the SPLASH to exhibit stable hydrophobicity, transparency (>90%), structure damage durability and flexibility, regardless of the liquid layer thickness by bending or evaporation. Furthermore, the patterned π ‐electrons' localization on the smooth coating enables controlled liquid‐layer formation and liquid transport. This strategy may provide new insights into designing functional liquid surfaces and our designed surface with multifunctional properties could be developed for various applications. Liquid‐infused coatings are of considerable technological importance as multifunctional hydrophobic materials. However, the roughness of the underlayer coating causes instability and inflexibility and limits the hydrophobicity or optical properties. Here, we report a liquid‐infused smooth surface (R rms < 1 nm) that shows extraordinary hydrophobicity (contact angle hysteresis
      PubDate: 2016-08-22T01:28:01.300704-05:
      DOI: 10.1002/adfm.201602546
       
  • A Composite Fabrication Sensor Based on Electrochemical Doping of Carbon
           Nanotube Yarns
    • Abstract: This work shows evidence of conventional liquid and polymer molecules doping macroscopic yarns made up of carbon nanotubes (CNT), an effect that is exploited to monitor polymer flow and thermoset curing during fabrication of a structural composite by vacuum infusion. The sensing mechanism is based on adsorption of liquid/polymer molecules after infiltration into the porous fibers. These molecules act as dopants that produce large changes in longitudinal fiber resistance, closely related to the low density of carriers near the Fermi level of bulk samples of CNT fibers, reminiscent of their low‐dimensional constituents. A 25% decrease in fiber resistance upon exposure to electron–donor radicals formed during epoxy vinyl ester polymerization is shown as an example. At later stages of curing the matrix undergoes shrinkage and applies a compressive stress to the fibers. The resulting sharp increase in electrical resistance provides a mechanism for detection of the matrix gel point. The kinetics of resistance change during polymer ingress are related to established models for macromolecular adsorption, thus also enabling prediction of polymer flow. This is demonstrated for vacuum infusion of a 150 cm2 glass fiber laminate composite, with the CNT fiber yarns giving accurate prediction of macroscopic resin flow according to Darcy's law. Macroscopic yarns made up of carbon nanotubes (CNTs) are doped by liquids/polymers entering their pores, producing large changes in fiber electrical resistance that follow kinetics of macromolecular adsorption. After calibration, a CNT yarn sensor can detect radical species and the gel point during epoxy curing, and predict polymer flow during fabrication of a 150 cm2 glass fiber laminate composite by vacuum infusion.
      PubDate: 2016-08-22T01:27:09.285611-05:
      DOI: 10.1002/adfm.201602949
       
  • Improving the Property–Function Tuning Range of Thiophene Materials
           via Facile Synthesis of Oligo/Polythiophene‐S‐Oxides and Mixed
           
           
    • Abstract: A platform is described for the first time for the facile synthesis of oligo‐ and polythiophene‐S‐oxides and the corresponding ‐S,S‐dioxides in short times, mild conditions, high yields. Employing ultrasound assistance, brominated thiophenes are selectively mono‐ or dioxygenated at room temperature. These building blocks are then combined with metalated thiophenes via microwave‐assisted cross‐coupling reactions through a “Lego‐like” strategy to afford unprecedented oligo/polythiophene‐S‐oxides and mixed ‐S‐oxides/‐S,S‐dioxides. It is demonstrated that depending on the number, type, and sequence alternation of nonoxygenated, monooxygenated, and dioxygenated thiophene units a very wide property–function tuning can be achieved spanning from frontier orbital energies and energy gaps, to charge transport characteristics and supramolecular H‐bonding interactions with specific proteins inside live cells. A platform is described for ultrasound‐assisted synthesis of oligo‐ and polythiophene‐S‐oxides and ‐S,S‐dioxides in short reaction times, mild conditions, and high yields. By changing the number and sequence alternation of nonoxygenated, monooxygenated, and dioxygenated thiophene units a very wide tuning of frontier orbital energies, charge transport characteristics, and supramolecular H‐bondings to specific intracellular proteins is achieved.
      PubDate: 2016-08-22T01:27:02.18321-05:0
      DOI: 10.1002/adfm.201602996
       
  • Cooperative Effect of GO and Glucose on PEDOT:PSS for High VOC and
           Hysteresis‐Free Solution‐Processed Perovskite Solar Cells
    • Authors: Antonella Giuri; Sofia Masi, Silvia Colella, Alessandro Kovtun, Simone Dell'Elce, Emanuele Treossi, Andrea Liscio, Carola Esposito Corcione, Aurora Rizzo, Andrea Listorti
      Abstract: Hybrid organic–inorganic halide perovskites have emerged at the forefront of solution‐processable photovoltaic devices. Being the perovskite precursor mixture a complex equilibrium of species, it is very difficult to predict/control their interactions with different substrates, thus the final film properties and device performances. Here the wettability of CH3NH3PbI3 (MAPbI3) onto poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer is improved by exploiting the cooperative effect of graphene oxide (GO) and glucose inclusion. The glucose, in addition, triggers the reduction of GO, enhancing the conductivity of the PEDOT:PSS+GO+glucose based nanocomposite. The relevance of this approach toward photovoltaic applications is demonstrated by fabricating a hysteresis‐free MAPbI3 solar cells displaying a ≈37% improvement in power conversion efficiency if compared to a device grown onto pristine PEDOT:PSS. Most importantly, VOC reaches values over 1.05 V that are among the highest ever reported for PEDOT:PSS p‐i‐n device architecture, suggesting minimal recombination losses, high hole‐selectivity, and reduced trap density at the PEDOT:PSS along with optimized MAPbI3 coverage. The synergistic effect of graphene oxide and glucose in improving the conduction properties of polymer electrolyte poly(3,4‐ethyl­enedioxythiophene):poly­(styrenesul­fonate) and modifying the sensible interface of perovskite solar cells is reported. This method allows obtaining hysteresis‐free and high VOC CH3NH3PbI3 devices displaying a ≈37% improvement in power conversion efficiency, evidencing minimal recombination losses and very efficient charge extraction at the electrodes.
      PubDate: 2016-08-22T01:26:40.549176-05:
      DOI: 10.1002/adfm.201603023
       
  • Anode‐Free Rechargeable Lithium Metal Batteries
    • Abstract: Anode‐free rechargeable lithium (Li) batteries (AFLBs) are phenomenal energy storage systems due to their significantly increased energy density and reduced cost relative to Li‐ion batteries, as well as ease of assembly because of the absence of an active (reactive) anode material. However, significant challenges, including Li dendrite growth and low cycling Coulombic efficiency (CE), have prevented their practical implementation. Here, an anode‐free rechargeable lithium battery based on a Cu LiFePO4 cell structure with an extremely high CE (>99.8%) is reported for the first time. This results from the utilization of both an exceptionally stable electrolyte and optimized charge/discharge protocols, which minimize the corrosion of the in situly formed Li metal anode. Anode‐free rechargeable lithium (Li) batteries (AFLBs) are phenomenal energy storage systems due to their significantly increased energy density and reduced cost relative to Li‐ion batteries, as well as ease of assembly because of the absence of an active (reactive) anode material. An extremely high Coulombic efficiency (>99.8%) of the AFLB is demonstrated.
      PubDate: 2016-08-18T01:35:45.388363-05:
      DOI: 10.1002/adfm.201602353
       
  • Naphthacenodithiophene Based Polymers—New Members of the
           Acenodithiophene Family Exhibiting High Mobility and Power Conversion
           Efficiency
    • Abstract: Wide‐bandgap conjugated polymers with a linear naphthacenodithiophene (NDT) donor unit are herein reported along with their performance in both transistor and solar cell devices. The monomer is synthesized starting from 2,6‐dihydroxynaphthalene with a double Fries rearrangement as the key step. By copolymerization with 2,1,3‐benzothiadiazole (BT) via a palladium‐catalyzed Suzuki coupling reaction, NDT‐BT co‐polymers with high molecular weights and narrow polydispersities are afforded. These novel wide‐bandgap polymers are evaluated as the semiconducting polymer in both organic field effect transistor and organic photovoltaic applications. The synthesized polymers reveal an optical bandgap in the range of 1.8 eV with an electron affinity of 3.6 eV which provides sufficient energy offset for electron transfer to PC70BM acceptors. In organic field effect transistors, the synthesized polymers demonstrate high hole mobilities of around 0.4 cm2 V–1 s–1. By using a blend of NDT‐BT with PC70BM as absorber layer in organic bulk heterojunction solar cells, power conversion efficiencies of 7.5% are obtained. This value is among the highest obtained for polymers with a wider bandgap (larger than 1.7 eV), making this polymer also interesting for application in tandem or multijunction solar cells. Naphthacenodithiophene‐benzothiadiazole (NDT‐BT) copolymers have been synthesized via a palladium‐catalyzed Suzuki coupling reaction. Compared to the analogous indacenodithiophene polymers, these NDT‐BT copolymers have a wider bandgap of 1.8 eV. Hole mobilities of around 0.4 cm2 V–1 s–1 are observed and, in combination with a PC70BM acceptor, power conversion efficiencies of 7.5% are obtained in organic bulk heterojunction solar cells.
      PubDate: 2016-08-18T01:35:40.869345-05:
      DOI: 10.1002/adfm.201602285
       
  • Magnetic Field Effect in Organic Light‐Emitting Diodes Based on
           Electron Donor–Acceptor Exciplex Chromophores Doped with Fluorescent
           Emitters
    • Authors: Sangita Baniya; Zhiyong Pang, Dali Sun, Yaxin Zhai, Ohyun Kwon, Hyeonho Choi, Byoungki Choi, Sangyoon Lee, Z. Valy Vardeny
      Abstract: A new type of organic light‐emitting diode (OLED) has emerged that shows enhanced operational stability and large internal quantum efficiency approaching 100%, which is based on thermally activated delayed fluorescence (TADF) compounds doped with fluorescent emitters. Magneto‐electroluminescence (MEL) in such TADF‐based OLEDs and magneto‐photoluminescence (MPL) in thin films based on donor–acceptor (D–A) exciplexes doped with fluorescent emitters with various concentrations are investigated. It has been found that both MEL and MPL responses are thermally activated with substantially lower activation energy compared to that in the pristine undoped D–A exciplex host blend. In addition, both MPL and MEL steeply decrease with the emitter's concentration. This indicates the existence of a loss mechanism, whereby the triplet charge‐transfer state in the exciplex host blend may directly decay to the lowest, nonemissive triplet state of the fluorescent emitter molecules. Using magneto‐electroluminesence in organic light‐emitting diodes of donor–acceptor exciplex compounds doped with fluorescence emitters, we found that the activation energy of the reversed intersystem crossing process is substantially reduced compared with that of the undoped compound. At lower dopant concentration, the rapid Förster energy transfer enhances the electro‐luminesence, whereas at higher dopant concentration Dexter energy transfer interferes, creating a loss mechanism.
      PubDate: 2016-08-18T01:35:30.458418-05:
      DOI: 10.1002/adfm.201601669
       
  • Cold Sintering Process of Composites: Bridging the Processing Temperature
           Gap of Ceramic and Polymer Materials
    • Authors: Jing Guo; Seth S. Berbano, Hanzheng Guo, Amanda L. Baker, Michael T. Lanagan, Clive A. Randall
      Abstract: Co‐sintering ceramic and thermoplastic polymer composites in a single step with very high volume fractions of ceramics seems unlikely, given the vast differences in the typical sintering temperatures of ceramics versus polymers. These processing limitations are overcome with the introduction of a new sintering approach, namely “cold sintering process” (CSP). CSP utilizes a transient low temperature solvent, such as water or water with dissolved solutes in stoichiometric ratios consistent with the ceramic composition, to control the dissolution and precipitation of ceramics and effect densification between room temperature and ≈200 °C. Under these conditions, thermoplastic polymers and ceramic materials can be jointly formed into dense composites. Three diphasic composite examples are demonstrated to show the overall diversity of composite material design between organic and inorganic oxides, including the microwave dielectric Li2MoO4–(C2F4 ) n , electrolyte Li1.5Al0.5Ge1.5(PO4)3–(CH2CF2 ) x [CF2CF(CF3)] y , and semiconductor V2O5–poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate composites. Cold sintering is more general and shall have a major impact on the processing of composite materials for many different applications, mechanical, thermal, and electronic, to mention a few possibilities. CSP concepts open up new composite material design and device integration schemes, impacting a wide variety of applications. “Cold Sintering Process” (CSP) is an extremely low temperature sintering process (between room temperature and ≈200 °C), which makes it promising to co‐sinter ceramic and thermoplastic polymer composites in a simple one‐step sintering processing. CSP concepts open up new composite material design with many different applications, such as electrical and mechanical.
      PubDate: 2016-08-18T01:31:39.897094-05:
      DOI: 10.1002/adfm.201602489
       
  • DNA‐Responsive Polyisocyanopeptide Hydrogels with
           Stress‐Stiffening Capacity
    • Authors: Swapneel R. Deshpande; Roel Hammink, Rajat K. Das, Frank H. T. Nelissen, Kerstin G. Blank, Alan E. Rowan, Hans A. Heus
      Abstract: Biological materials have evolved to combine a number of functionally relevant properties. They are sensitive to chemical and mechanical signals and respond to these signals in a highly specific manner. Many biological hydrogels possess the ability to stress‐stiffen, a property that is difficult to mimic in synthetic systems. A novel synthetic hydrogel is described that possesses stress‐stiffening behavior in the biologically relevant stress regime and, at the same time, contains DNA cross‐links as stimuli‐responsive elements. The hydrogel scaffold is composed of oligo(ethylene glycol)‐functionalized polyisocyanopeptides (PIC), which show a sol‐to‐gel transition upon increasing the temperature. It is shown that the mechanical properties of the hybrid hydrogel depend on DNA cross‐linker concentration and temperature. At high temperature, a hydrophobically bundled stress‐stiffening PIC network forms. By contrast, gel formation is controlled by DNA cross‐linking at temperatures below the PIC sol‐to‐gel transition. The DNA cross‐linked hydrogel also exhibits stress‐stiffening behavior and its properties are controlled by the DNA cross‐linker concentration. The hydrogel properties can further be tuned when using DNA cross‐linkers with different melting temperature or when breaking cross‐links by strand displacement. This clearly shows the potential of DNA cross‐links as stimuli‐responsive elements, highlighting the possible applications of this hybrid hydrogel as a new sensor. A DNA‐responsive hydrogel system is presented that mimics stress‐stiffening behavior and mechanical properties of biological hydrogels. The mechanical properties of the network can be controlled by DNA cross‐linker concentration and temperature and are reversible using a toehold strategy. This combination of thermoresponsive polymers and controllable responsive DNA elements offers a new soft material platform with great versatility and applicability.
      PubDate: 2016-08-18T01:25:31.391651-05:
      DOI: 10.1002/adfm.201602461
       
  • Real‐Time Imaging of Cell Behaviors in Living Organisms by a
           Mitochondria‐Targeting AIE Fluorogen
    • Authors: Bo Situ; Sijie Chen, Engui Zhao, Chris Wai Tung Leung, Yilong Chen, Yuning Hong, Jacky Wing Yip Lam, Zilong Wen, Wei Liu, Wenqing Zhang, Lei Zheng, Ben Zhong Tang
      Abstract: Visualizing behaviors of cell populations within living multicellular organisms in real time is of great value to life science but challenging due to the lack of ideal probes. In this work, a biocompatible fluorogen, azide‐functionalized tetraphenylethene pyridinium (TPE‐PyN3), is reported for noninvasive imaging and sensing within living systems. TPE‐PyN3 exhibits unique aggregation‐induced emission (AIE) attributes and high affinity to mitochondria, enabling it to achieve specific mitochondrial imaging and long‐term cellular observing with excellent photostability both in vitro and in vivo. The high membrane penetrability of TPE‐PyN3 allows all of the cells within the living zebrafish embryos to be morphologically visualized and reconstructed in 3D. Moreover, TPE‐PyN3 is capable of indicating cell apoptosis because of its sensitivity to the change of mitochondrial membrane potential. The findings presented here provide a simple and noninvasive tool for studying behaviors of cell populations in vivo for the first time by a small‐molecule AIE probe. An aggregation‐induced emission active probe with distinctive properties for biological imaging and sensing in cultured cells and in living systems is presented. Novel applications of this probe such as in situ cellular imaging and cell apoptosis detection in living zebrafish embyros are demonstrated.
      PubDate: 2016-08-17T06:26:24.436866-05:
      DOI: 10.1002/adfm.201602865
       
  • Performance Limits of the Self‐Aligned Nanowire Top‐Gated MoS2
           Transistors
    • Authors: Zhenyu Yang; Xingqiang Liu, Xuming Zou, Jingli Wang, Chao Ma, Changzhong Jiang, Johnny C. Ho, Caofeng Pan, Xiangheng Xiao, Jie Xiong, Lei Liao
      Abstract: In order to realize the promising potential of MoS2 as the alternative channel material, it is essential to achieve high‐performance top‐gated MoS2 field‐effect transistors (FETs), especially since the back‐gated counterparts cannot control the device individually. Although uniform high‐k dielectric films, such as HfO2, can be obtained through the introduction of artificial nucleation sites on the MoS2 channel to fabricate top‐gated FETs, this would inevitably degrade their channel/dielectric interface quality, induce significant charged impurity scattering and lower carrier mobility. In this work, MoS2 FETs are fabricated using a self‐aligned nanowire top‐gate, which can effectively reduce the charged impurity scattering on the surface of MoS2. Specifically, the fabricated short‐channel devices exhibit impressive electrical performances, such as the high on/off current ratio, low interface trap density, and near‐ideal subthreshold slope at room temperature. In addition, the short channel effect is systematically analyzed, which indicates that the phonon scattering can be the dominant scattering mechanism in the devices when the amount of charged impurities is effectively reduced with the self‐aligned nanowire gate. All these provide an enhanced fabrication scheme to attain top‐gated short‐channel devices with the optimized interface and potentially to explore their corresponding performance limits. MoS2 field effect transistors using a self‐aligned nanowire top‐gate exhibit a reduced charged impurity scattering in their channel/gate interface. Considering their short channel lengths, all devices exhibit an impressive electrical performance at room temperature. In addition, the performance degradation resulting from the short channel effects is systematically analyzed.
      PubDate: 2016-08-17T06:25:56.336246-05:
      DOI: 10.1002/adfm.201602250
       
  • Elevating Biomedical Performance of ZnO/SiO2@Amorphous Calcium Phosphate
           ‐ Bioinspiration Making Possible the Impossible
    • Abstract: Here a biomimetic approach is presented to fabricate nanodragon fruits featured by a multitude of tiny quantum dot ZnO seeds embedded in mesosilica (SiO2) flesh then enclosed in amorphous calcium phosphate (ACP) shell. The nanodragon fruits give rise to a new class of hybrid ZnO/SiO2@ACP nanocomplex with multimoidal capability: cellular delivering, intracellular targeting, and subcellular imaging. With this particular design, the unusual fluorescent stability of ZnO quantum dots (QDs) in aqueous solution, the specific color selection of the functional ZnO QD seeds, and the stability of transient ACP over a long period of time are made possible. In addition, the nanodragon fruits, capable of targeting mitochondria, have elevated biocompatibility, thus can be of enormous potential applications in treating mitochondrial diseases including inflammation, neurodegeneration, obesity, diabetes, cardiovascular diseases, and cancer. As numerous human disorders are often associated with cellular dysfunctions, this biocompatible carrying platform, capable of delivering, targeting, and imaging subcellular organelles, is therefore highly desirable for efficacious therapeutic and diagnostic treatment. Nucleation and its controlling factors, e.g., supersaturation, pH, solvents, and additives are applied in designing and engineering the seed‐flesh‐shell structure of ZnO–SiO2–amorphous calcium phosphate, namely, ZnO/SiO2@ACP nanodragon fruits with stable fluorescent properties in aqueous solution, precise color selection, and multimoidal capability: cellular delivering, intracellular targeting, and subcellular imaging.
      PubDate: 2016-08-17T06:20:34.713383-05:
      DOI: 10.1002/adfm.201601481
       
  • Electric‐Field‐Controlled Alignment of Rod‐Shaped
           Fluorescent Nanocrystals in Smectic Liquid Crystal Defect Arrays
    • Authors: Iryna Gryn; Emmanuelle Lacaze, Luigi Carbone, Michele Giocondo, Bruno Zappone
      Abstract: Periodic micro‐arrays of straight linear defects containing nanoparticles can be created over large surface areas at the transition from the nematic to smectic‐A phase in a nanoparticle–liquid crystal (LC) composite material confined under the effect of conflicting anchoring conditions (unidirectional planar vs normal) and electric fields. Anisomeric dichroic dye molecules and rod‐shaped fluorescent semiconductor nanocrystals (dot‐in‐rods) with large permanent electric dipole and high linearly polarized photoluminescence quantum yield align parallel to the local LC molecular director and follow its reorientation under application of the electric field. In the nano‐sized core regions of linear defects, where the director is undefined, anisotropic particles align parallel to the defect whereas spherical quantum dots do not show any particular interaction with the defect. Under application of an electric field, ferroelectric semiconductor nanoparticles in the core region align along the field, perpendicular to the defect direction, whereas dichroic dyes remain parallel to the defect. This study provides useful insights into the complex interaction of anisotropic nanoparticles and anisotropic soft materials such as LCs in the presence of external fields, which may help the development of field‐responsive nanoparticle‐based functional materials. Alignment of rod‐shaped semiconductor nanocrystals can be achieved via interaction with a smectic‐A liquid crystal that self‐assembles into micro‐arrays containing linear topological defects and responds to applied electric fields. Nanoparticles align parallel to the molecular director and follow its response to the field, but align parallel to the defects or along the field inside the nanosized defect cores.
      PubDate: 2016-08-16T08:56:03.393655-05:
      DOI: 10.1002/adfm.201602729
       
  • High‐Temperature BiScO3‐PbTiO3 Piezoelectric Vibration Energy
           Harvester
    • Authors: Jingen Wu; Huaduo Shi, Tianlong Zhao, Yang Yu, Shuxiang Dong
      Abstract: Conventionally, effective mechanical vibration energy harvesting is based on (Pb,Zr)TiO3 (PZT) ceramics, poly(vinylidene fluoride) (PVDF) polymers or PVDF/PZT or other piezoelectric composite materials, and their working temperature is normally limited to room temperature (R‐T) or below 150 °C. Here, bismuth scandium lead titanate (BiScO3‐PbTiO3, abbreviated as BSPT) ceramic is reported which has a high Curie temperature point around 450 °C and its application for high‐temperature (H‐T) vibration energy harvesting. Experimental results show that it exhibits an excellent H‐T piezoelectricity, converting mechanical vibration energy into electric power effectively in a wide temperature range from R‐T till 250 °C. This research shows the BSPT piezoelectric energy harvester having the potential application for self‐power source of wireless sensor network system in high temperature circumstance. Conventionally, effective mechanical vibration energy harvesting is based on (Pb,Zr)TiO3 (PZT) ceramics, polyvinylidene fluoride (PVDF) polymers or PVDF/PZT, and/or other piezoelectric composite materials, and their working temperature is normally limited to room temperature (R‐T) or below 150 °C. Here, a high‐temperature BiScO3‐PbTiO3 piezoelectric vibration energy harvester is reported, which works effectively in a wide temperature range from R‐T till 250 °C.
      PubDate: 2016-08-16T08:55:56.437763-05:
      DOI: 10.1002/adfm.201602645
       
  • Photoreduced Graphene Oxide as a Conductive Binder to Improve the Water
           Splitting Activity of Photocatalyst Sheets
    • Authors: Zhenhua Pan; Takashi Hisatomi, Qian Wang, Shanshan Chen, Akihide Iwase, Mamiko Nakabayashi, Naoya Shibata, Tsuyoshi Takata, Masao Katayama, Tsutomu Minegishi, Akihiko Kudo, Kazunari Domen
      Abstract: Photocatalyst sheets consisting of H2 evolution photocatalyst (HEP) and O2 evolution photocatalyst (OEP) particles applied to an underlying conductive layer show promise with regard to promoting efficient and scalable water splitting. One of the most important challenges in enhancing the performance of such systems is establishing efficient charge transfer between photocatalyst particles that are often thickly stacked on the conductive layer. In this study, reduced graphene oxide (RGO) is investigated as an additional solid mediator to the conductive layer to bridge particulate photocatalysts and thus ensure effective charge transfer. Photocatalyst sheets made of RhCrOx/LaMg1/3Ta2/3O2N as the HEP and BiVO4:Mo as the OEP are applied to an Au layer together with RGO. The activity of this system is 3.5 times greater following the incorporation of the RGO. Charaterization analyses reveal that RhCrOx/LaMg1/3Ta2/3O2N particles tens of nanometers in size are fixed on larger, micrometer‐sized, BiVO4:Mo particles by RGO photoreduced from GO in situ. The RGO facilitates charge transfer between particles that are distant from the underlying Au layer and thus involves more photocatalyst particles in the water splitting reaction. It is concluded that the incorporation of conductive materials into the photocatalyst particle layer can effectively enhance the water splitting activity of photocatalyst sheets. Reduced graphene oxide incorporated into the photocatalyst sheet, composed of RhCrOx/LaMg1/3Ta2/3O2N as a hydrogen evolution photocatalyst and BiVO4:Mo as an oxygen evolution photocatalyst embeded in an Au layer, effectively facilitates charge transfer between particles that are distant from the underlying Au layer and enhances the activity for Z‐scheme water splitting by 3.5 times.
      PubDate: 2016-08-16T08:55:51.563188-05:
      DOI: 10.1002/adfm.201602657
       
  • Reducible‐Shell‐Derived Pure‐Copper‐Nanowire
           Network and Its Application to Transparent Conducting Electrodes
    • Abstract: The concept of using core Cu nanowires (CuNWs) that are conformally encapsulated by a reducible fugitive material for transparent conducting electrodes (TCEs) with high oxidation stability is presented. By the chemical reaction of an acid with surface oxide and hydroxide, a uniform surface shell layer is readily obtained on each CuNW upon adding lactic acid to the CuNW dispersion. The Cu lactate shell prevents the core CuNW from oxidizing during storage and film formation, enabling the core Cu nanowires to maintain their characteristic optoelectronic properties. Through simple thermal annealing under a nitrogen atmosphere, the Cu lactate shell is easily decomposed to expose the underlying pure Cu, providing an effective way to produce a pure‐CuNW‐network TCE with a sheet resistance of 19.8 Ω sq−1 and an optical transmittance of 85.5% at 550 nm. The application of the CuNW‐based TCE to the transparent top electrode in organometallic halide perovskite solar cells is further demonstrated for the first time, yielding a power‐conversion efficiency 9.88% as compared to that of 13.39% for conventional perovskite solar cells with an indium–tin‐oxide electrode. This study proposes the high feasibility of these CuNWs as a vacuum‐free and noble‐metal‐free transparent‐window electrode in perovskite solar cells. Copper–copper‐lactate core–shell nanowires (NWs) are introduced via simple one‐pot synthesis. Thermally reducible Cu‐lactate shells conformally encapsulate individual CuNWs, providing long‐term oxidation stability. Cu–Cu‐lactate core–shell NW is transformed into highly conductive CuNW‐based transparent electrodes without a reductive atmosphere.
      PubDate: 2016-08-16T08:55:45.857243-05:
      DOI: 10.1002/adfm.201602094
       
  • Scissor‐Like Chiral Metamolecules for Probing Intracellular
           Telomerase Activity
    • Authors: Maozhong Sun; Liguang Xu, Pan Fu, Xiaoling Wu, Hua Kuang, Liqiang Liu, Chuanlai Xu
      Abstract: A DNA‐driven gold (Au) heterodimer for intracellular telomerase detection is fabricated. The highly biocompatible and intracellularly stable probe shows an active chiroptical property in the visible region, due to the scissor‐like configuration formed by prolate nanoparticles. Importantly, the telomerase activity is specifically quantified using circular dichroism intensity in situ after internalization of the heterodimer into cancer cells. Moreover, the results clearly illustrate that this method has a remarkable linear range from 0.8 × 10−12 to 32 × 10−12 IU, and the limit of detection for telomerase activity is 1.7 × 10−15 IU in a single HeLa cell. This strategy paves the way for chirality‐based ultrasensitive detection of intracellular cancer markers. In this work, DNA‐driven scissor‐like chiral metamolecules for intracellular telomerase detection are fabricated. The telomerase activity is specifically quantified using circular dichroism intensity in situ. The results show that this method has a remarkable linear range from 0.8 × 10−12 to 32 × 10−12 IU, and the limit of detection for telomerase activity is 1.7 × 10−15 IU in a single HeLa cell.
      PubDate: 2016-08-16T08:55:38.139598-05:
      DOI: 10.1002/adfm.201601942
       
  • Hierarchical Graphene‐Based Films with Dynamic Self‐Stiffening
           for Biomimetic Artificial Muscle
    • Authors: Zhaohe Dai; Yanlei Wang, Luqi Liu, Xuelu Liu, PingHeng Tan, Zhiping Xu, Jun Kuang, Qing Liu, Jun Lou, Zhong Zhang
      Abstract: Biological tissues such as muscle cells can adapt their structural and mechanical response upon external mechanical stimuli. Conversely, artificial muscles, intended to reproduce the salient functional features of biological muscles, usually undergo mechanical fatigue when subjected to dynamic stress. Besides passively improving the resilience to dynamic loads, here, it is reported that macroscopic films based on graphene and its chemical derivate exhibit an increase in modulus by up to 84% after subjected to a low‐amplitude (0.1%) dynamic tension. Through a combination of experimental testing and molecular dynamics simulations, the unique self‐stiffening behavior is attributed to the straightening and reorientation of graphene sheets and is further tuned through tailoring interlayer adhesion. Meanwhile, artificial muscles based on graphene films are designed and interestingly improved stiffness of our muscle materials after “training” are demonstrated. These results help to harness the stiffening mechanism and can be useful for the development of adaptable structural materials for biomechanical applications. Macroscopic films based on hierarchical graphene and its chemical derivate possessing tunable interfacial features are synthesized. This paper describes the self‐stiffening responses of these macroscopic materials to dynamic tension and demonstrates an as high as 84% increase in Young's modulus. Systematic mechanical tests, microstructural characterizations, molecular dynamics simulations, and model analysis are performed to clarify the unusual self‐stiffening mechanism. By utilizing these graphene‐based films, artificial muscles with dynamic self‐stiffening behavior are designed.
      PubDate: 2016-08-16T08:55:32.434672-05:
      DOI: 10.1002/adfm.201503917
       
  • Design Strategy of Blue and Yellow Thermally Activated Delayed
           Fluorescence Emitters and Their All‐Fluorescence White OLEDs with
           External Quantum Efficiency beyond 20%
    • Abstract: Two thioxanthone‐derived isomeric series of thermally activated delayed fluorescence (TADF) emitters 1,6‐2TPA‐TX/3,6‐2TPA‐TX and 1,6‐2TPA‐TXO/3,6‐2TPA‐TXO are developed for organic light‐emitting diodes (OLEDs). Blue emission devices based on symmetrical 3,6‐2TPA‐TX with common vertical transition route realize an extremely high external quantum efficiency (EQE) of 23.7%, and an ever highest EQE of 24.3% is achieved for yellow emission devices based on 3,6‐2TPA‐TXO by solely changing the sulfur atom valence state of the thioxanthone core. In contrast, their corresponding asymmetric isomers are affected by intramolecular energy transfer and more severely by a nonradiative deactivation pathway, to give much low EQE values (
      PubDate: 2016-08-16T08:55:25.542233-05:
      DOI: 10.1002/adfm.201602507
       
  • Composition and Structure of Oyster Adhesive Reveals Heterogeneous
           Materials Properties in a Biological Composite
    • Authors: Rebecca A. Metzler; Rebecca Rist, Erik Alberts, Paul Kenny, Jonathan J. Wilker
      Abstract: Oyster reefs help maintain coastal ecosystems by filtering water, holding silt in place, and absorbing storm surge energy. We are just beginning to understand the chemical and structural nature of the adhesive used by these animals for building such reef communities. The adhesive has a high calcium carbonate content relative to other bioadhesives, but also appreciable levels of organics, presumably for bonding. The studies presented here use X‐ray absorption near edge structure spectroscopy, X‐ray photoemission electron microscopy, scanning electron microscopy, and microhardness methods to understand the composition, as well as the mechanical properties, of this biological material. Oyster adhesive appears to be a heterogeneous mixture of calcium carbonate and silica inclusions arranged randomly within a matrix that lacks any observable structure. Microindentation shows inclusions are significantly harder than their surroundings. This hard plus soft strategy has been noted in other biological materials, although not in any adhesives. These compositional and structural insights help propose a mechanism by which the animals generate their adhesive. Such an intriguing structure, along with resulting mechanical implications, may help explain how oyster reefs can thrive despite being subjected to demanding forces created by predators and the environment around them. X‐ray photoemission electron microscopy polarization dependent imaging contrast and microindentation of the Crassostrea virginica adhesive–shell boundary show the adhesive is an unstructured composite consisting of hard inclusions within a soft matrix. The shells on either side have multicrystalline calcite prisms of varied structure and significantly greater hardness than the average adhesive.
      PubDate: 2016-08-16T08:30:54.907946-05:
      DOI: 10.1002/adfm.201602348
       
  • Engineering the Mechanics of Heterogeneous Soft Crystals
    • Abstract: This work demonstrates how the geometric and topological characteristics of substructures within heterogeneous materials can be employed to tailor the mechanical responses of soft crystals under large strains. The large deformation mechanical behaviors of elastomeric composites possessing long‐range crystalline order are examined using both experiments on 3D‐printed prototype materials and precisely matched numerical simulations. The deformation mechanisms at small and large strains are elucidated for six sets of morphologies: dispersed particles on each of the simple cubic, body‐centered cubic or face‐centered cubic lattices, and their bi‐continuous counterparts. Comparison of results for the six types of morphologies reveals that the topological connectivity of dissimilar domains is of critical importance for tailoring the macroscopic mechanical properties and the mechanical anisotropy. Tailoring the mechanical responses of soft crystals under large strains by employing the geometric characteristics is demonstrated. The large deformation mechanical behaviors of elastomeric composites possessing long‐range crystalline order are examined using both experiments and numerical simulations. The results revealed that the topological connectivity of dissimilar domains is of critical importance for tailoring the macroscopic mechanical properties and the mechanical anisotropy.
      PubDate: 2016-08-12T06:09:00.804588-05:
      DOI: 10.1002/adfm.201601719
       
  • From White to Red: Electric‐Field Dependent Chromaticity of
           
    • Abstract: The differences in the electroluminescence (EL) of red‐emitting free‐base (H2TPP) and Zn‐metalated (ZnTPP) archetypal porphyrins are rationalized in light‐emitting electrochemical cells by means of an electric‐field dependent effect, leading to whitish and reddish devices, respectively. Although H2TPP shows superior electrochemical and photophysical features compared to ZnTPP, devices prepared with ZnTPP surprisingly stand out with a deep‐red EL similar to its photoluminescence (PL), while H2TPP devices feature unexpected whitish EL. Standard arguments such as degradation, device architecture, device mechanism, and changes in the nature of the emitting excited states are discarded. Based on electrochemical impedance spectroscopy and first‐principles electronic structure methods, we provide evidence that the EL originates from two H2TPP regioisomers, in which the inner ring H atoms are placed in collinear and vicinal configurations. The combination of their optical features provides an explanation for both the high‐ and low‐energy EL features. Here, the emitting excited state nature is ascribed to the Q bands, since the Soret excited states remain high in energy. This contrasts to what is traditionally postulated in reports focused on H2TPP lighting devices. Hence, this work provides a new explanation for the nature of the high‐energy EL band of H2TPP that might inspire future works focused on white‐emitting molecular‐based devices. White‐emitting porphyrin devices. Although H2TPP is better suited for deep‐red emitting thin‐film devices compared to ZnTPP, yellowish‐white electroluminescence response is noted for H2TPP devices. This unexpected result is related to the presence of two emitting regioisomers of H2TPP induced by the externally applied electric field.
      PubDate: 2016-08-11T06:15:46.016171-05:
      DOI: 10.1002/adfm.201602252
       
  • One‐Step Synthesis of CoS‐Doped β‐Co(OH)2@Amorphous
           MoS2+ x Hybrid Catalyst Grown on Nickel Foam for High‐Performance
           Electrochemical Overall Water Splitting
    • Authors: Taeseung Yoon; Kwang S. Kim
      Abstract: Developing efficient and economical electrocatalysts for hydrogen evolution reaction and oxygen evolution reaction with readily available metals is one of the main challenges for large scale hydrogen/oxygen production. This study reports one step synthesis of cobalt and molybdenum hybrid materials for high performance overall water splitting. The binder‐free CoS‐doped β‐Co(OH)2@amorphous MoS2+x is coated on nickel foam (NF) to form 3D networked nanoplates that have large surface area and high durability for electrochemical reactions. The catalytic activity of electrocatalyst for hydrogen evolution is mainly attributed to the unsaturated sulfur site of amorphous MoS2+x. Meanwhile, the CoS‐doped β‐Co(OH)2 plays the major role in oxygen evolution. CoS‐doped β‐Co(OH)2 and aMoS2+x are strongly bound to each other due to CoSx bridging. This CoSCo(OH)2@aMoS2+x/NF hybrid exhibits excellent catalytic activity and stability for overall water splitting. For over 100 000 s the cell voltage required to achieve the current density of 10 mA cm–2 is only 1.58 V, which is remarkably low among the commercially available electrocatalysts. The findings open up an easy and inexpensive method of large scale fabrication of bifunctional electrocatalysts for overall water splitting. Bifunctional CoS–Doped β–Co(OH)2@amorphous MoS2+x grown on nickel foam is fabricated using one‐step synthesis. This material provides excellent electrocatalytic activity and high stability, requiring a cell voltage of only 1.58 V to achieve 10 mA cm−2 current density in alkaline media when used as overall water splitting electrode.
      PubDate: 2016-08-11T06:15:29.531204-05:
      DOI: 10.1002/adfm.201602236
       
  • Aggregation Induced Enhancement of Linear and Nonlinear Optical Emission
           from a Hexaphenylene Derivative
    • Abstract: The discovery of the phenomenon known as aggregation‐induced emission (AIE) has opened the door to a variety of brilliant organic solid‐state light‐emitting materials. While AIE is well established in linear optics, the development of AIE luminogens (AIEgens) with highly efficient nonlinear optical (NLO) effects remains relatively unexplored. Particularly, second‐order NLO requires the AIEgens to be organized in a non‐centrosymmetric fashion, and such examples are rarely reported. Here, an AIEgen, 2,7‐di([1,1′‐biphenyl]‐4‐yl)‐fluorenone (4‐DBpFO), is designed and synthesized by introducing a carbonyl group onto the backbone of p‐hexaphenylene. The restricted rotation of the compound upon aggregation results in a dramatic enhancement of the linear optical emission when forming self‐assemblies. Furthermore, introducing the carbonyl group drives the formation of hydrogen bonded molecular chains, which are attached by the zigzag CH⋅⋅⋅π interactions in a non‐centrosymmetric way. As a result, the dipole of each individual molecule contributes accumulatively to a macroscopic dipole of the formed 4‐DBpFO microcrystals. This leads to a highly efficient second harmonic generation with very high laser damage treshold. This AIEgen, whose optical response is greatly enhanced in both linear and nonlinear optical regimes upon the formation of well‐defined self‐assemblies, has potential applications in next generation photonic circuits. An aggregation‐induced emission luminogen active in both linear and nonlinear optics is designed and synthesized based on the p‐hexaphenylene backbone. The self‐assembled microstructures demonstrate a linear optical quantum efficiency of about ten times higher than that of the solution state, and a highly efficient and stable second harmonic generation signal greater than that of lithium niobate.
      PubDate: 2016-08-08T10:31:45.089351-05:
      DOI: 10.1002/adfm.201602765
       
  • Aerophilic Electrode with Cone Shape for Continuous Generation and
           Efficient Collection of H2 Bubbles
    • Authors: Cunming Yu; Moyuan Cao, Zhichao Dong, Kan Li, Cunlong Yu, Jingming Wang, Lei Jiang
      Abstract: Hydrogen as a sustainable and clean energy source has attracted great attention with the increasing global energy crisis. However, sufficient production of hydrogen is seriously impeded by the adhesion of hydrogen bubble to electrodes. Efficient removal of hydrogen bubbles attached to the electrode can improve the efficiency of the hydrogen evolution reaction. Following this concept, numerous approaches to shorten the adhesion time of hydrogen bubbles on electrodes have been presented, such as ultrasonic treatment and electrode surface micro/nano‐modification. Almost all of the existing solutions are based on the instant and direct release of generated hydrogen bubbles into the electrolyte, which can be identified as “Releasing strategy” accordingly. In this contribution, an aerophilic electrode with cone shape is fabricated, from which the generated hydrogen bubbles can be timely removed through efficient and directional transportation (from tip to the base). Correspondingly, this approach is defined as “Transporting strategy”. Furthermore, integrating the base of electrode with a superaerophilic sponge, which possesses excellent properties of efficiently absorbing and releasing gas bubbles, can realize the collection of generated hydrogen. It is believed that the present approach can contribute to promising applications in water electrolysis and will offer inspiration for fabricating novel hydrogen collector. Hydrogen bubble adhesion on electrodes greatly impedes the widespread practical application of the hydrogen evolution reaction. In this work, a novel “transporting strategy” for efficiently removing the adhered hydrogen bubbles from the electrode is proposed. The transport is enabled by the conical morphology and aerophilic wettability of the electrode.
      PubDate: 2016-08-08T10:31:28.969521-05:
      DOI: 10.1002/adfm.201601960
       
  • On the Origin of Hysteresis in Perovskite Solar Cells
    • Abstract: The origin of hysteresis behavior is probed in perovskite solar cells (PSCs) with simultaneous measurements of cell open circuit voltage (Voc) and photoluminescence intensity over time following illumination of the cell. It is shown, for the first time, that the transient changes in terminal voltage and luminescent intensity do not follow the relationship that would be predicted by the generalized Plank radiation law. A mechanism is proposed based on the presence of a resistive barrier to majority carrier flow at the interface between the perovskite film and the electron or hole transport layer, in combination with significant interface recombination. This results in a decoupling of the internal quasi‐Fermi level separation and the externally measured voltage. A simple numerical model is used to provide in‐principle validation for the proposed mechanism and it is confirmed that mobile ionic species are a likely candidate for creating the time‐varying majority carrier bottleneck by its reduced conductivity. The findings show that the Voc of PSCs may be lower than the limit imposed by the cell luminescence efficiency, even under steady‐state conditions. The origin of hysteresis behavior in perovskite solar cells is probed with simultaneous measurements of cell open circuit voltage and photoluminescence intensity over time following illumination of the cell. The findings demonstrate the existence of a resistive barrier to majority carrier flow at the interfaces of these devices, in combination with significant interface recombination.
      PubDate: 2016-08-08T10:28:29.270822-05:
      DOI: 10.1002/adfm.201602231
       
  • Understanding of the Extremely Low Thermal Conductivity in
           High‐Performance Polycrystalline SnSe through Potassium Doping
    • Abstract: P‐type polycrystalline SnSe and K0.01Sn0.99Se are prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). The highest ZT of ≈0.65 is obtained at 773 K for undoped SnSe by optimizing the MA time. To enhance the electrical transport properties of SnSe, K is selected as an effective dopant. It is found that the maximal power factor can be enhanced significantly from ≈280 μW m−1 K−2 for undoped SnSe to ≈350 μW m−1 K−2 for K‐doped SnSe. It is also observed that the thermal conductivity of polycrystalline SnSe can be enhanced if the SnSe powders are slightly oxidized. Surprisingly, after K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nanoprecipitates in the SnSe matrix contribute to an impressively low lattice thermal conductivity of ≈0.20 W m−1 K−1 at 773 K along the sample section perpendicular to pressing direction of SPS. This extremely low lattice thermal conductivity coupled with the enhanced power factor results in a record high ZT of ≈1.1 at 773 K along this direction in polycrystalline SnSe. The thermal conductivity significantly decreases after K doping in polycrystalline SnSe. The absence of Sn oxides at the grain boundaries and presence of coherent nanoprecipitates in SnSe matrix result in an impressively low lattice thermal conductivity. Coupled with enhanced power factor results in a maximum figure of merit (ZT) ≈ 1.1 at 773 K, which is the highest value ever reported in polycrystalline SnSe.
      PubDate: 2016-08-08T10:02:31.517976-05:
      DOI: 10.1002/adfm.201602652
       
  • Covalent Bond Scission in the Mullins Effect of a Filled Elastomer:
           Real‐Time Visualization with Mechanoluminescence
    • Authors: Jess M. Clough; Costantino Creton, Stephen L. Craig, Rint P. Sijbesma
      Abstract: Strain‐induced light emission from mechanoluminescent cross‐linkers in silica‐filled poly(dimethylsiloxane) demonstrates that covalent bond scission contributes significantly to irreversible stress‐softening upon the initial extension, known as the Mullins effect. The cross‐linkers contain dioxetanes that emit light upon force‐induced bond scission. The filled elastomer emits light in cyclic uniaxial tension, but only on exceeding the previous maximum strain. The amount of light increases with hysteresis energy in a power law of exponent 2.0, demonstrating that covalent bond scission becomes increasingly important in the strain regime studied. Below 100%–120% strain, corresponding to energy absorption of (0.082 ± 0.012) J cm−3, mechanoluminescence is not detectable. Calibration of the light intensity indicates that by 190% strain, less than 0.1% of the dioxetane moieties break. Small but significant amounts of light are emitted upon unloading, suggesting a complex stress transfer to the dioxetanes mediated by the fillers. Pre‐strained material emits light on straining perpendicularly, but not parallel to the original tensile direction, demonstrating that covalent bond scission is highly anisotropic. These findings show that the scission of even a small number of covalent bonds plays a discernible role in the Mullins effect in filled silicone elastomers. Such mechanisms may be active in other types of filled elastomers. Applying cycles of tensile strain to silica‐filled poly(dimethylsiloxane) functionalized with 1,2‐dioxetanes leads to the emission of mechanically induced chemiluminescence as covalent bonds break in the material. Monitoring in real time, light emission is observed predominantly on the first cycle to a strain. Covalent bond scission is shown conclusively to contribute to Mullins stress‐softening and to exhibit strong anisotropy.
      PubDate: 2016-08-05T06:28:23.436496-05:
      DOI: 10.1002/adfm.201602490
       
  • In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p–n
           Homojunctions for Enhanced Photocatalytic Hydrogen Production
    • Authors: Guigao Liu; Guixia Zhao, Wei Zhou, Yanyu Liu, Hong Pang, Huabin Zhang, Dong Hao, Xianguang Meng, Peng Li, Tetsuya Kako, Jinhua Ye
      Abstract: Graphitic carbon nitride (g‐C3N4) has recently emerged as an attractive photocatalyst for solar energy conversion. However, the photocatalytic activities of g‐C3N4 remain moderate because of the insufficient solar‐light absorption and the fast electron–hole recombination. Here, defect‐modified g‐C3N4 (DCN) photocatalysts, which are easily prepared under mild conditions and show much extended light absorption with band gaps decreased from 2.75 to 2.00 eV, are reported. More importantly, cyano terminal CN groups, acting as electron acceptors, are introduced into the DCN sheet edge, which endows the DCN with both n‐ and p‐type conductivities, consequently giving rise to the generation of p–n homojunctions. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation, and results in a fivefold enhanced photocatalytic H2 evolution activity. The findings deepen the understanding on the defect‐related issues of g‐C3N4‐based materials. Additionally, the ability to build homojunction structures by the defect‐induced self‐functionalization presents a promising strategy to realize precise band engineering of g‐C3N4 and related polymer semiconductors for more efficient solar energy conversion applications. The p–n homojunction graphitic carbon nitride (g‐C3N4) photocatalysts with extended light absorption are prepared via in situ bond modulation, which is achieved by low‐temperature heating g‐C3N4 with NaBH4. Such a p–n homojunction endows g‐C3N4 with much increased π‐electron delocalization and highly improved carrier separation and transfer. Consequently, the materials exhibit a fivefold enhanced photocatalytic hydrogen evolution activity under visible light irradiation.
      PubDate: 2016-08-05T06:28:11.020973-05:
      DOI: 10.1002/adfm.201602779
       
  • Material‐Driven Fibronectin Assembly Promotes Maintenance of
           Mesenchymal Stem Cell Phenotypes
    • Abstract: Mesenchymal stem cells (MSCs) are a research tool to investigate fundamental biology and are candidates for use in regenerative medicine. In this context, significant efforts have been devoted to develop technologies to control stem cell fate, including the use of soluble factors in media. However, material properties offer alternative approaches that avoid the use of soluble factors. Here, a material system capable of sustaining the growth of stem cells (maintaining stemness) and of promoting highly efficient differentiation upon external stimulation is described. Poly(ethyl acrylate) induces assembly of fibronectin (FN) into nanonetworks (FN fibrillogenesis) upon simple adsorption from solutions. It is shown that these FN nanonetworks allow growth of MSCs and maintenance of stemness for long periods of time (up to 30 d) using basal media in absence of soluble factors. Additionally, the system promotes enhanced levels of differentiation when defined supplemented media are used. The study reveals the critical role of the intermediate protein layer at the material interface to control MSC fate regardless of the properties of the underlying material and it introduces a new material system as a candidate to be used in MSC niche design. Engineered material‐based fibronectin interfaces support distinctive stem cell phenotypes. The material spontaneously induces fibronectin organization into nanonetworks, a biomimetic microenvironment, which maintains stemness under basal conditions and enhances cell differentiation upon external stimuli with defined media. Fibronectin nanonetworks are a versatile tool with potential use in fundamental stem cell research and regenerative medicine.
      PubDate: 2016-08-04T07:10:52.107317-05:
      DOI: 10.1002/adfm.201602333
       
  • A Luminescent Inorganic/Organic Composite Ultrathin Film Based on a 2D
           Cascade FRET Process and Its Potential VOC Selective Sensing Properties
    • Authors: Yumei Qin; Jingjing Shi, Xianggeng Gong, Zeyun Tian, Ping Zhang, Jun Lu
      Abstract: The cascade Förster resonance energy transfer (FRET) is a multiple step nonradiative process that occurs between more than one pair of energy donor and acceptor molecules on the scale less than 10 nm, and it has played an important role in developing fluorescence sensors because of its simplicity and sensitivity. Here, blue‐emitting neutral poly(vinyl carbazole), green‐emitting tris‐(8‐hydroxy‐quinoline) aluminum, tris[2‐(4,6‐difluorophenyl) pyridinato‐C2,N] iridium (III), and orange‐emitting 4‐(dicyano‐methylene)‐2‐methyl‐6‐(4‐dimethylamino‐styryl)‐4H‐pyran (DCM) are coassembled with layered double hydroxide nanosheets using a layer‐by‐layer method to form inorganic/organic composite luminescence ultrathin films (UTFs). The UV–vis absorption, scanning electron microscopy, and small‐angle X‐ray diffraction results demonstrate that the fabricated ultrathin films are ordered, linear growth, and homogeneous. The photoluminescence spectroscopy demonstrates that the 2D cascade FRET process is realized and a significant enhancement of light emission and extended lifetime of DCM dye is obtained in the UTF. Furthermore, these composite UTFs show fast, sensitive, and selective fluorescence signal patterns toward common volatile organic compounds (VOCs) based on interfering the 2D cascade FRET process, implying its potential application in the VOC selective sensing field. Luminescent inorganic/organic composite ultrathin films are fabricated using a layer‐by‐layer assembly method. The structure and fluorescence characterization of the PVK@Ir(F2ppy)3@4‐(dicyano‐methylene)‐2‐methyl‐6‐(4‐dimethylamino‐styryl)‐4H‐pyran (DCM)/layered double hydroxide (LDH) ultrathin films indicates the cascade Förster resonance energy transfer (FRET) process occurs in the 2D interlayer of LDHs and results in an enhanced and prolonged lifetime of DCM fluorescence. These films show sensitive and selective fluorescence signal patterns to volatile organic compound vapors by modulating the FRET process.
      PubDate: 2016-08-03T09:59:18.994016-05:
      DOI: 10.1002/adfm.201601087
       
  • Polyfluorinated Electrolyte for Fully Printed Carbon Nanotube Electronics
    • Authors: Huaping Li; Yifan Tang, Wenmin Guo, Hongyu Liu, Lili Zhou, Nina Smolinski
      Abstract: Flexible electronics with highly thermal stability and mechanical strength are highly needed in advanced transportation systems. Semiconducting single‐walled carbon nanotubes are one of the leading active materials for such thin film transistors because they are printable, flexible, thermally stable, and mechanically strong. Dielectrics with large capacitance are another major component, and polymer electrolytes are printed for flexible electronics, but they suffer from poor mechanical strength and low operating temperature. Here, a transparent, mechanically flexible, and thermally stable polyfluorinated electrolyte (PFE) is developed with high capacitance by curing printed polyfluorinated resin (PFR) and ionic liquid composite at high temperature. PFE inherits the mechanical flexibility and thermal stability from PFR. The immobilized ionic liquid inside the porous structures of PFE accounts for the high capacitance. With top‐gated PFE, fully printed electronically pure single‐chirality (6,5) single‐walled carbon nanotube (SWCNT) thin‐film transistors (TFTs) exhibit air stable, consistent, and reliable ambipolar characteristics with high transconductance (1 mS) and small subthreshold swing (105 ON/OFF current ratio for both carriers under low operation voltage. An air stable (6,5) single chirality single‐walled carbon nanotube (SWCNT) thin‐film transistor (TFT) backplane is fully printed on a light‐emitting diode (LED) array to drive LED pixels under 3 V. High‐performance fully printed (6,5) SWCNT TFTs exhibit ambipolar properties with high transconductance (1 mS) and small subthreshold swing (
      PubDate: 2016-08-03T09:59:14.164871-05:
      DOI: 10.1002/adfm.201601605
       
  • Patterning and Conductivity Modulation of Conductive Polymers by UV Light
           Exposure
    • Authors: Jesper Edberg; Donata Iandolo, Robert Brooke, Xianjie Liu, Chiara Musumeci, Jens Wenzel Andreasen, Daniel T. Simon, Drew Evans, Isak Engquist, Magnus Berggren
      Abstract: A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used to control the conductivity in the conjugated polymer poly(3,4‐ethylenedioxythiophene):tosylate by more than six orders of magnitude in addition to producing high‐resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well as the properties of the resulting polymer are investigated. A patterning technique for conductive polymers is demonstrated, based on UV light exposure through a photo mask followed by vapor phase polymerization. High‐resolution patterns and optical gradients in poly(3,4‐ethylenedioxythiophene):tosylate can be fabricated, where the conductivity is controlled over more than six orders of magnitude. Image of Albert Einstein used with permission © Philippe Halsman/Magnum Photos/IBL Bildbyrå.
      PubDate: 2016-08-03T09:59:08.057039-05:
      DOI: 10.1002/adfm.201601794
       
  • Tailoring Surface Acidity of Metal Oxide for Better Polysulfide Entrapment
           in Li‐S Batteries
    • Authors: Xiwen Wang; Tao Gao, Xiulin Fan, Fudong Han, Yiqing Wu, Zhian Zhang, Jie Li, Chunsheng Wang
      Abstract: The polysulfide shuttle reaction has severely limited practical applications of Li‐S batteries. Recently, functional materials that can chemically adsorb polysulfide show significant enhancement in cycling stability and Coulombic efficiency. However, the mechanism of the chemisorption and the control factors governing the chemisorption are still not fully understood. Here, it is demonstrated for the first time that the surface acidity of the host material plays a crucial role in the chemisorption of polysulfide. By tailoring the surface acidity of TiO2 via heteroatom doping, the polysulfide‐TiO2 interaction can be fortified and thus significantly the capacity fading be reduced to 0.04% per cycle. The discovery presented here sheds light on the mechanism of this interfacial phenomenon, and opens a new avenue that can lead to a practical sulfur/host composite cathode. Lewis acid based interaction between metal oxide host and polysulfide effectively confines polysulfides within metal oxide/sulfur cathodes. It is demonstrated that the overall electrochemical performance of lithium‐sulfur batteries can be greatly improved by tuning the surface acidity of metal oxide through the heteroatom doping.
      PubDate: 2016-08-03T09:58:59.097456-05:
      DOI: 10.1002/adfm.201602264
       
  • Constraining Si Particles within Graphene Foam Monolith: Interfacial
           Modification for High‐Performance Li+ Storage and Flexible
           Integrated Configuration
    • Abstract: Pulverization of electrode materials and loss of electrical contact have been identified as the major causes for the performance deterioration of alloy anodes in Li‐ion batteries. This study presents the hierarchical arrangement of spatially confining silicon nanoparticles (Si NPs) within graphene foam (GF) for alleviating these issues. Through a freeze‐drying method, the highly oriented GF monolith is engineered to fully encapsulate the Si NPs, serving not only as a robust framework with the well‐accessible thoroughfares for electrolyte percolation but also a physical blocking layer to restrain Si from direct exposure to the electrolyte. In return, the pillar effect of Si NPs prevents the graphene sheets from restacking while preserving the highly efficient electron/Li+ transport channels. When evaluated as a binder‐free anode, impressive cycle performance is realized in both half‐cell and full‐cell configurations. Operando X‐ray diffraction and in‐house X‐ray photoelectron spectroscopy confirm the pivotal protection of GF to sheathe the most volume‐expanded lithiated phase (Li15Si4) at room temperature. Furthermore, a free‐standing composite film is developed through readjusting the pore size in GF/Si monolith and directly integrated with nanocellulose membrane (NCM) separator. Because of the good electrical conductivity and structural integrity of the GF monolith as well as the flexibility of the NCM separator, the as‐developed GF/Si‐NCM electrode showcases the potential use in the flexible electronic devices. Si particles are spatially constrained within graphene foam monolith using a freeze‐drying method, and impressive Li+ storage capabilities are shown in both the half‐cell and the full‐cell. The presence of the deep lithiated phase, c‐Li15Si4 is confirmed by the prototype analysis of operando X‐ray diffraction (XRD) and in‐house X‐ray photoelectron spectroscopy (XPS) techniques. A flexible, metal‐free electrode based on the proposed integrated configuration is being developed.
      PubDate: 2016-08-03T09:58:55.821148-05:
      DOI: 10.1002/adfm.201602324
       
  • Channeled β‐TCP Scaffolds Promoted Vascularization and Bone
           Augmentation in Mandible of Beagle Dogs
    • Authors: Tao Yu; Qing Liu, Ting Jiang, Xuesong Wang, Yunzhi Yang, Yunqing Kang
      Abstract: A major hindrance to successful alveolar bone augmentation and ridge preservation using synthetic scaffolds is insufficient vascularization in the implanted bone grafts. The slow ingrowth of host vasculature from the bone bed of alveolar bone to the top of the implanted bone grafts leads to limited bone formation in the upper layers of the implanted grafts, which hinders the subsequent implantation of titanium dental implants. In this study, macroporous beta‐tricalcium phosphate (β‐TCP) scaffolds with multiple vertical hollow channels are fabricated that play a similar role as blood vessels for nutrient diffusion and cell migration. The results show that the hollow channels accelerate the degradation rate of the β‐TCP scaffolds and the in vitro release of a bone forming peptide‐1, which significantly promote proliferation and osteogenesis of human bone mesenchymal stem cells on the channeled scaffolds, compared to nonchanneled scaffolds in vitro. More volume of newly formed bone tissues with more blood vessels are augmented in the channeled scaffolds when implanted in mandibular bone defects of beagle dogs. Channeled scaffolds significantly promote new bone formation and augment the height of the mandible. These findings indicate channeled scaffolds facilitate vascularization and bone formation and have great potential for vascularized bone augmentation. A macroporous bioceramic scaffold with multiple channels produced by a unique template‐casting technique demonstrates excellent interconnected pores. The channeled scaffolds significantly promote cell proliferation, rapid vascularization, and new bone formation. The channeled scaffolds also maintain the height of formed bone tissue, which brings promising potential for mandibular bone augmentation.
      PubDate: 2016-08-03T09:58:52.159046-05:
      DOI: 10.1002/adfm.201602631
       
  • Synthesis of Ultrathin, Homogeneous Copolymer Dielectrics to Control the
           Threshold Voltage of Organic Thin‐Film Transistors
    • Authors: Kwanyong Pak; Hyejeong Seong, Junhwan Choi, Wan Sik Hwang, Sung Gap Im
      Abstract: This work demonstrates that threshold voltage (VT) of organic thin‐film transistors (OTFTs) can be controlled systematically by introducing new copolymer dielectrics with electropositive functionality. A series of homogeneous copolymer dielectrics are polymerized from two monomers, 1,3,5‐trimethyl‐1,3,5‐trivinyl cyclotrisiloxane (V3D3) and 1‐vinylimidazole (VI), via initiated chemical vapor deposition. The chemical composition of the copolymer dielectrics is exquisitely controlled to tune the VT of C60 OTFTs. In particular, all the copolymer dielectrics demonstrated in this work exhibit extremely low leakage current densities (lower than 2.5 × 10−8 A cm−2 at ±3 MV cm−1) even with a thickness less than 23 nm. Furthermore, by introducing an ultrathin pV3D3 interfacial layer (about 3 nm) between the copolymer dielectrics and C60 semiconductor, the high mobility of the C60 OTFTs (about 1 cm2 V−1 s−1) remains unperturbed, showing that VT can be controlled independently by tuning the composition of the copolymer dielectrics. Coupled with the ultralow dielectric thickness, the independent VT controllability allows the VT to be aligned near 0 V with sub‐3 V operating voltage, which enables a substantial decrease of device power consumption. The suggested method can be employed widely to enhance device performance and reduce power consumption in various organic integrated circuit applications. A series of new ultrathin copolymer dielectrics (sub‐23 nm) with different compositions is synthesized via initiated chemical vapor deposition to tune the threshold voltage (VT) of organic thin‐film transistors (OTFTs). By combining the copolymer dielectrics with an interfacial layer, the VT of C60 OTFT can be independently controlled according to the copolymer composition without any degradation of device performance.
      PubDate: 2016-08-03T09:58:38.991308-05:
      DOI: 10.1002/adfm.201602585
       
  • Mechanistic Insights on Ternary Ni2−xCoxP for Hydrogen Evolution and
           Their Hybrids with Graphene as Highly Efficient and Robust Catalysts for
           Overall Water Splitting
    • Abstract: Searching the high‐efficient, stable, and earth‐abundant electrocatalysts to replace the precious noble metals holds the promise for practical utilizations of hydrogen and oxygen evolution reactions (HER and OER). Here, a series of highly active and robust Co‐doped nickel phosphides (Ni2−xCoxP) catalysts and their hybrids with reduced graphene oxide (rGO) are developed as bifunctional catalysts for both HER and OER. The Co‐doping in Ni2P and their hybridization with rGO effectively regulate the catalytic activity of the surface active sites, accelerate the charge transfer, and boost their superior catalytic activity. Density functional theory calculations show that the Co‐doped catalysts deliver the moderate trapping of atomic hydrogen and facile desorption of the generated H2 due to the H‐poisoned surface active sites of Ni2−xCoxP under the real catalytic process. Electrochemical measurements reveal the high HER efficiency and durability of the NiCoP/rGO hybrids in electrolytes with pH 0–14. Coupled with the remarkable and robust OER activity of the NiCoP/rGO hybrids, the practical utilization of the NiCoP/rGO‖NiCoP/rGO for overall water splitting yields a catalytic current density of 10 mA cm−2 at 1.59 V over 75 h without an obvious degradation and Faradic efficiency of ≈100% in a two‐electrode configuration and 1.0 m KOH. Co‐doped nickel phosphide catalysts and their hybrids with reduced graphene oxide exhibit robust electrocatalytic activity toward both the hydrogen evolution reaction and the oxygen evolution reaction. Density functional theory calculations reveal that the Co chemical doping moderates trapping of atomic hydrogen and facile desorption of H2 when the most chemically active part of the surface is poisoned by hydrogen under the catalytic process.
      PubDate: 2016-08-02T08:21:32.63108-05:0
      DOI: 10.1002/adfm.201601420
       
  • Highly Efficient Coaxial TiO2‐PtPd Tubular Nanomachines for
           Photocatalytic Water Purification with Multiple Locomotion Strategies
    • Abstract: Titania is a promising photocatalyst for water purification or production of solar fuels. However, due to its large band gap, titania is photoactive solely under UV light, which accounts for less than 5% of the solar spectrum. In this work, TiO2‐based hybrid 1D nanostructures with photocatalytic activities extended to visible light region are designed and fabricated. Highly efficient coaxial TiO2‐PtPd‐Ni nanotubes (NTs) are fabricated by a template‐assisted electrochemical synthesis route for water remediation under UV light, visible light, and natural sunlight. These coaxial hybrid nanotubes display a 100% degradation of organic pollutant rhodamine B in only 50 min (k‐value 0.071 min−1) and 30 min under visible light and natural sunlight, respectively. For comparison, TiO2 nanotubes doped with Pd nanoparticles are also fabricated and they show inferior photocatalytic properties and degrading stability over time. The multicomponent design enables to actuate the hybrid NTs by using two different external energy sources, i.e., magnetic and acoustic fields. Self‐propelled, autonomous actuation in the presence of H2O2 is also realized. These versatile actuation modes have the potential to enable the reported photocatalytic nanomachines to work efficiently under complex environments and to be easily collected for reuse. Coaxial TiO2‐PtPd‐Ni hybrid nanotubes exhibit greatly enhanced visible light photocatalyic activity: a 100% degradation of organic pollutant under visible and natural sunlight with high stability. Combined with multiple locomotion strategies, these highly efficient and cost‐effective hybrid photocatalytic nanomachines have the potential to be reused for practical water remediation applications in complex and challenging environments.
      PubDate: 2016-08-02T08:21:23.692657-05:
      DOI: 10.1002/adfm.201602315
       
  • Efficient Lightweight Supercapacitor with Compression Stability
    • Authors: Kaiyuan Shi; Xuan Yang, Emily D. Cranston, Igor Zhitomirsky
      Abstract: This paper reports the fabrication of an electrochemical supercapacitor (ES) with high gravimetric and areal capacitances, achieved at a high mass ratio of active material to current collector. The active material, polypyrrole, is in situ polymerized in an aerogel‐based current collector composed of crosslinked cellulose nanocrystals (CNCs) and multiwalled carbon nanotubes (MWCNTs). Mechanical robustness, flexibility, and low impedance of the current collectors are achieved by the chemical crosslinking of CNC aerogels and efficient dispersion of MWCNTs through the use of bile acid as a dispersant. Furthermore, the advanced electrode design results in low contact resistance. A single‐electrode areal capacitance of 2.1 F cm−2 is obtained at an active mass loading of 17.8 mg cm−2 and an active material to current collector mass ratio of 0.57. Large area ES electrodes and devices show flexibility, excellent compression stability at 80% compression, and electrochemical cyclic stability over 5000 cycles. Moreover, good retention of capacitive properties is achieved at high charge–discharge rates and during compression cycling. The results of this investigation pave the way for the fabrication of advanced lightweight ES, which can be used for energy storage in wearable electronic devices and other applications. An electrochemical supercapacitor is developed with a new method, based on in‐situ polymerization of polypyrrole in a light weight current collector, composed of crosslinked cellulose nanocrystals and multiwalled carbon nanotubes. The supercapacitor shows high areal capacitance, good capacitance retention at high charge–discharge rates, high mass ratio of active material to current collector, cyclic stability, and excellent mechanical compressibility.
      PubDate: 2016-08-02T08:21:14.405637-05:
      DOI: 10.1002/adfm.201602103
       
  • The Capturing of Ionized Oxygen in Sodium Vanadium Oxide Nanorods Cathodes
           under Operando Conditions
    • Authors: Mengyu Yan; Luzi Zhao, Kangning Zhao, Qiulong Wei, Qinyou An, Guobin Zhang, Xiujuan Wei, Wenhao Ren, Liqiang Mai
      Abstract: The control of voltage window has been considered as a universal strategy in improving the cycling stability of cathode materials, which is supposed and explained by avoiding side reactions. To address the conjecture, the detailed structure evolution of Na0.76V6O15 nanorods is investigated with different electrochemical reaction voltage windows. High time resolution in situ X‐ray diffraction, ex situ X‐ray photoelectron spectroscopy, ex situ Raman spectroscopy, and transmission electron microscopy demonstrate the amorphization of Na0.76V6O15 nanorods and formation of ionized oxygen in nanorods, leading to the increased polarization voltage and fast capacity fading. The amorphization and diffusion of ionized oxygen in nanorods is controlled by optimizing the voltage window, resulting in the great increase of capacity retention from 26% to 80%. It is demonstrated that controlling the voltage window and corresponding ionized oxygen diffusion can mitigate the fast capacity fading to achieve long lasting lithium ion batteries. Here, the formation of ionized oxygen in sodium vanadium oxide nanorods is monitored through high time resolution in situ X‐ray diffraction and a series of ex situ measurements, and then it is suppressed by controlling the voltage window, which results in a great increase of capacity retention from 26% to 80%.
      PubDate: 2016-08-02T08:21:02.256982-05:
      DOI: 10.1002/adfm.201602134
       
  • Carbon Nanotubes Rooted in Porous Ternary Metal Sulfide@N/S‐Doped
           Carbon Dodecahedron: Bimetal‐Organic‐Frameworks Derivation and
           Electrochemical Application for High‐Capacity and Long‐Life
           Lithium‐Ion Batteries
    • Authors: Hao Li; Yun Su, Weiwei Sun, Yong Wang
      Abstract: Lithium ion battery is the predominant power source for portable electronic devices, electrical vehicles, and back‐up electricity storage units for clean and renewable energies. High‐capacity and long‐life electrode materials are essential for the next‐generation Li‐ion battery with high energy density. Here bimetal‐organic‐frameworks synthesis of Co0.4Zn0.19S@N and S codoped carbon dodecahedron is shown with rooted carbon nanotubes (Co‐Zn‐S@N‐S‐C‐CNT) for high‐performance Li‐ion battery application. Benefiting from the synergetic effect of two metal sulfide species for Li‐storage at different voltages, mesoporous dodecahedron structure, N and S codoped carbon overlayer and deep‐rooted CNTs network, the product exhibits a larger‐than‐theoretical reversible Li‐storage capacity of 941 mAh g−1 after 250 cycles at 100 mA g−1 and excellent high‐rate capability (734, 591, 505 mAh g−1 after 500 cycles at large current densities of 1, 2, and 5 A g−1 , respectively). Bimetal‐organic frameworks of a Co/Zn‐ZIF‐67 precursor are used to fabricate mesoporous Co‐Zn‐S dodecahedron with N and S co‐doped carbon overlayer and many small deep‐rooted carbon nanotubes, which delivers outstanding larger‐than‐theoretical reversible capacities with stable cyclability for lithium‐ion batteries.
      PubDate: 2016-08-01T07:50:35.624611-05:
      DOI: 10.1002/adfm.201601631
       
  • Urchin‐Like CoSe2 as a High‐Performance Anode Material for
           Sodium‐Ion Batteries
    • Abstract: Urchin‐like CoSe2 assembled by nanorods has been synthesized via simple solvothermal route and has been first applied as an anode material for sodium‐ion batteries (SIBs) with ether‐based electrolytes. The CoSe2 delivers excellent sodiation and desodiation properties when using 1 m NaCF3SO3 in diethyleneglycol dimethylether as an electrolyte and cycling between 0.5 and 3.0 V. A high discharge capacity of 0.410 Ah g−1 is obtained at 1 A g−1 after 1800 cycles, corresponding to a capacity retention of 98.6% calculated from the 30th cycle. Even at an ultrahigh rate of 50 A g−1, the capacity still maintains 0.097 Ah g−1. The reaction mechanism of the as‐prepared CoSe2 is also investigated. The results demonstrate that at discharged 1.56 V, insertion reaction occurs, while two conversion reactions take place at the second and third plateaus around 0.98 and 0.65 V. During the charge process, Co first reacts with Na2Se to form NaxCoSe2 and then turns back to CoSe2. In addition to Na/CoSe2 half cells, Na3V2(PO4)3/CoSe2 full cell with excessive amount of Na3V2(PO4)3 has been studied. The full cell exhibits a reversible capacity of 0.380 Ah g−1. This work definitely enriches the possibilities for anode materials for SIBs with high performance. Urchin‐like CoSe2 assembled by nanorods is prepared via a facile solvothermal route and delivers excellent Na‐storage properties for both Na/CoSe2 and Na3V2(PO4)3/CoSe2 batteries when using ether‐based electrolyte in a voltage range of 0.5−3.0 V. The long‐term cyclability and high‐rate capability are attributed to partial pseudocapacitive behaviors and stable electrolyte.
      PubDate: 2016-07-29T07:25:40.966472-05:
      DOI: 10.1002/adfm.201602608
       
  • Indoline‐Based Molecular Engineering for Optimizing the Performance
           of Photoactive Thin Films
    • Abstract: New indoline dyes (RK‐1–4) were designed with a planar geometry and high molar extinction coefficient, which provided surprising power conversion efficiency (PCE) with a thin titanium dioxide film in dye‐sensitized solar cells (DSCs). They had a difference in only alkyl chain length. Despite the same molecular structure, the performance of the respective DSCs varied significantly. Investigating the dye adsorption processes and charge transfer kinetics, the alkyl chain length was determined to affect the dye surface coverage as well as the recombination between the injected photoelectrons and the oxidized redox mediators. When applied to the DSCs as a light harvester, RK‐3 with the dodecyl group exhibited the best photocurrent density, consequently achieving the best PCE of 9.1% with a 1.8 μm active and 2.5 μm scattering layer because of the most favorable charge injection. However, when increasing the active layer thickness, overall device performance deteriorated and the charge collection and regeneration played major roles for determining the PCE. Therefore, RK‐2 featuring the highest surface coverage and moderate alkyl chain length obtained the highest PCEs of 8.8% and 7.9% with 3.5 and 5.1 μm active layers, respectively. These results present a promising perspective of organic dye design for thin film DSCs. New indoline derivatives characterized by good planarity and high molar absorptivity are successfully applied to dye‐sensitized solar cells (DSCs). By controlling the hydrocarbon chain length, noticeable photocurrent density is achieved at a very thin TiO2 film, which is traced elementally, guiding the research of organic dyes for thin film‐based DSCs.
      PubDate: 2016-07-28T08:45:38.594923-05:
      DOI: 10.1002/adfm.201600951
       
  • One‐Step Synthesis of Photoluminescent Covalent Polymeric
           Nanocomposites from 2D Silicon Nanosheets
    • Abstract: Herein, the synthesis and characterization of the first polymeric nanocomposite based on silicon nanosheets (SiNSs) are reported. In a one‐step reaction, the formation of the polymeric matrix material and simultaneous functionalization of the SiNSs with polymers occur via radical polymerization of organic monomers such as styrene, methyl methacrylate, and acrylic acid. Depending on the purification method used, a covalently linked nanocomposite or the functionalized SiNSs are obtained. SiNSs decompose when exposed to basic conditions or to UV light. The UV‐light‐based decomposition is briefly investigated. In the nanocomposite, the stability of the 2D nanomaterial enhances significantly against these external influences, while the optoelectronic properties (e.g., photoluminescence) of the SiNSs and the processing characteristics of the polymeric matrix are preserved. Silicon‐nanosheet‐based nanocomposites are synthesized in a one‐step reaction. The hybrid material exhibits the processing properties of the polymeric matrix and the optoelectronic properties of the silicon material. In addition, the polymer stabilizes the nanomaterial against external influences, providing an insight into the photodegradation processes of the silicon monolayers.
      PubDate: 2016-07-28T08:45:28.842009-05:
      DOI: 10.1002/adfm.201602137
       
  • Improved Morphology and Efficiency of Polymer Solar Cells by Processing
           Donor–Acceptor Copolymer Additives
    • Abstract: A novel wide‐bandgap conjugated polymer PBTA‐FPh based on benzodithiophene‐alt‐benzo[1,2,3]triazole as the main chain and a polar pentafluorothiophenyl (FPh) group in the side chain has been designed and synthesized. In comparison to the pristine polymer PBTA‐BO that consists of nonpolar alkyl side chains, the resulting PBTA‐FPh exhibits less pronounced aggregation while possessing analogous optical and electrochemical bandgaps. Contact angle measurements demonstrate that the surface energy can be enhanced by incorporating FPh moiety, leading to a better miscibility of PBTA‐BO with PC71BM in the presence of a certain amount of PBTA‐FPh. The photoactive layer of PBTA‐BO:PC71BM:PBTA‐FPh with weight ratio of 1:1.2:0.02% exhibits a percolated network with the fibrous features, as revealed by transmission electron microscopy measurements. Of particular interest is the significantly improved photovoltaic performances of polymer solar cell devices for which the power conversion efficiency is enhanced from 6.46% for the control device to 7.91% for device processed with PBTA‐FPh as the polymeric additive. These observations indicate that introducing donor–acceptor type of polymeric additive comprising of polar groups in the side chain can be a promising strategy for the fabrication of high‐performance polymer solar cells. A novel wide‐bandgap conjugated polymer PBTA‐FPh based on benzodithiophene‐alt‐benzo[1,2,3]triazole as the main chain and a polar pentafluorothiophenyl (FPh) group in a side chain has been designed and synthesized as a polymeric additive. The incorporation of PBTA‐FPh can lead to improved miscibility and morphology of PBTA‐BO:PC71BM blend films, resulting in obviously improved power conversion efficiency of polymer solar cells from 6.46% to 7.91%.
      PubDate: 2016-07-28T01:25:41.049683-05:
      DOI: 10.1002/adfm.201601625
       
  • Color Tuning of Avobenzone Boron Difluoride as an Emitter to Achieve
           Full‐Color Emission
    • Abstract: Organic light‐emitting diodes (OLEDs) displaying a wide range of emission colors with emission peaks from 450 to 665 nm using a single emitting material, avobenzone boron difluoride (AVB‐BF2), are reported. Color tuning is achieved by controlling the aggregation of AVB‐BF2 and the formation of a “triadic” exciplex of an AVB‐BF2 dimer and a host molecule. Various electroluminescent devices containing AVB‐BF2 cover the whole visible light spectrum and a white‐emitting device with CIE coordinates of (0.35, 0.37) is obtained with a single emitting material in a single emissive layer. Furthermore, an exceptionally high external quantum efficiency of nearly 13% is achieved for a green‐emitting OLED because AVB‐BF2 exhibits thermally activated delayed fluorescence by forming the exciplex. Full‐color‐tunable OLEDs that can also achieve white emission are demonstrated by using a single emitter and a single emissive layer through a new strategy exploiting both aggregation and exciplex formation. The aggregation formation induces emission color shift from blue to green. Further color shift to red is provided by the aggregation induced exciplex formation through the triadic exciplex formation between aggregated emitter and host molecules.
      PubDate: 2016-07-25T08:15:46.876688-05:
      DOI: 10.1002/adfm.201601257
       
  • Applied Voltage and Near‐Infrared Light Enable Healing of
           Superhydrophobicity Loss Caused by Severe Scratches in Conductive
           Superhydrophobic Films
    • Authors: Mengchun Wu; Yang Li, Ni An, Junqi Sun
      Abstract: The fabrication of self‐healing/healable superhydrophobic films that can conveniently and repeatedly restore the loss of superhydrophobicity caused by severe mechanical damage, such as deep and wide surface scratches, remains challenging. In the present work, conductive superhydrophobic films that are healable by means of an applied voltage or near infrared (NIR) light irradiation are fabricated by depositing a layer of Ag nanoparticles and Ag nanowires (AgNPs‐AgNWs) on a thermally healable polycaprolactone (PCL)/poly(vinyl alcohol) (PVA) composite film, followed by the deposition of 1H,1H,2H,2H‐perfluorodecanethiol. The AgNPs‐AgNWs layer not only provides micro‐ and nanoscaled hierarchical structures in support of superhydrophobicity but also serves as an electrothermal or photothermal heater to enable healing of the underlying PCL/PVA film under the assistance of a low applied voltage or low‐power NIR light irradiation. Because of the strong adhesion between the PCL/PVA film and the AgNPs‐AgNWs layer, the healability of the PCL/PVA film is successfully conveyed to the conductive superhydrophobic layer, which can rapidly and repeatedly restore the loss of superhydrophobicity caused by cuts several hundreds of micrometers wide. The combined electrothermal and superhydrophobic properties endow the healable conductive superhydrophobic films with improved durability and usefulness as self‐cleaning, antiicing, and snow‐removing surfaces. Heal thyself! Healable conductive superhydrophobic films are fabricated by depositing a conductive superhydrophobic layer containing Ag nanowires on a thermally healable polymer film. Under a low applied voltage or upon irradiation with low‐power near infrared light, Ag nanowires in the superhydrophobic films act as heaters to enable repeated and rapid restoration of lost superhydrophobicity caused by cuts or scratches several hundreds of micrometers wide.
      PubDate: 2016-07-25T08:15:37.596463-05:
      DOI: 10.1002/adfm.201601979
       
  • Mesoporous Piezoelectric Polymer Composite Films with Tunable Mechanical
           Modulus for Harvesting Energy from Liquid Pressure Fluctuation
    • Authors: Zhiyi Zhang; Chunhua Yao, Yanhao Yu, Zhanglian Hong, Mingjia Zhi, Xudong Wang
      Abstract: Harvesting mechanical energy from biological systems possesses great potential for in vivo powering implantable electronic devices. In this paper, a development of flexible piezoelectric nanogenerator (NG) is reported based on mesoporous poly(vinylidene fluoride) (PVDF) films. Monolithic mesoporous PVDF is fabricated by a template‐free sol–gel‐based approach at room temperature. By filling the pores of PVDF network with poly(dimethylsiloxane) (PDMS) elastomer, the composite's modulus is effectively tuned over a wide range down to the same level of biological systems. A close match of the modulus between NG and the surrounding biological component is critical to achieve practical integration. Upon deformation, the composite NG exhibits appreciable piezoelectric output that is comparable to or higher than other PVDF‐based NGs. An artificial artery system is fabricated using PDMS with the composite NG integrated inside. Effective energy harvesting from liquid pressure fluctuation (simulating blood pressure fluctuation) is successfully demonstrated. The simple and effective approach for fabricating mesoporous PVDF with tunable mechanical properties provides a promising route toward the development of self‐powered implantable devices. Flexible piezoelectric nanogenerator is developed using mesoporous poly(vinylidene fluoride)/poly(dimethylsiloxane) composite with tunable Young's moduli down to the level of biological systems. The high flexibility and elasticity, together with appreciable piezoelectric output, demonstrate a good potential for biomechanical energy harvesting from simulated blood pressure fluctuation.
      PubDate: 2016-07-25T08:15:27.205347-05:
      DOI: 10.1002/adfm.201602624
       
  • Nanostructured Antimony‐Doped Tin Oxide Layers with Tunable Pore
           Architectures as Versatile Transparent Current Collectors for
           Biophotovoltaics
    • Abstract: Nanostructured transparent conducting oxide (TCO) layers gain increasing importance as high surface area electrodes enabling incorporation of functional redox species with high loading. The fabrication of porous TCO films, namely, antimony‐doped tin oxide (ATO), is reported using the self‐assembly of preformed ATO nanocrystals with poly(ethylene oxide‐b‐hexyl acrylate) (PEO‐b‐PHA) block copolymer. The high molar mass of the polymer and tunable solution processing conditions enable the fabrication of TCO electrodes with pore sizes ranging from mesopores to macropores. Particularly notable is access to uniform macroporous films with a nominal pore size of around 80 nm, which is difficult to obtain by other techniques. The combination of tunable porosity with a large conducting interface makes the obtained layers versatile current collectors with adjustable performance. While all the obtained electrodes incorporate a large amount of small redox molecules such as molybdenum polyoxometalate, only the electrodes with sufficiently large macropores are able to accommodate high amounts of bulky photoactive photosystem I (PSI) protein complexes. The 11‐fold enhancement of the current response of PSI modified macroporous ATO electrodes compared to PSI on planar indium tin oxide (ITO), makes this type of electrodes promising candidates for the development of biohybrid devices. Nanostructured transparent conducting oxide layers with a tunable porosity are prepared via self‐assembly of antimony‐doped tin oxide nanoparticles and PEO‐b‐PHA polymer. The combination of adjustable pore sizes from 10 nm mesopores to 300 nm macropores with a large conducting interface makes the obtained layers versatile current collectors for bioelectronic devices incorporating large amounts of functional bioentities such as photosystem I.
      PubDate: 2016-07-25T01:16:12.05655-05:0
      DOI: 10.1002/adfm.201602148
       
  • Oxidation‐Resistant and Elastic Mesoporous Carbon with
           Single‐Layer Graphene Walls
    • Abstract: An oxidation‐resistant and elastic mesoporous carbon, graphene mesosponge (GMS), is prepared. GMS has a sponge‐like mesoporous framework (mean pore size is 5.8 nm) consisting mostly of single‐layer graphene walls, which realizes a high electric conductivity and a large surface area (1940 m2 g−1). Moreover, the graphene‐based framework includes only a very small amount of edge sites, thereby achieving much higher stability against oxidation than conventional porous carbons such as carbon blacks and activated carbons. Thus, GMS can simultaneously possess seemingly incompatible properties; the advantages of graphitized carbon materials (high conductivity and high oxidation resistance) and porous carbons (large surface area). These unique features allow GMS to exhibit a sufficient capacitance (125 F g−1), wide potential window (4 V), and good rate capability as an electrode material for electric double‐layer capacitors utilizing an organic electrolyte. Hence, GMS achieves a high energy density of 59.3 Wh kg−1 (material mass base), which is more than twice that of commercial materials. Moreover, the continuous graphene framework makes GMS mechanically tough and extremely elastic, and its mean pore size (5.8 nm) can be reversibly compressed down to 0.7 nm by simply applying mechanical force. The sponge‐like elastic property enables an advanced force‐induced adsorption control. Oxidation‐resistant and elastic mesoporous carbon consisting of single‐layer graphene walls is prepared. The unique framework realizes a large surface area and minimal number of edge sites, thereby making the material promising for the application in electric double‐layer capacitors. The framework is mechanically tough and greatly elastic, enabling an advanced force‐induced adsorption control.
      PubDate: 2016-07-21T08:25:09.485654-05:
      DOI: 10.1002/adfm.201602459
       
  • Ultrafast Plasmonic Hot Electron Transfer in Au Nanoantenna/MoS2
           Heterostructures
    • Authors: Ying Yu; Ziheng Ji, Shuai Zu, Bowen Du, Yimin Kang, Ziwei Li, Zhangkai Zhou, Kebin Shi, Zheyu Fang
      Abstract: 2D transition metal dichalcogenides are becoming attractive materials for novel photoelectric and photovoltaic applications due to their excellent optoelectric properties and accessible optical bandgap in the near‐infrared to visible range. Devices utilizing 2D materials integrated with metal nanostructures have recently emerged as efficient schemes for hot electron‐based photodetection. Metal‐semiconductor heterostructures with low cost, simple procedure, and fast response time are crucial for the practical applications of optoelectric devices. In this paper, template‐based sputtering method is used first to fabricate Au nanoantenna (NA)/MoS2 heterostructures with low cost, simple preparation, broad spectral response, and fast response time. Through the measurement of femtosecond pump‐probe spectroscopy, it is demonstrated that plasmon‐induced hot electron transfer takes place in the Au NA/MoS2 heterostructure on the order of 200 fs with an injected electron density of about 5.6 × 1012 cm−2. Moreover, the pump‐power‐dependent photoluminescence spectra confirm that the exciton energy of MoS2 can be enhanced, coupled, and reradiated by the Au NA. Such ultrafast plasmon‐induced hot electron transfer in the metal‐semiconductor heterostructure can enable novel 2D devices for light harvesting and photoelectric conversion. In this study, the femtosecond pump‐probe technique is used to measure electron transfer of the Au nanoantenna/MoS2 heterostructure, which is fabricated by the template‐based sputtering method with low cost and simple procedures. The results demonstrate that plasmon‐induced hot electron transfer takes place in the heterostructure in the order of 200 fs with an injected electron density of about 5.6 × 1012 cm−2.
      PubDate: 2016-07-21T08:21:44.867399-05:
      DOI: 10.1002/adfm.201601779
       
  • Broadband Photoresponse Enhancement of a High‐Performance t‐Se
           Microtube Photodetector by Plasmonic Metallic Nanoparticles
    • Authors: Kai Hu; Hongyu Chen, Mingming Jiang, Feng Teng, Lingxia Zheng, Xiaosheng Fang
      Abstract: Broadband responsivity enhancement of single Se microtube (Se‐MT) photodetectors in the UV–visible region is presented in this research. The pristine Se‐MT photodetector demonstrates broadband photoresponse from 300 to 700 nm with peak responsivity of ≈19 mA W−1 at 610 nm and fast speed (rise time 0.32 ms and fall time 23.02 ms). To further enhance the responsivity of the single Se‐MT photodetector, Au and Pt nanoparticles (NPs) are sputtered on these devices. In contrast to only enhancement of responsivity in UV region by Pt NPs, broadband responsivity enhancement (≈600% to ≈800%) of the Se‐MT photodetector is realized from 300 to 700 nm by tuning the size and density of Au NPs. The broadband responsivity enhancement phenomena are interpreted by both the surface modification and surface plasmon coupling. The experimental results of this work provide an additional opportunity for fabricating high‐performance UV–visible broadband photodetectors. A broadband photodetector based on a single Se microtube is demonstrated with responsivity of ≈19 mA W−1 at 610 nm and fast speed (rise time 0.32 ms and fall time 23.02 ms). The responsivity of this device is improved by Au nanoparticles via a simple sputtering method and (≈600% to ≈800%) responsivity enhancement is realized within broadband region (300–700 nm).
      PubDate: 2016-07-21T08:21:41.049266-05:
      DOI: 10.1002/adfm.201602408
       
  • Toward High‐Output Organic Vertical Field Effect Transistors: Key
           Design Parameters
    • Authors: Hyukyun Kwon; Mincheol Kim, Hyunsu Cho, Hanul Moon, Jongjin Lee, Seunghyup Yoo
      Abstract: The performance of C60‐based organic vertical field‐effect transistors (VFETs) is investigated as a function of key geometrical parameters to attain a better understanding of their operation mechanism and eventually to enhance their output current for maximal driving capability. To this end, a 2D device simulation is performed and compared with experimental results. The results reveal that the output current scales mostly with the width of its drain electrode, which is in essence equivalent to the channel width in conventional lateral‐channel transistors, but that of the source electrode and the thickness of C60 layers underneath the source electrode also play subtle but important roles mainly due to the source contact‐limited behavior of the organic VFETs under study. With design strategies acquired from this study, a VFET with an on/off ratio of 5.5 × 105 and on‐current corresponding to a channel length of near 1 μm in a conventional lateral‐channel organic field‐effect transistor (FET) is demonstrated, while the drain width of the VFET and the channel width of the lateral‐channel organic FET are the same. The operation mechanism and performance of organic vertical field effect transistors (VFETs) have been investigated. Several key factors are identified such as source/drain electrode widths, source contact resistance, and bottom active layer thickness. With the key parameters, the proposed VFET shows greater performance than conventional organic field‐effect transistors with lateral channel in terms of driving capability.
      PubDate: 2016-07-21T08:10:45.084875-05:
      DOI: 10.1002/adfm.201601956
       
  • Direct Heating Amino Acids with Silica: A Universal Solvent‐Free
           Assembly Approach to Highly Nitrogen‐Doped Mesoporous Carbon
           Materials
    • Authors: Xingmin Gao; Zhi Chen, Yan Yao, Mengyuan Zhou, Yong Liu, Jinxiu Wang, Winston Duo Wu, Xiao Dong Chen, Zhangxiong Wu, Dongyuan Zhao
      Abstract: A general solvent‐free assembly approach via directly heating amino acid and mesoporous silica mixtures is developed for the synthesis of a family of highly nitrogen‐doped mesoporous carbons. Amino acids have been used as the sole precursors for templating synthesis of a series of ordered mesoporous carbons. During heating, amino acids are melted and strongly interact with silica, leading to effective loading and improved carbon yields (up to ≈25 wt%), thus to successful structure replication and nitrogen‐doping. Unique solvent‐free structure assembly mechanisms are proposed and elucidated semi‐quantitatively by using two affinity scales. Significantly high nitrogen‐doping levels are achieved, up to 9.4 (16.0) wt% via carbonization at 900 (700) °C. The diverse types of amino acids, their variable interactions with silica and different pyrolytic behaviors lead to nitrogen‐doped mesoporous carbons with tunable surface areas (700–1400 m2 g−1), pore volumes (0.9–2.5 cm3 g−1), pore sizes (4.3–10 nm), and particle sizes from a single template. As demonstrations, the typical nitrogen‐doped carbons show good performance in CO2 capture with high CO2/N2 selectivities up to ≈48. Moreover, they show attractive performance for oxygen reduction reaction, with an onset and a half‐wave potential of ≈−0.06 and −0.14 V (vs Ag/AgCl). A universal solvent‐free assembly approach via directly heating amino acid/mesoporous silica mixture is developed for the synthesis of a family of nitrogen‐doped mesoporous carbons with tunable physicochemical properties. The underlying structure assembly mechanisms are elucidated by using two affinity scales. The nitrogen contents are among the highest in literature, rendering them efficient for sorption and catalysis.
      PubDate: 2016-07-21T07:40:47.977551-05:
      DOI: 10.1002/adfm.201601640
       
  • Stabilizing Active Edge Sites in Semicrystalline Molybdenum Sulfide by
           Anchorage on Nitrogen‐Doped Carbon Nanotubes for Hydrogen Evolution
           Reaction
    • Abstract: Finding an abundant and cost‐effective electrocatalyst for the hydrogen evolution reaction (HER) is crucial for a global production of hydrogen from water electrolysis. This work reports an exceptionally large surface area hybrid catalyst electrode comprising semicrystalline molybdenum sulfide (MoS2+x) catalyst attached on a substrate based on nitrogen‐doped carbon nanotubes (N‐CNTs), which are directly grown on carbon fiber paper (CP). It is shown here that nitrogen‐doping of the carbon nanotubes improves the anchoring of MoS2+x catalyst compared to undoped carbon nanotubes and concurrently stabilizes a semicrystalline structure of MoS2+x with a high exposure of active sites for HER. The well‐connected constituents of the hybrid catalyst are shown to facilitate electron transport and as a result of the good attributes, the MoS2+x/N‐CNT/CP electrode exhibits an onset potential of −135 mV for HER in 0.5 m H2SO4, a Tafel slope of 36 mV dec−1, and high stability at a current density of −10 mA cm−2. This study reports on how an unusually high number of active edge sites in semicrystalline molybdenum sulfide can be stabilized by anchorage on nitrogen‐doped carbon nanotubes. The hybrid electrode performs well for hydrogen evolution reactions.
      PubDate: 2016-07-21T01:20:43.678438-05:
      DOI: 10.1002/adfm.201601994
       
  • Electrocatalysis: Mo Doping Induced More Active Sites in Urchin‐Like
           W18O49 Nanostructure with Remarkably Enhanced Performance for Hydrogen
           Evolution Reaction (Adv. Funct. Mater. 32/2016)
    • Pages: 5769 - 5769
      Abstract: On page 5778, J.‐G. Wang and co‐workers present a 3D urching‐like Mo‐W18O49 catalyst that exhibits a small onset potential and Tafel slope in catalyzing hydrogen evolution reaction (HER). Synergies between an increased amount of active sites and activity improvement by Mo doping as well as a high surface area cause the performance enhancement. Scalable, highly efficient Mo‐W18O49 HER electrocatalysts obtained via this simple doping strategy are promising for future water splitting devices.
      PubDate: 2016-08-22T09:07:34.257331-05:
      DOI: 10.1002/adfm.201670204
       
  • Photoporation: A Universal Platform for Macromolecular Deliveryinto Cells
           Using Gold Nanoparticle Layers via the Photoporation Effect (Adv. Funct.
           Mater. 32/2016)
    • Authors: Zhonglin Lyu; Feng Zhou, Qi Liu, Hui Xue, Qian Yu, Hong Chen
      Pages: 5770 - 5770
      Abstract: Q. Yu, H. Chen, and co‐workers demonstrate on page 5787 a universal and cost‐effective platform using gold nanoparticle layers (GNPLs) as photoporation reagent for delivering various biomacromolecules into diverse cells with high efficiency, high‐throughput, and low cell cytotoxicity, showing great potential for various applications, including manipulation of cellular processes, gene silencing, detection, and treatment of diseases.
      PubDate: 2016-08-22T09:07:36.554079-05:
      DOI: 10.1002/adfm.201670205
       
  • Contents: (Adv. Funct. Mater. 32/2016)
    • Pages: 5771 - 5777
      PubDate: 2016-08-22T09:07:34.144299-05:
      DOI: 10.1002/adfm.201670207
       
  • Mo Doping Induced More Active Sites in Urchin‐Like W18O49
           Nanostructure with Remarkably Enhanced Performance for Hydrogen Evolution
           Reaction
    • Pages: 5778 - 5786
      Abstract: Exploring highly efficient and inexpensive hydrogen evolution reaction (HER) electrocatalysts for various electrochemical energy conversion technologies is actively encouraged. Herein, a 3D urchin‐like Mo‐W18O49 nanostructure as an efficient HER catalyst is reported for the first time. The obtained Mo‐W18O49 catalyst exhibits excellent electrocatalytic activity toward HER with small onset potential and Tafel slope. The prepared Mo‐W18O49 electrode shows excellent durability after a long period. Density functional theory calculations reveal that the remarkably enhanced performance of Mo‐W18O49 can be due to the ability of Mo dopant to increase the number of active sites, leading to optimal hydrogen adsorption on the active sites because of the electronic and geometric modulation. In addition, the urchin‐like 3D morphology with a high surface area and abundant 1D nanowires promotes electron transfer, thereby ensuring fast interfacial charge transfer to improve electrocatalytic reactions. All these experimental and theoretical results clearly reveal that Mo‐W18O49 intrinsically improves HER activity and thus has potential applications in water splitting. The 3D urchin‐like Mo‐W18O49 catalyst exhibits excellent electrocatalytic activity toward HER with small onset potential and Tafel slope, as well as excellent durability. The remarkably enhanced performance of Mo‐W18O49 can be ascribed to the synergistic effect of an increased amount of active sites and of activity improvment by Mo dopant, furthermore abundant agminated 1D nanowires also provide a high surface area.
      PubDate: 2016-07-01T05:41:46.147001-05:
      DOI: 10.1002/adfm.201601732
       
  • A Universal Platform for Macromolecular Deliveryinto Cells Using Gold
           Nanoparticle Layers via the Photoporation Effect
    • Authors: Zhonglin Lyu; Feng Zhou, Qi Liu, Hui Xue, Qian Yu, Hong Chen
      Pages: 5787 - 5795
      Abstract: Although promising, it is challenging to develop a simple and universal method for the high‐efficiency delivery of biomacromolecules into diverse cells. Here, a universal delivery platform based on gold nanoparticle layer (GNPL) surfaces is proposed. Upon laser irradiation, GNPL surfaces show such good photothermal properties that absorption of the laser energy causes a rapid increase in surface temperature, leading to enhanced membrane permeability of the cultured cells and the diffusion of macromolecules into the cytosol from the surrounding medium. The high‐efficiency delivery of different macromolecules such as dextran and plasmid DNA into different cell types is achieved, including hard‐to‐transfect mouse embryonic fibroblasts (mEFs) and human umbilical vein endothelial cells (HUVECs), while cell viability is well maintained under optimized irradiation conditions. The platform vastly outperforms the leading commercial reagent, Lipofectamine 2000, especially in transfecting hard‐to‐transfect cell lines (plasmid transfection efficiency: ≈53% vs ≈19% for mEFs and ≈44% vs ≈8% for HUVECs). Importantly, as the gold nanoparticles (GNPs) constituting the GNPL are firmly immobilized together, the potential cytotoxicity caused by endocytosis of GNPs is effectively avoided. This platform is reliable, efficient, and cost‐effective with high‐throughput and broad applicability across different cell types, opening up an innovative avenue for high‐efficiency intracellular delivery. A universal platform using gold nanoparticle layer (GNPL) as the photoporation reagent for macromolecular delivery is proposed. It achieves the high‐efficiency delivery of different macromolecules into various cell types, including hard‐to‐transfect cells. Importantly, as the gold nanoparticles (GNPs) that constitute the GNPL are firmly immobilized together, the potential cytotoxicity caused by endocytosis of GNPs is effectively avoided.
      PubDate: 2016-06-07T05:41:18.553178-05:
      DOI: 10.1002/adfm.201602036
       
  • Highly Selective Ionic Transport through Subnanometer Pores in Polymer
           Films
    • Authors: Qi Wen; Dongxiao Yan, Feng Liu, Mao Wang, Yun Ling, Pengfei Wang, Patrick Kluth, Daniel Schauries, Christina Trautmann, Pavel Apel, Wei Guo, Guoqing Xiao, Jie Liu, Jianming Xue, Yugang Wang
      Pages: 5796 - 5803
      Abstract: Novel transport phenomena through nanopores are expected to emerge as their diameters approach subnanometer scales. However, it has been challenging to explore such a regime experimentally. Here, this study reports on polymer subnanometer pores exhibiting unique selective ionic transport. 12 μm long, parallel oriented polymer nanopores are fabricated in polyethylene terephthalate (PET) films by irradiation with GeV heavy ions and subsequent 3 h exposure to UV radiation. These nanopores show ionic transport selectivity spanning more than 6 orders of magnitude: the order of the transport rate is Li+>Na+>K+>Cs+>>Mg2+>Ca2+>Ba2+, and heavy metal ions such as Cd2+ and anions are blocked. The transport can be switched off with a sharp transition by decreasing the pH value of the electrolyte. Structural measurements and molecular dynamics simulations suggest that the ionic transport is attributed to negatively charged nanopores with pore radii of ≈0.3 nm, and the selectivity is associated with the dehydration effect. Negatively charged subnanometer pores are fabricated in polymer films by GeV heavy ions irradiation without chemical etching. Their selective ionic transport rates span more than 6 orders of magnitude and follow the rarely observed Eisenman sequence XI.
      PubDate: 2016-07-01T05:41:57.727144-05:
      DOI: 10.1002/adfm.201601689
       
  • Bioengineered Extracellular Membranous Nanovesicles for Efficient
           Small‐Interfering RNA Delivery: Versatile Platforms for Stem Cell
           Engineering and In Vivo Delivery
    • Pages: 5804 - 5817
      Abstract: Naturally derived nanovesicles secreted from various cell types and found in body fluids can provide effective platforms for the delivery of various cargoes because of their intrinsic ability to be internalized for intercellular signal transmission and membrane recycling. In this study, the versatility of bioengineered extracellular membranous nanovesicles as potent carriers of small‐interfering RNAs (siRNAs) for stem cell engineering and in vivo delivery has been explored. Here, exosomes have been engineered, one of the cell‐derived vesicle types, to overexpress exosomal proteins fused with cell‐adhesion or cell‐penetrating peptides for enhanced intracellular gene transfer. To devise a more effective delivery system with potential for mass production, a new siRNA delivery system has also been developed by artificially inducing the outward budding of plasma membrane nanovesicles. Those nanovesicles have been engineered by overexpressing E‐cadherin to facilitate siRNA delivery to human stem cells with resistance to intracellular gene transfer. Both types of engineered nanovesicles deliver siRNAs to human stem cells for lineage specification with negligible cytotoxicity. The nanovesicles are efficient in delivering siRNA in vivo, suggesting feasibility for gene therapy. Cell‐derived, bioengineered nanovesicles used for siRNA delivery can provide functional platforms enabling effective stem cell therapeutics and in vivo gene therapy. Two types of cell‐derived, bioengineered nanovesicles are explored as versatile small‐interfering RNA (siRNA) delivery carriers for stem cell engineering and in vivo delivery. These siRNA delivery systems inspired by their intrinsic role in gene transfer are demonstrated to be highly efficient in guiding lineage specification of human stem cells with negligible cytotoxicity in vitro and are efficient in delivery of siRNA in vivo with marginal hepatotoxicity.
      PubDate: 2016-06-14T01:21:15.882816-05:
      DOI: 10.1002/adfm.201601430
       
  • Optically Deformable Materials: Photoinduced Topographical Feature
           Development in Blueprinted Azobenzene‐Functionalized Liquid
           Crystalline Elastomers (Adv. Funct. Mater. 32/2016)
    • Pages: 5818 - 5818
      Abstract: The photoinduced topographical deformation of azobenzene‐functionalized liquid crystalline elastomers is reported by T.J. White and co‐workers on page 5819. The authors report on the use of UV light irradiation to transform originally flat sheets into topographical surfaces. The photoinduced shape transformation and relaxation is shown to strongly depend on the azobenzene concentration as well as the network structure.
      PubDate: 2016-08-22T09:07:33.676175-05:
      DOI: 10.1002/adfm.201670208
       
  • Photoinduced Topographical Feature Development in Blueprinted
           Azobenzene‐Functionalized Liquid Crystalline Elastomers
    • Pages: 5819 - 5826
      Abstract: All‐optical deformation and recovery of complex topographical features is demonstrated within elastic sheets composed of main‐chain type azobenzene‐functionalized liquid crystalline elastomers (azo‐LCEs). The azo‐LCEs are synthesized via an orthogonal, two‐step reaction between commercially available LC monomers and n‐butylamine. By employing surface alignment, the local orientation of the nematic director is spatially complex (“blueprinted”). Exposing the blueprinted LCE films to light as an actinic stimulus generates a photomechanical response which yields reversible shape changes between 2D and 3D shapes. The deformation of azo‐LCEs strongly depends on the azobenzene concentration as well as the network structure (i.e., crosslink density). Blueprinting complex director profiles within azo‐LCEs yield reconfigurable elastic sheets that can be addressed both remotely and selectively which may have benefit in a variety of applications in aerospace, medicine, and optics. All‐optical deformation and recovery of complex 3D topographical features that can be addressed both remotely and selectively is demonstrated in blueprinted azobenzene‐functionalized liquid crystalline elastomers. The photoinduced shape transformation strongly depends on the azobenzene concentration as well as the network structure (i.e., crosslink density).
      PubDate: 2016-07-15T06:02:27.63572-05:0
      DOI: 10.1002/adfm.201601090
       
  • Void Engineering in Metal–Organic Frameworks via Synergistic Etching
           and Surface Functionalization
    • Authors: Ming Hu; Yi Ju, Kang Liang, Tomoya Suma, Jiwei Cui, Frank Caruso
      Pages: 5827 - 5834
      Abstract: The rational design and engineering of metal–organic framework (MOF) crystals with hollow features has been used for various applications. Here, a top‐down strategy is established to construct hollow MOFs via synergistic etching and surface functionalization by using phenolic acid. The macrosized cavities are created inside various types of MOFs without destroying the parent crystalline framework, as evidenced by electron microscopy and X‐ray diffraction. The modified MOFs are simultaneously coated by metal–phenolic films. This coating endows the MOFs with the additional functionality of responding to near infrared irradiation to produce heat for potential photothermal therapy applications. A top‐down strategy to construct various hollow metal–organic frameworks (MOFs) is reported via synergistic etching and surface functionalization by using phenolic acid. Simultaneous surface modification not only allows precise etching inside the MOFs, but also results in a metal–phenolic coating on the MOFs. The metal–phenolic coating endows the MOFs with near infrared laser responsiveness.
      PubDate: 2016-06-09T13:33:15.99486-05:0
      DOI: 10.1002/adfm.201601193
       
  • Training Neural Stem Cells on Functional Collagen Scaffolds for Severe
           Spinal Cord Injury Repair
    • Authors: Xing Li; Sumei Liu, Yannan Zhao, Jiayin Li, Wenyong Ding, Sufang Han, Bing Chen, Zhifeng Xiao, Jianwu Dai
      Pages: 5835 - 5847
      Abstract: Neural stem cells (NSCs) transplantation is regarded as a promising therapeutic strategy to treat severe spinal cord injury (SCI) by compensating the neuronal loss. However, significant challenges including long‐term survival, directed neuronal differentiation, and functional integration of the transplanted NSCs and their progenies within the host spinal cord are yet to be solved. In this study, NSCs are trained on differently modified collagen scaffolds to increase their neuronal differentiation rate when cultured under the simulated SCI microenvironment. Then, a functional scaffold is screened out, on which the cultured NSCs show high neuronal differentiation rate and generate both sensory and motor mature neurons. Subsequently, that NSC seeded functional scaffold is transplanted into a rat severe SCI model. The results show that higher endogenous neurogenesis efficiency as well as in vivo survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, both sensory and motor neurons are found to be differentiated from the grafted NSCs in the lesion site and those newly generated neurons can functionally interact with each other and the host neurons. Taken together, the in vitro training systems for modulating the differentiation profiles of NSCs are instructive and exhibit strong potentials for SCI treatments. Neural stem cells (NSCs) trained on the functional collagen scaffolds achieve comparatively high neuronal differentiation rate and generate both sensory and motor mature neurons. After transplanting the NSCs seeded functional scaffold into a rat severe spinal cord injury model, higher survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, the grafted NSCs can generate sensory and motor neurons throughout the lesion site.
      PubDate: 2016-06-09T13:23:44.944494-05:
      DOI: 10.1002/adfm.201601521
       
  • Hierarchical Nanohybrids of Gold Nanorods and PGMA‐Based Polycations
           for Multifunctional Theranostics
    • Pages: 5848 - 5861
      Abstract: Organic/inorganic nanohybrids hold great importance in fabricating multifunctional theranostics to integrate therapeutic functions with real‐time imaging. Although Au nanorods (NRs) have been employed for theranostics, complicated design of materials limits their practical applications. In this work, new multifunctional theranostic agents are designed and synthesized employing Au NRs with desirable near‐infrared absorbance as the cores. A facile “grafting‐onto” approach is put forward to prepare the series of hierarchical nanohybrids (Au‐PGEA and Au‐PGED) of Au NRs and poly(glycidyl methacrylate)‐based polycations. The resultant nanohybrids can be utilized as gene carriers with high gene transfection performances. The structural effect of polycations on gene transfection is investigated in detail, and Au‐PGEA with abundant hydroxyl groups on the surface exhibits superior performance. Au‐PGEA nanohybrids are further validated to possess remarkable capability of combined photothermal therapy (PTT) and gene therapy (GT) for complementary tumor treatment. Moreover, significantly enhanced computed tomography (CT)/photoacoustic (PA) signals are detected both in vitro and in vivo, verifying the potential of Au‐PGEA for dual‐modal imaging with precise and accurate information. Therefore, these multifunctional nanohybrids fabricated from a simple and straightforward strategy are promising for in vivo dual‐modal CT/PA imaging guided GT/PTT therapy with high antitumor efficacy. Novel hierarchical nanohybrids of Au nanorods and poly(glycidyl methacrylate)‐based polycations are proposed for in vivo dual‐modal computed tomography/photoacoustic imaging guided gene therapy/photothermal therapy with high antitumor efficacy.
      PubDate: 2016-06-09T13:24:13.244441-05:
      DOI: 10.1002/adfm.201601418
       
  • Phosphorus‐Doped Perovskite Oxide as Highly Efficient Water
           Oxidation Electrocatalyst in Alkaline Solution
    • Authors: Yinlong Zhu; Wei Zhou, Jaka Sunarso, Yijun Zhong, Zongping Shao
      Pages: 5862 - 5872
      Abstract: Developing cost‐effective and efficient electrocatalysts for oxygen evolution reaction (OER) is of paramount importance for the storage of renewable energies. Perovskite oxides serve as attractive candidates given their structural and compositional flexibility in addition to high intrinsic catalytic activity. In a departure from the conventional doping approach utilizing metal elements only, here it is shown that non‐metal element doping provides an another attractive avenue to optimize the structure stability and OER performance of perovskite oxides. This is exemplified by a novel tetragonal perovskite developed in this work, i.e., SrCo0.95P0.05O3– δ (SCP) which features higher electrical conductivity and larger amount of O2 2−/O− species relative to the non‐doped parent SrCoO3– δ (SC), and thus shows improved OER activity. Also, the performance of SCP compares favorably to that of well‐developed perovskite oxides reported. More importantly, an unusual activation process with enhanced activity during accelerated durability test (ADT) is observed for SCP, whereas SC delivers deactivation for the OER. Such an activation phenomenon for SCP may be primarily attributed to the in situ formation of active A‐site‐deficient structure on the surface and the increased electrochemical surface area during ADT. The concept presented here bolsters the prospect to develop a viable alternative to precious metal‐based catalysts. Phosphorus‐doped perovskite oxide SrCo0.95P0.05O3– δ (SCP) is demonstrated for the first time as a high‐efficient oxygen evolution reaction (OER) electrocatalyst in alkaline solution. The SCP exhibits enhanced OER activity and stability compared to parent SrCoO3– δ (SC). More importantly, an activation process is observed for SCP during accelerated durability test, which primarily originates from the in situ formed Sr‐deficient layer on its surface.
      PubDate: 2016-06-09T13:22:19.237019-05:
      DOI: 10.1002/adfm.201601902
       
  • Multi‐Material Tissue Engineering Scaffold with Hierarchical Pore
           Architecture
    • Authors: Kathy Ye Morgan; Demetra Sklaviadis, Zachary L. Tochka, Kristin M. Fischer, Keith Hearon, Thomas D. Morgan, Robert Langer, Lisa E. Freed
      Pages: 5873 - 5883
      Abstract: Multi‐material polymer scaffolds with multiscale pore architectures are characterized and tested with vascular and heart cells as part of a platform for replacing damaged heart muscle. Vascular and muscle scaffolds are constructed from a new material, poly(limonene thioether) (PLT32i), which meets the design criteria of slow biodegradability, elastomeric mechanical properties, and facile processing. The vascular–parenchymal interface is a poly(glycerol sebacate) (PGS) porous membrane that meets different criteria of rapid biodegradability, high oxygen permeance, and high porosity. A hierarchical architecture of primary (macroscale) and secondary (microscale) pores is created by casting the PLT32i prepolymer onto sintered spheres of poly(methyl methacrylate) (PMMA) within precisely patterned molds followed by photocuring, de‐molding, and leaching out the PMMA. Prefabricated polymer templates are cellularized, assembled, and perfused in order to engineer spatially organized, contractile heart tissue. Structural and functional analyses show that the primary pores guide heart cell alignment and enable robust perfusion while the secondary pores increase heart cell retention and reduce polymer volume fraction. A biodegradable elastomeric polymer template with slowly and rapidly degrading components and a hierarchical architecture of primary (macroscale) and secondary (microscale) pores enables heart and vascular cells to form organized engineered cardiac tissue. The platform supports microvessel perfusion and contractile heart muscle formation in vitro and, if validated in vivo, may aid in the regenerative repair of vascularized tissues.
      PubDate: 2016-06-13T08:15:53.05358-05:0
      DOI: 10.1002/adfm.201601146
       
  • Anomalous Anisotropic Magnetoresistance of Antiferromagnetic Epitaxial
           Bimetallic Films: Mn2Au and Mn2Au/Fe Bilayers
    • Pages: 5884 - 5892
      Abstract: Recently intensive efforts have been devoted to the emerging field of antiferromagnetic (AFM) spintronics, where ferromagnetic electrodes are substituted by antiferromagnets. This study investigates the anisotropic magnetoresistance (AMR) of epitaxial tetragonal antiferromagnetic bimetallic films: Mn2Au and Mn2Au/Fe bilayers. An anomalous AMR effect with additional peaks is observed. This study theoretically and experimentally demonstrates that the AFM spins of Mn2Au can be viewed and controlled at room temperature, and this is achievable with a notably relatively small magnetic field of 200 mT. Strong hybridization between Au and Mn, and strong modification of the intrinsic quadratic anisotropy of Mn2Au from interfacial biquadratic anisotropy result in an additional anomalous AMR component of 1%. The findings suggest that Mn2Au films can be used in room temperature antiferromagnetic spintronics. Mn2Au, a bimetallic antiferromagnet, is considered an interesting high Néel temperature candidate within the emerging field of antiferromagnetic spintronic devices. An anomalous anisotropic magnetoresistance effect is observed with four peaks, persisting to room‐temperature for a field as low as 200 mT, demonstrating how Mn2Au spins can be viewed and controlled at room‐temperature and offering a route to room‐temperature antiferromagnetic spintronics.
      PubDate: 2016-06-22T11:21:28.962955-05:
      DOI: 10.1002/adfm.201601348
       
  • Sulfur‐Enriched Conjugated Polymer Nanosheet Derived Sulfur and
           Nitrogen co‐Doped Porous Carbon Nanosheets as Electrocatalysts for
           Oxygen Reduction Reaction and Zinc–Air Battery
    • Pages: 5893 - 5902
      Abstract: Among the rising 2D soft materials, conjugated polymer nanosheets are one of the most promising and new classes of polymeric materials, which are rarely developed because of the challenge in controlling the dimensionality and lack of synthetic strategies. In this study, one kind of sulfur‐enriched conjugated polymer nanosheet (2DP‐S) with a high aspect ratio of up to ≈400 is successfully synthesized. On the basis of structural characterization, as‐prepared 2DP‐S possesses the chemical identity of cruciform‐fused polymeric backbone consisting of quinoidal polythiophene and poly(p‐phenylenevinylene) along horizontal and vertical directions, respectively, by sharing two alternating single–double carbon–carbon bonds in each repeat unit. The unique structural conformation of 2DP‐S renders carrier mobilities of up to 0.1 ± 0.05 cm2 V−1 s−1, a figure inferred from Terahertz time domain spectroscopy. Moreover, upon thermal treatment, 2DP‐S is readily converted into N/S dual‐doped porous carbon nanosheets (2DPCs) under ammonia atmosphere, whose N/S ratio can be rationally controlled by adjusting the activation time. The catalytic performance of the oxygen reduction reaction of as‐prepared 2DPCs is well tunable by the rationally controlled N/S contents. These results offer a new pathway for exploring heteroatom‐doped porous carbons applicable for energy conversion and storage. A sulfur‐enriched conjugated polymer nanosheet (2DP‐S) with a high aspect ratio of up to ≈400 is synthesized using a conventional solution method. With three types of common conjugated materials, as‐prepared 2DP‐S exhibits a surprisingly high carrier mobility. 2DP‐S is further used as carbon precursor for the preparation of porous carbon nanosheets (2DPCs) with rationally controlled N/S ratio.
      PubDate: 2016-06-22T11:21:10.944585-05:
      DOI: 10.1002/adfm.201602158
       
  • Healing All‐Inorganic Perovskite Films via Recyclable
           Dissolution–Recyrstallization for Compact and Smooth Carrier
           Channels of Optoelectronic Devices with High Stability
    • Authors: Xiaoming Li; Dejian Yu, Fei Cao, Yu Gu, Yi Wei, Ye Wu, Jizhong Song, Haibo Zeng
      Pages: 5903 - 5912
      Abstract: The strong ionic character endows all‐inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) with different chemical features from classical Cd‐based NCs, especially when considering their interaction with polar solvents and surfactants. This has aroused intensive interest, but is still short of comprehensive understanding. More significantly, above characteristic may be used to improve the quality of perovskite thin films, which is crucial for the carrier transport inside optoelectronic devices. Here, an interesting recyclable dissolution–recyrstallization phenomenon of all‐inorganic pervoskite, as well as its application on room temperature (RT) self‐healing of compact and smooth carrier channels in ambient atmosphere for high‐performance PDs with high stability is reported. First, according to solubility equilibrium principle, the size of CsPbBr3 crystals can be reversibly tuned in the range of 10 nm–1 μm through washing with polar solvent or stirring with assistance of surfactants at RT. Second, such phenomenon is applied for significant film quality improvement by forming a liquid circumstance within films, which can transport matter at surface and sharp parts into the gaps, healing themselves at RT. This strategy results in large‐area, crack‐free, low‐roughness perovskite thin films. Obviously, such improvement facilitates transport and extraction of carriers in the channels of devices, which has been evidenced by the improvement of performances of the corresponding PDs at ambient condition. An interesting surface chemical phenomenon of all‐inorganic perovskite—recyclable dissolution and recrystallization—is reported, which is applied to build compact and smooth carrier channels for optoelectronic devices via self‐healing under ambient condition. The advantages of this film treating strategy are convinced by the improved responsivity, external quantum efficiency, response speed, and stability of photodetectors.
      PubDate: 2016-06-14T05:41:06.086327-05:
      DOI: 10.1002/adfm.201601571
       
  • Impact of the Nature of the Side‐Chains on the
           Polymer‐Fullerene Packing in the Mixed Regions of Bulk
           Heterojunction Solar Cells
    • Pages: 5913 - 5921
      Abstract: Polymer‐fullerene packing in mixed regions of a bulk heterojunction solar cell is expected to play a major role in exciton‐dissociation, charge‐separation, and charge‐recombination processes. Here, molecular dynamics simulations are combined with density functional theory calculations to examine the impact of nature and location of polymer side‐chains on the polymer‐fullerene packing in mixed regions. The focus is on poly‐benzo[1,2‐b:4,5‐b′]dithiophene‐thieno[3,4‐c]pyrrole‐4,6‐dione (PBDTTPD) as electron‐donating material and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as electron‐accepting material. Three polymer side‐chain patterns are considered: i) linear side‐chains on both benzodithiophene (BDT) and thienopyrroledione (TPD) moieties; ii) two linear side‐chains on BDT and a branched side‐chain on TPD; and iii) two branched side‐chains on BDT and a linear side‐chain on TPD. Increasing the number of branched side‐chains is found to decrease the polymer packing density and thereby to enhance PBDTTPD–PC61 BM mixing. The nature and location of side‐chains are found to play a determining role in the probability of finding PC61BM molecules close to either BDT or TPD. The electronic couplings relevant for the exciton‐dissociation and charge‐recombination processes are also evaluated. Overall, the findings are consistent with the experimental evolution of the PBDTTPD–PC61BM solar‐cell performance as a function of side‐chain patterns. Polymer side‐chains are expected to play a significant role in determining the polymer‐fullerene packing in the mixed regions of bulk‐heterojunction solar cells. The computational work, based on a combination of molecular dynamics simulations and density functional theory calculations, provides a detailed description of the impact that the nature and locations of the polymer side‐chains have on the nanoscale polymer‐fullerene packing.
      PubDate: 2016-06-20T06:20:58.168175-05:
      DOI: 10.1002/adfm.201601134
       
  • Fullerene‐Free Polymer Solar Cells with Open‐Circuit Voltage
           above 1.2 V: Tuning Phase Separation Behavior with Oligomer to Replace
           Polymer Acceptor
    • Authors: Yingying Fu; Bei Wang, Jianfei Qu, Yang Wu, Wei Ma, Yanhou Geng, Yanchun Han, Zhiyuan Xie
      Pages: 5922 - 5929
      Abstract: This study has proposed to use a well‐defined oligomer F4TBT4 to replace its analogue polymer as electron acceptor toward tuning the phase separation behavior and enhancing the photovoltaic performance of all‐polymer solar cells. It has been disclosed that the oligomer acceptor favors to construct pure and large‐scale phase separation in the polymer:oligomer blend film in contrast to the polymer:polymer blend film. This gets benefit from the well‐defined structure and short rigid conformation of the oligomer that endows it aggregation capability and avoids possible entanglement with the polymer donor chains. The charge recombination is to some extent suppressed and charge extraction is also improved. Finally, the P3HT:F4TBT4 solar cells not only output a high VOC above 1.2 V, but also achieve a power conversion efficiency of 4.12%, which is two times higher than the P3HT:PFTBT solar cells and is comparable to the P3HT:PCBM solar cells. The strategy of constructing optimum phase separation with oligomer to replace polymer opens up new prospect for the further improvement of the all‐polymer solar cells. A well‐defined oligomer F4TBT4 is proposed to replace its polymer PFTBT as electron acceptor to fabricate fullerene‐free polymer solar cells. The oligomer acceptor favors to construct pure and large‐scale phase separation in polymer blend film due to decreased chain entanglement. The resulted P3HT:F4TBT4 solar cells not only output a high VOC above 1.2 V, but also achieve a PCE of 4.12%.
      PubDate: 2016-06-17T10:46:23.33398-05:0
      DOI: 10.1002/adfm.201601880
       
  • Anion Acceptors Dioxaborinane Contained in Solid State Polymer
           Electrolyte: Preparation, Characterization, and DFT Calculations
    • Authors: Ping Yuan; Chuanlin Cai, Jiayong Tang, Yuqi Qin, Mengyuan Jin, Yanbao Fu, Zhenhua Li, Xiaohua Ma
      Pages: 5930 - 5939
      Abstract: A novel dioxaborinane‐contained solid state polymer electrolyte poly((2‐phenyl‐1, 3, 2‐dioxaborolane‐4‐yl) methyl methacrylate) (P(GMMA‐PBA)) for symmetrical capacitors (SCs) is prepared through solution casting technique. Due to the effect of electron withdrawing of dioxaborinane groups and irregular distributed porous microstructures, the solid polymer electrolyte (SPE) exhibits an optimal ionic conductivity of 0.5 mS cm−1 at ambient conditions. The electronic properties of dioxaborinane groups and their interaction with anions of electrolyte salts are further studied with density functional theory calculations. SCs fabricated with this polymer film as electrolyte and reduced graphene oxide as electrodes provide a broad potential window of 2.5 V. The energy density of this capacitor ups to 22.49 Wh kg−1 with a power density of 6.34 kW kg−1 at 5 A g−1. After 3000 charge–discharge cycles, the capacitance of the symmetrical SPE capacitor maintains 90% of its initial values. Dioxaborinane‐contained polymer electrolytes are successfully prepared for supercapacitors through solution casting technique. Density functional theory calculations are conducted by electronic structure, basis set superposition error and natural bond orbital analyses to confirm the effect of coordination between heterocyclic borane groups and perchlorate ion. The obtained anion receptor polymer electrolytes present higher electrochemical properties compared to polyethylene oxide‐based electrochemical storage capacitors.
      PubDate: 2016-06-14T05:20:35.352403-05:
      DOI: 10.1002/adfm.201600888
       
  • Efficient Piezoelectric Energy Harvesters Utilizing (001) Textured Bimorph
           PZT Films on Flexible Metal Foils
    • Pages: 5940 - 5946
      Abstract: Extracting energy from low vibration frequencies (
      PubDate: 2016-06-07T05:45:24.241459-05:
      DOI: 10.1002/adfm.201601347
       
  • Selective Ionic Transport: Highly Selective Ionic Transport through
           Subnanometer Pores in Polymer Films (Adv. Funct. Mater. 32/2016)
    • Authors: Qi Wen; Dongxiao Yan, Feng Liu, Mao Wang, Yun Ling, Pengfei Wang, Patrick Kluth, Daniel Schauries, Christina Trautmann, Pavel Apel, Wei Guo, Guoqing Xiao, Jie Liu, Jianming Xue, Yugang Wang
      Pages: 5947 - 5947
      Abstract: Polymer nanopores have great potential for ultrafiltration, desalination, and energy conversion because of their robustness, flexibility, and efficiency in large‐scale production. Yet a challenge in controlling the size to subnanometer limits their performance. F. Liu, Y. Wang, and co‐workers describe on page 5796, the generation of negatively charged subnanometer polymer pores that exhibit ultra‐high ionic transport selectivity and a unique order as Li+>Na+>K+>Cs+≫Mg2+>Ca2+>Ba2+≫blocked heavy metal ions and anions.
      PubDate: 2016-08-22T09:07:34.804717-05:
      DOI: 10.1002/adfm.201670209
       
  • Nanovesicles: Bioengineered Extracellular Membranous Nanovesicles for
           Efficient Small‐Interfering RNA Delivery: Versatile Platforms for
           Stem Cell Engineering and In Vivo Delivery (Adv. Funct. Mater. 32/2016)
    • Pages: 5948 - 5948
      Abstract: On page 5804, S.‐W. Cho and co‐workers propose cell‐derived bioengineered extracellular membranous nanovesicles as a novel small‐interfering RNA (siRNA) delivery system, and explore their potencies for stem cell engineering and in vivo delivery. Modification of these nanovesicles via overexpression of various target peptides or proteins on plasma membrane significantly improves siRNA delivery for enhanced differentiation in several types of human stem cells and potential therapeutic applications in vivo.
      PubDate: 2016-08-22T09:07:38.762716-05:
      DOI: 10.1002/adfm.201670210
       
 
 
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