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Journal Cover Journal of Polymer Science Part A: Polymer Chemistry
  [SJR: 1.037]   [H-I: 123]   [133 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0360-6376 - ISSN (Online) 1099-0518
   Published by John Wiley and Sons Homepage  [1589 journals]
  • Diphenylphenacyl sulfonium salt as dual photoinitiator for free radical
           and cationic polymerizations
    • Authors: Kerem Kaya; Johannes Kreutzer, Yusuf Yagci
      Abstract: Diphenylphenacylsulfonium tetrafluoroborate (DPPS+BF4–) salt possessing both phenacyl and sulfonium structural units was synthesized and characterized. DPPS+BF4– absorbs light at relatively higher wavelengths. The direct and sensitized initiation activity of the salt in both cationic and free radical photopolymerizations was investigated and compared with that of its analogue triphenylsulfonium tetrafluoroborate (TPS+BF4–). Differential scanning photocalorimetry and conventional gravimetric studies revealed that DPPS+BF4– showed higher efficiency for direct and sensitized photopolymerizations of most of the monomers investigated. Although, principally both homolytic and/or heterolytic cleavage is possible, theoretical studies suggested that homolytic pathway is more favored for the generation of reactive initiating species. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017A new photoinitiator having two chromophore groups (arylsulfonium and phenacyl units) was synthesized and proved to have superior absorbance characteristics and photoactivity over its triphenyl sulfonium analogue in both free radical and cationic polymerizations. The new initiator polymerizes the common monomers more efficiently and faster than its triphenyl analogue.
      PubDate: 2017-12-04T20:25:35.126253-05:
      DOI: 10.1002/pola.28918
       
  • Cover Image, Volume 56, Issue 2
    • Abstract: On page 174, Y. M. Chen and colleagues demonstrated the synthesis of cylindrical bottlebrushes grafted with poly(2-oxazoline) via the grafting onto method. The resulting bottlebrushes exhibited uni-molecular nanoparticles of different shapes, depending on the length of their backbones. The image shows worm-like nanoparticles of a number average length up to 188 nm. Furthermore, the lower critical solution temperature of thermoresponsive bottlebrushes with poly(2-ethyl-2-oxazoline) as side chain increased with increasing the hydrophobic backbone length. (
      DOI : 10.1002/pola.28889)
      PubDate: 2017-12-02T07:22:07.389014-05:
       
  • Direct arylation synthesis of thienoisoindigo-based low-band-gap polymer
           from asymmetric donor–acceptor monomer
    • Authors: Kazuhiro Nakabayashi; Haruka Fukuzawa, Karin Fujita, Hideharu Mori
      Abstract: Thienoisoindigo (TIG) moiety has been paid numerous attentions as an excellent acceptor building block in low-band-gap polymers. Herein, a new TIG-dithiophene alternating copolymer (PTIG2T) was successfully synthesized from an asymmetric TIG-based donor–acceptor (D-A) monomer via the self-condensation-type direct arylation polymerization. PTIG2T exhibited the light absorption over 1000 nm owing to the intramolecular charge transfer in the thin film state, which corresponded to an optical band gap of 1.24 eV. The HOMO and LUMO levels of PTIG2T were determined to be −5.08 and −3.60 eV, respectively. Furthermore, the organic photovoltaic (OPV) with a PTIG2T/PC61BM active layer achieved a power conversion efficiency (PCE) of 3.19%, which is one of the highest PEC achieved by OPVs with TIG-based materials. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017A new thienoisoindigo (TIG)-based low-band-gap polymer (PTIG2T) was successfully synthesized from an asymmetric TIG-based donor–acceptor (D-A) monomer via the self-condensation-type direct arylation polymerization. Furthermore, an organic photovoltaic using PTIG2T as a donor material was investigated in detail.
      PubDate: 2017-11-30T01:40:42.903032-05:
      DOI: 10.1002/pola.28912
       
  • Semi-interpenetrating polymer networks based on crosslinked
           poly(N-isopropyl acrylamide) and methylcellulose prepared by frontal
           polymerization
    • Authors: A. Mariani; L. Nuvoli, D. Sanna, V. Alzari, D. Nuvoli, M. Rassu, G. Malucelli
      Abstract: In this work, semi-interpenetrating gels of poly(N-isopropyl acrylamide) and methylcellulose were successfully synthesized by using the Frontal Polymerization (FP) technique. The gels were obtained in the presence of dimethyl sulfoxide and trihexyltetradecylphosphonium persulfate, as polymerization solvent and radical initiator, respectively, hence avoiding the formation of bubbles during polymerization. Then, some of the gels containing dimethyl sulfoxide were thoroughly washed with water, hence obtaining the corresponding hydrogels. The effects of the ratio between poly(N-isopropyl acrylamide) and methylcellulose, the amount of crosslinker and solvent medium (i.e., dimethyl sulfoxide and water) were thoroughly studied, assessing the influence of temperature and velocity of FP fronts on the glass transition temperature values (dried samples), on the swelling behavior and on the dynamic-mechanical properties (gels swollen both in water and dimethyl sulfoxide). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.The Frontal Polymerization technique was exploited to obtain polymer materials based on poly(N-isopropyl acrylamide) and methylcellulose. In the form of hydrogel, the former is a well-known polymer exhibiting a responsive behavior as a consequence of temperature variation, while the latter is derived from renewable sources and available in large amounts. The materials resulting from their combination prepared in this work show interesting and peculiar properties that can be useful in biomedical applications.
      PubDate: 2017-11-28T04:33:51.467866-05:
      DOI: 10.1002/pola.28914
       
  • Selective ethylene oligomerization with in-situ-generated chromium
           catalysts supported by trifluoromethyl-containing ligands
    • Authors: Eung Man Choi; Jong-Eun Park, Gyeong Su Park, Bonggeun Shong, Sung Kwon Kang, Kyung-sun Son
      Abstract: A series of pyrrole-containing diarylphosphine and diarylphosphine oxide ligands were prepared. The catalytic activity of the corresponding in-situ-generated chromium catalysts was investigated during selective ethylene oligomerization reactions. Variations in the ligand system were introduced by modifying the diarylphosphine and pyrrole moieties that affect the steric and electronic properties. Minor changes in the ligand structure and the composition of activators significantly changed the catalytic activity, selectivity toward linear alpha-olefins (LAO) versus polyethylene (PE), and the distribution of oligomeric products. The presence of trifluoromethyl groups on the diphenyl rings in ligand 3 promoted oxidation to form the corresponding phosphine oxide structure, 3o, which dramatically enhanced the catalytic activity of ethylene trimerization. The in-situ-generated chromium complex based on 3o activated by DMAO (dry methylaluminoxane)/TIBA (triisobutylaluminum) was used to achieve activity of about 1250 g (mmol of Cr)−1 h−1 with 98.5 mol % 1-hexene, along with a negligible amount of PE side product. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.In-situ-generated chromium catalysts bearing a series of pyrrolyl-diarylphosphine and -diarylphosphine oxide ligands were prepared, and their influence on catalytic activity during selective ethylene oligomerization was studied. The ligand scaffold was varied by modifying the diarylphosphine substituents and the oxidation level of phosphine, which improved activity and selectivity for 1-hexene formation.
      PubDate: 2017-11-26T03:40:40.993046-05:
      DOI: 10.1002/pola.28915
       
  • Synthesis and electrochromic performance of oligoaniline-containing
           polyureas capped with various functional groups
    • Authors: Yanyan Li; Yan Zhou, Xiaoteng Jia, Xincai Liu, Ce Wang, Danming Chao
      Abstract: Tuning the molecular structure is an effective strategy to modulate the electrochromic behaviors of conducting polymers. In this contribution, a novel oligoaniline-containing polyurea ended with reactable isocyanate groups is designed and synthesized via nucleophilic polymerization. Then various functional groups such as o-toluidine, poly(ethylene glycol) (PEG), ethoxysilane, and congo red (CR) are introduced as end groups to modulate the electrochromic performance. Hydrophilic PEG could improve the switching speed due to the rapid electrolyte ions diffusion into polymer film through the hydrophilic region. An enhanced switching stability is afforded by crosslinkable ethoxysilane end groups, ascribed to crosslinked densified surface and great adhesion force between the electrochromic layer and ITO substrate through the hydrolysis reaction. Moreover, an ample color change is achieved by introducing colored CR as end groups. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017This article demonstrates the successful design and synthesis of a series of electrochromic polyureas capped with o-toluidine, PEG, ethoxysilane, and congo red end groups, respectively. The electrochromic properties, including color change, coloration efficiency, switching speed, and stability, have been effectively modulated.
      PubDate: 2017-11-22T00:00:52.227661-05:
      DOI: 10.1002/pola.28908
       
  • Self-assembly of block copolymers with an alkoxysilane-based core-forming
           block: A comparison of synthetic approaches
    • Authors: Guo Hui Teo; Rhiannon P. Kuchel, Per B. Zetterlund, Stuart C. Thickett
      Abstract: Polymerization-induced self-assembly (PISA) has become the preferred method of preparing self-assembled nano-objects based on amphiphilic block copolymers. The PISA methodology has also been extended to the realization of colloidal nanocomposites, such as polymer–silica hybrid particles. In this work, we compare two methods to prepare nanoparticles based on self-assembly of block copolymers bearing a core-forming block with a reactive alkoxysilane moiety (3-(trimethoxysilyl)propyl methacrylate, MPS), namely (i) RAFT emulsion polymerization using a hydrophilic macroRAFT agent and (ii) solution-phase self-assembly upon slow addition of a selective solvent. Emulsion polymerization under both ab initio and seeded conditions were studied, as well the use of different initiating systems. Effective and reproducible chain extension (and hence PISA) of MPS via thermally initiated RAFT emulsion polymerization was compromised due to the hydrolysis and polycondensation of MPS occurring under the reaction conditions employed. A more successful approach to block copolymer self-assembly was achieved via polymerization in a good solvent for both blocks (1,4-dioxane) followed by the slow addition of water, yielding spherical nanoparticles that increased in size as the length of the solvophobic block was increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.Aqueous self-assembly of diblock copolymers that have an alkoxysilane-functional group was studied. Two different synthesis methods, namely polymerization-induced self-assembly (PISA) and addition of a selective solvent, yielded greatly different results for the preparation of polymer nanostructures. Due to hydrolytic instability of the monomer in water, PISA proved unsuccessful. Preformed polymers in an organic solvent were successfully used to form self-assembled nanospheres via slow addition of water.
      PubDate: 2017-11-21T23:26:59.016475-05:
      DOI: 10.1002/pola.28911
       
  • Synthesis and thermal properties of linear polydicyclopentadiene via
           ring-opening metathesis polymerization with a third generation grubbs-type
           ruthenium-alkylidene complex
    • Authors: Nicholas D. Steese; Dhruv Barvaliya, Xavier D. Poole, Donald E. McLemore, John C. DiCesare, Hans-Jörg Schanz
      Abstract: Linear polydicyclopentadiene was produced with a third generation Grubbs-type Ru–alkylidene complex. At high catalyst loadings, the polymer shows a portion of the polymer with a low degree of branching owing to secondary ROCM as seen in the SEC analysis. Distinct signals are observed via low angle scattering analysis for polymers with twice or another multiple of the average molecular weight of the linear polymer hence strongly affecting the controlled-living nature of the polymerization.
      PubDate: 2017-11-21T23:26:48.184987-05:
      DOI: 10.1002/pola.28909
       
  • Assembly of a self-complementary monomer: Formation of a pH-responsive
           pillar[5]arene-based supramolecular polymer†
    • Authors: Zhihua Zhang; Li Shao, Jie Yang
      Abstract: A novel pH-responsive supramolecular polymer driven by CH…π interactions between alkyl chain and the cavity of pillar[5]arene was efficiently constructed in water.
      PubDate: 2017-11-21T23:26:44.932224-05:
      DOI: 10.1002/pola.28907
       
  • Double thermoresponsive block–random copolymers with adjustable phase
           transition temperatures: From block-like to gradient-like behavior
    • Authors: Steffen Eggers; Tilman Eckert, Volker Abetz
      Abstract: Stimuli-responsive block–random copolymers are very useful “smart” materials as their switching behavior can be tuned by simply adjusting the composition of the random copolymer block. Because of that, we synthesized double thermoresponsive poly(N-acryloylpyrrolidine)-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine) (PAPy-b-P(APi-co-APy)) copolymers via reversible addition fragmentation chain transfer (RAFT) polymerization and investigated their temperature-induced self-assembly in aqueous solution. By varying the APi/APy ratio in the random copolymer block, its phase transition temperature (PTT1) can indeed be precisely adjusted while the temperature-induced collapse upon heating leads to a fully reversible well-defined micellization. By making the two blocks compositionally similar to more than 60%, the polymers' mechanistic thermoresponsiveness can furthermore be changed from block-like to rather gradient-like behavior. This means the micellization onset at PTT1 and the corona collapse at the PTT of the more hydrophilic pure PAPy block (PTT2) overlap resulting in one single broad transition. This work thus contributes to the detailed understanding of design, synthesis and mechanistic behavior of tailored “on-demand” switchable materials. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.In this work, an example for the design and synthesis of smart on-demand materials is presented. The discussed block copolymers show a precisely and easily adjustable temperature-induced micellization in water. Besides the micellization temperature, the mechanistic behavior of the system can be switched from block-like (unimers–micelles–clusters) to gradient-like (unimers–broad transition to clusters). With this, it offers appealing options to adapt its temperature response to the requirements of specific applications.
      PubDate: 2017-11-19T07:35:42.834476-05:
      DOI: 10.1002/pola.28906
       
  • Dithienosilole–phenylquinoxaline-based copolymers with A-D-A-D and A-D
           structures for polymer solar cells
    • Authors: M. L. Keshtov; A. R. Khokhlov, S. A. Kuklin, A. Yu Nikolaev, E. N. Koukaras, Ganesh. D. Sharma
      Abstract: Two copolymers having D-A-D-A (P1) and D-A (P2) structures with quinoxaline acceptor unit and dithienosilole donor unit were synthesized and their optical and electrochemical (both experimental and theoretical) properties were investigated. The optical properties showed that these copolymers P1 and P2 exhibit optical bandgaps of 1.54 and 1.62 eV, respectively, with broader absorption profiles extending up to 800 nm and 770 nm, respectively. The electrochemical investigation of these two copolymers indicates that they exhibit suitable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels for efficient exciton dissociation and high open circuit voltage in the resultant polymer solar cells (PSCs). These copolymers were used as donors along with the PC71BM as acceptor for the fabrication of solution processed bulk heterojunction PSCs. The optimized P1:PC71BM and P2:PC71BM active layers treated with solvent vapor treatment showed overall power conversion efficiency (PCE) of 7.16% and 6.57%, respectively. The higher PCE of P1-based device as compared to P2 might be attributed to higher crystallinity of P1 and good hole mobility resulting more balanced charge transport. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017The strategy of using donor (D) and acceptor (A) conjugated copolymers with alternating electron rich and electron deficient units is effective in achieving high-performing solar cells. Two copolymers having D- A-D-A (P1) and D-A (P2) quinoxaline acceptor units and a dithienosilole donor unit were used as a donor along with PC71BM as an acceptor for polymer solar cells (PSCs). The optimized PSCs based on P1:PC71BM and P2:PC71BM active layers achieved power conversion efficiencies (PCE) of 7.16% and 6.57%, respectively. The PCE for P1 is attributed to higher crystallinity of P1 and good hole mobility, resulting in a more balanced charge transport.
      PubDate: 2017-11-17T03:51:10.479636-05:
      DOI: 10.1002/pola.28904
       
  • The microstructure determination of ethylene-styrene-propylene terpolymers
           at triad level by high-temperature two-dimensional NMR spectra
    • Authors: Ying-Yun Long; Yong-Xia Wang, Bai-Xiang Li, Yan-Guo Li, Yue-Sheng Li
      Abstract: To further extend temperature range of application and low temperature performance of the ethylene-styrene copolymers, a series of poly(ethylene-styrene-propylene) samples with varying monomer compositions and relatively low glass-transition temperatures (Tg = −28 – 22 °C) were synthesized by Me2Si(Me4Cp)(N-t-Bu)TiCl2/MMAO system. Since the 13C NMR spectra of the terpolymers were complex and some new resonances were present, 2D-1H/13C heteronuclear single quantum coherence and heteronuclear multiple bond correlation experiments were conducted. A complete 13C NMR characterization of these terpolymers was performed qualitatively and quantitatively, including chemical shifts, triad sequence distributions, and monomer average sequence lengths. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.A series of ethylene-styrene-propylene terpolymers with varying monomer compositions and relatively low glass-transition temperatures (Tg = −28 – 22 °C) were synthesized. With the help of 2D-1H/13C HSQC-DEPT and HMBC experiments, a complete 13C NMR characterization of these complex terpolymers was performed qualitatively and quantitatively, including chemical shifts, triad sequence distributions, and monomer average sequence lengths.
      PubDate: 2017-11-15T21:15:44.649388-05:
      DOI: 10.1002/pola.28903
       
  • Structural characterization of polybutadiene synthesized via cationic
           mechanism
    • Authors: Victor A. Rozentsvet; Olesya A. Stotskaya, Valentina P. Ivanova, Marianna G. Kuznetsova, Peter M. Tolstoy, Sergei V. Kostjuk
      Abstract: The microstructure of polybutadiene synthesized via cationic polymerization using TiCl4-based initiating systems has been investigated using 1D (1Н, 2Н, and 13С) and 2D (HSQC and HMBC) NMR spectroscopy. It was found that trans-1,4-unit is predominant structure of unsaturated part of polymer chain. Besides, the small amount of 1,2-structures was also detected, while cis-1,4-units were totally absent. The signals of carbon atoms of three types of head groups (trans-1,4-, 1,2-, and tert-butyl) and two types of end groups (trans-1,4-Cl and 1,2-Cl) were identified for the first time in macromolecules of cationic polybutadiene. It was showed that tert-butyl head groups were formed due to the presence in monomer of admixtures of isobutylene. The new methodology for calculation of the content of different structural units in polybutadiene chain as well as the head and end groups was proposed. It was established that main part of 1,2-units distributed randomly along the polybutadiene chain as separate units between trans-1,4-structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.The assignment of all signals in NMR spectra to carbon and hydrogen atoms of cationic polybutadiene (CPB) has been made for the first time. Particularly, it was found that trans-1,4-units are predominant structure, while 1,2-units are presented in minor amounts and cis-1,4-units are totally absent. The signals of atoms of three types of head-groups (trans-1,4-, 1,2-, and tert-butyl) and two types of end-groups (trans-1,4-Cl and 1,2-Cl) were identified in microstructure of CPB.
      PubDate: 2017-11-14T06:00:43.110063-05:
      DOI: 10.1002/pola.28905
       
  • Utilizing thiol–ene chemistry for crosslinked nickel cation-based
           anion exchange membranes
    • Authors: Michael T. Kwasny; Liang Zhu, Michael A. Hickner, Gregory N. Tew
      Abstract: Metal cation-based anion exchange membranes (AEMs) are a unique class of materials that have shown potential to be highly stable AEMs with competitive conductivities. Here, we expand upon previous work to report the synthesis of crosslinked nickel cation-based AEMs formed using the thiol–ene reaction. These thiol–ene-based samples were first characterized for their morphology, both with and without nickel cations, where the nickel-containing membranes demonstrated a disordered scattering peak characteristic of ionic clusters. The samples were then characterized for their water uptake, chemical and mechanical stability, and conductivity. They showed a combination of high water content and extreme brittleness, which also resulted in fairly low conductivity. The brittleness resulted from large water swelling as well as the need for each nickel cation to act as a crosslinker, necessary with the current nickel-coordination chemistry. Therefore, increasing the ion exchange capacity (IEC) for these types of AEMs, important for enhancing conductivity, also increased the crosslink density. The low conductivity and brittleness seen in this work demonstrated the need to develop non-crosslinking metal-complexes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.Nickel cation-based anion exchange membranes are synthesized using the thiol–ene reaction. These networks demonstrate the robustness of thiol–ene chemistry, as well as the excellent chemical stability of the resulting thioether and nickel cation moieties. In addition, ionic clusters are formed upon the addition of nickel cations. The trade-off between metal content and crosslink density is also exemplified, as high metal content membranes result in brittle mechanical properties.
      PubDate: 2017-11-14T06:00:25.739613-05:
      DOI: 10.1002/pola.28894
       
  • Imine-linked porous organic polymers showing mesoporous microspheres
           architectures with tunable surface roughness
    • Authors: Fan Song; He Zhang, De-Gao Wang, Tao Chen, Sheng Yang, Gui-Chao Kuang
      Abstract: Different kinds of porous organic polymers (POPs) bearing 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BDP) fluorophores have been developed to generate singlet oxygen upon light illumination. Herein, four imine-linked POPs were prepared by copolymerization of amine and aldehyde with different ratios of di-aldehyde A1 and A2. The POPs were investigated by a combination of techniques such as solid 13C NMR, FTIR, and nitrogen absorption–desorption isotherms and electronic microscopy. The results demonstrated that these POPs were prone to form hierarchical porous architectures. Scanning electron microscopy and transmission electron microscopy images revealed that the spherical morphologies showed different roughness, that is, BDP-POPs with more BDP aldehyde A2 presented rougher surface. Finally, these POPs were used to generate singlet oxygen (1O2) monitored by 1,3-diphenylisobenzofuran and bioimaging in HeLa cells. Our results indicated that the ability to generate 1O2 is dependent on the amount of BDP. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017Four porous organic polymers (BDP-POPs) with increasing molar ratios of BODIPY dyes were prepared. These porous materials showed microsphere morphologies with varying surface roughness and displayed different singlet oxygen generation abilities and fluorescent intensities in living cell. These properties were dependent on the BODIPY content in the polymers.
      PubDate: 2017-11-10T05:02:07.043317-05:
      DOI: 10.1002/pola.28902
       
  • Designing superhydrophobic surface based on fluoropolymer–silica
           nanocomposite via RAFT-mediated polymerization-induced self-assembly
    • Authors: Arindam Chakrabarty; Siva Ponnupandian, Nam-Goo Kang, Jimmy W. Mays, Nikhil K. Singha
      Abstract: Superhydrophobic surfaces (SHS) find versatile applications as coatings due to their very high water-repellency, self-cleaning, and anti-icing properties. This investigation describes the preparation of a SHS from surfactant-free hybrid fluoropolymer latex. In this case, reversible addition-fragmentation chain transfer (RAFT) polymerization was adopted to prepare a copolymer of 4-vinyl pyridine (4VP) and vinyl triethoxysilane (VTES), where the pyridine units were quaternized to make the copolymer soluble in water. The copolymer was further used as a macro-RAFT agent to polymerize 2,2,2-trifluoroethyl methacrylate (TFEMA) in a surfactant-free emulsion via polymerization-induced self-assembly (PISA). The macro-RAFT agent contained a small amount of VTES as co-monomer which was utilized to graft silica nanoparticles (SNPs) onto the P(TFEMA) spheres. The film prepared using the nanocomposite latex exhibited a nano-structured surface as observed by SEM and AFM analyses. Surface modification of the film with fluorinated trichlorosilane produced an SHS with a water contact angle (WCA) of 151.5°. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017Superhydrophobicity in polymers can be obtained by the incorporation of nanostructures to the surface. This study reveals an approach to achieve the same via the emulsion polymerization of fluoromonomer through polymerization-induced self-assembly (PISA), using a functional macro-RAFT agent followed by grafting of nanosilica. The macro-RAFT agent contained small amount of ethoxysilane functionalities that reacted with nanosilica to graft them around the fluoropolymer spheres. The resulting nano-structured polymer showed very high water contact angle (151.5°).
      PubDate: 2017-11-10T05:01:38.966838-05:
      DOI: 10.1002/pola.28883
       
  • Blocky poly(ɛ-caprolactone-co-butylene 2,5-furandicarboxylate)
           copolyesters via enzymatic ring opening polymerization
    • Authors: Juan Carlos Morales-Huerta; Antxon Martínez de Ilarduya, Sebastián Muñoz-Guerra
      Abstract: Cyclic oligo(butylene 2,5-furandicarboxylate) and ɛ-caprolactone were copolymerized in bulk at 130–150 °C by enzymatic ring opening polymerization using CALB as catalyst. Copolyesters within a wide range of compositions were thus synthesized with weight-average molecular weights between 20,000 and 50,000, the highest values being obtained for equimolar or nearly equimolar contents in the two components. The copolyesters consisted of a blocky distribution of the ɛ-oxycaproate (CL) and butylene furanoate (BF) units that could be further randomized by heating treatment. The thermal stability of these copolyesters was comparable to those of the parent homopolyesters (PBF and PCL), and they all showed crystallinity in more or less degree depending on composition. Their melting and glass-transition temperatures were ranging between those of PBF and PCL with values increasing almost linearly with the content in BF units. The ability of these copolyesters for crystallizing from the melt was evaluated by comparative isothermal crystallization and found to be favored by the presence of flexible ɛ-oxycaproate blocks. These copolyesters are essentially insensitive to hydrolysis in neutral aqueous medium but they became noticeably degraded by lipases in an extend that increased with the content in CL units. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017Blocky copolyesters made of ɛ-caprolactone and butylene furanoate with high molecular weights are obtained by enzymatic ring opening polymerization for a wide range of compositions. The PCL-PBF copolyesters are semicrystalline and biodegradable, and are free of metallic contaminants.
      PubDate: 2017-11-10T05:01:28.296338-05:
      DOI: 10.1002/pola.28895
       
  • Synthesis and fractionation of poly(phenylene methylene)
    • Authors: Andreas Braendle; Pascal Schwendimann, Markus Niederberger, Walter R. Caseri
      Abstract: Poly(phenylene methylene) (PPM) was isolated in a broad range of molar masses by optimization of the catalytic polymerization of benzyl chloride with SnCl4 or FeCl3, followed by fractionation by Soxhlet extraction or phase separation in concentrated solutions in poor solvents. Low molar mass products were also obtained by quenching the reaction at moderate monomer conversions. Products with number average molar masses (Mn) ranging from 200 to 61,000 g mol−1 were isolated, the latter being an order of magnitude above the previously reported values. DSC analysis of polymers of different molar masses revealed that the glass transition temperature follows the Flory-Fox equation reaching a plateau value of 65 °C at a molar mass between 10,000 and 20,000 g mol−1. The onset of decomposition temperature of higher molar mass products proceeds above 450 °C (maximum decomposition rate at 515 °C), according to TGA. Furthermore, the substitution pattern of PPM was discussed by study of chemical shifts of the methylene group (CH2) by extensive NMR spectroscopy (1H, 13C, DEPT, and HSQC) and by comparison with two mono-substituted derivatives of PPM—poly(2,4,6-trimethylphenylene methylene) and poly(2,3,5,6-tetramethylphenylene methylene)—which were synthesized analogous to PPM. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017High molar mass poly(phenylene methylene) (Mn up to 60,000 g mol–1) was achieved by an optimized polymerization of benzyl chloride with SnCl4 or FeCl3 as a catalyst, followed by subsequent fractionation of the polymer. End group analysis by NMR spectroscopy revealed that the polymerization proceeds via a step growth mechanism. This first isolation of high molar mass PPM facilitates the search of potential applications of PPM.
      PubDate: 2017-11-10T05:00:29.512766-05:
      DOI: 10.1002/pola.28900
       
  • Dendritic poly(benzyl ether)-b-poly(N-vinylcaprolactam) block copolymers:
           Self-organization in aqueous media, thermoresponsiveness and
           biocompatibility
    • Authors: Gang Tang; Minqi Hu, Fuxi He, Dan You, Yangyang Qian, Yunmei Bi
      Abstract: Four generations of new amphiphilic thermoresponsive linear-dendritic block copolymers (LDBCs) with a linear poly(N-vinylcaprolactam) (PNVCL) block and a dendritic poly(benzyl ether) block are synthesized by atom transfer radical polymerization (ATRP) of N-vinylcaprolactam (NVCL) using dendritic poly(benzyl ether) chlorides as initiators. The copolymers have been characterized by 1H NMR, FTIR, and GPC showing controlled molecular weight and narrow molecular weight distribution (PDI ≤ 1.25). Their self-organization in aqueous media and thermoresponsive property are highly dependent on the generation of dendritic poly(benzyl ether) block. It is observed for the LDBCs that the self-assembled morphology changes from irregularly spherical micelles, vesicles, rod-like large compound vesicles (LCVs), to the coexistence of spherical micelles and rod-like LCVs, as the generation of the dendritic poly(benzyl ether) increases. The results of a cytotoxicity study using an MTT assay method with L929 cells show that the LDBCs are biocompatible. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017Novel amphiphilic thermoresponsive linear-dendritic block copolymers composed of a linear poly(N-vinylcaprolactam) (PNVCL) chain and the first to the fourth generations of a Fréchet-type polyether have been synthesized. Their self-assembly behavior and thermoresponsive property are affected by the generation of the dendritic poly(benzyl ethers) block. They are proven to be nontoxic to L929 cells.
      PubDate: 2017-11-02T22:35:53.444754-05:
      DOI: 10.1002/pola.28897
       
  • Hydrogen bonding improved atom transfer radical polymerization of methyl
           methacrylate with a glycerol/1,3-dimethyl-2-imidazolidinone green system
    • Authors: Mengying Tian; Jirong Wang, Jun Zhou, Jianyu Han, Feipeng Du, Zhigang Xue
      Abstract: 1,3-Dimethyl-2-imidazolidinone (DMI) was used as an efficient media in iron-catalyzed atom transfer radical polymerizations (ATRPs) and AGET ATRPs of MMA. Both of these systems presented relatively high reaction rate and well controllability even in the presence of limited amount of DMI. In iron-catalyzed AGET ATRPs, a variety of alcohols were served as reducing agents and all the polymerizations behaved excellent activity features, especially for glycerol. The hydrogen-bond interaction between DMI and glycerol was also studied, which may release the reducing ability of glycerol by decreasing the viscosity of glycerol similar to deep eutectic solvents (DESs). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017This article reports the iron-catalyzed “green” ATRP with DMI as ligand, and the hydrogen-bond interaction between DMI and glycerol was also detailedly studied, which increase the polymerization rate and controllability of the whole reaction process.
      PubDate: 2017-10-27T23:05:58.438158-05:
      DOI: 10.1002/pola.28893
       
  • Conjugated polymers based on 1,8-naphthalene monoimide with high electron
           mobility
    • Authors: Guomin Zhu; Youdi Zhang, Yu Hu, Xiaohong Zhao, Zhongyi Yuan, Yiwang Chen
      Abstract: 1,4,8,9-Naphthalene diimides (NDIs) with strong electron accepting ability and high stability are excellent building blocks for semiconductor polymers. However, 1,8-naphthalene monoimide (NMI) with similar structure and energy levels as that of NDI has never been used to construct conjugated polymers because of synthetic difficulty. Herein, 3,6-dibromo-NMI (DBNMI) with bulky alkyl groups was obtained effectively in a four-step synthesis, and three donor-acceptor (D-A) type conjugated polymers based on NMI were firstly prepared. These polymers have strong absorption in the range of 300–600 nm, low LUMO level of 3.68 eV, and moderate bandgaps of 2.18 eV. Space charge limiting current measurements indicate these polymers are typical electron transporting materials, and the highest electron mobility is up to 5.8 × 10−3 cm2 V−1 s−1, which is close to the star acceptor based on NDI (N2200, 5.0 × 10−3 cm2 V−1 s−1). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 20173,6-Dibromo-NMI with bulky alkyl groups was obtained effectively in a four-step synthesis, and three donor-acceptor (D-A) type conjugated polymers based on NMI were prepared. SCLC measurements indicate that these polymers are typical electron transporting materials, and that the highest electron mobility is up to 5.8 × 10−3 cm2 V−1 s−1. This is close to the star acceptor based on NDI (N2200, 5.0 × 10−3 cm2 V−1 s−1).
      PubDate: 2017-10-27T23:05:51.089195-05:
      DOI: 10.1002/pola.28891
       
  • Issue Information - Cover Description
    • Pages: 155 - 161
      PubDate: 2017-12-02T07:22:05.422294-05:
      DOI: 10.1002/pola.28789
       
  • Synthesis and thermoresponsive properties of OEGylated polypeptide with a
           LCST at body temperature in water and with a UCST in alcohol or
           ethanol/water solvent mixture
    • Authors: Chenglong Ge; Wenjun Liu, Ying Ling, Haoyu Tang
      Pages: 163 - 173
      Abstract: Thermoresponsive polypeptides bearing oligo(ethylene glycol) (OEG) pendants (i.e., P1-OEGx and P2-OEGx, x = 3, 7) were synthesized by copper-mediated 1,3-dipolar cycloaddition with high grafting efficiency (≥97%) between side-chain “clickable” polypeptides, namely poly(γ-4-(propargoxycarbonyl)benzyl-l-glutamate) (P1) or poly(γ-4-(4-propargoxyphenoxycarbonyl)benzyl-l-glutamate) (P2) and azido functionalized OEG (N3-OEGx). P1 and P2 with similar degree of polymerization (DP = 35 or 37) were prepared from triethylamine initiated ring-opening polymerization of respective N-carboxyanhydrides. P1-OEGx (x = 3, 7) and P2-OEG7 showed reversible UCST-type phase transitions in various alcoholic solvents (e.g., ethanol, propanol, n-butanol, and n-pentanol). P2-OEG3 also showed reversible UCST-type phase transitions in ethanol/water solvent mixtures at the weight percentage of ethanol no less than 50 wt %. P1-OEG7 and P2-OEG7 showed reversible LCST-type phase transitions in aqueous solutions. Variable-temperature UV–vis spectroscopy revealed that the LCST-type phase transition temperature (Tpt) of P2-OEG7 with benzoic acid phenyl ester linkages was at around body temperature and it was barely changed with the variation of polymer concentration, yet it showed noticeable dependence on the nature of salt (i.e., NaCl, NaBr, NaI, or KCl) and salt concentration in the range of 0–300 mM. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 163–173A new homopolypeptide with LCST-type phase transition temperature (Tpt) at body temperature was synthesized and characterized. It also showed reversible UCST-type phase behaviors in various alcohols and ethanol/water solvent mixtures.
      PubDate: 2017-10-26T20:42:31.703331-05:
      DOI: 10.1002/pola.28868
       
  • Uni-molecular nanoparticles of poly(2-oxazoline) showing tunable
           thermoresponsive behaviors
    • Authors: Yuehuan Chu; Huaan Li, Huahua Huang, Houbo Zhou, Yi Chen, Böckler Andreas, Lixin Liu, Yongming Chen
      Pages: 174 - 183
      Abstract: Herein, cylindrical molecular bottlebrushes grafted with poly(2-oxazoline) (POx) as a shaped tunable uni-molecular nanoparticle were synthesized via the grafting-onto approach. First, poly(glycidyl methacrylate) (PGMA) backbones with azide pendant units were prepared via reversible addition fragmentation transfer (RAFT) polymerization followed by post-modification. The degree of polymerization (DP) of the backbones was tuned in a range from 20 to 800. Alkynyl-terminated POx side chains were synthesized by living cationic ring opening polymerization (LCROP) of 2-ethyl-2-oxazoline (EtOx) and 2-methyl-2-oxazoline (MeOx), respectively. The DP of side chains was varied between 20 and 100. Then, the copper-catalyzed azide-alkynyl cycloaddition (CuAAC) click chemistry was conducted with a feed ratio of [alkynyl]:[azide] = 1.2:1 to yield a series of brushes. Depending on the DP of side chains, the grafting density ranged between 47 and 85%. The resulting brushlike nanoparticles exhibited shapes of sphere, rod and worm. Aqueous solutions of PEtOx brushes demonstrated a thermoresponsive behavior as a function of the length of backbones and side chains. Surprisingly, it was found that the lower critical solution temperature of PEtOx brushes increased with a length increase of backbones. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 174–183Cylindrical bottlebrushes grafted with poly(2-oxazoline) as a shape tunable uni-molecular nanoparticle were synthesized via the grafting-onto approach. The resulting bottlebrushes exhibited different shapes including spherical, rod and worm, mainly depending on the length of their backbones. Furthermore, the lower critical solution temperature of thermoresponsive bottlebrushes with poly(2-ethyl-2-oxazoline) as side chain increased with increasing the hydrophobic backbone length.
      PubDate: 2017-10-30T04:03:58.708385-05:
      DOI: 10.1002/pola.28889
       
  • Strategy for rational control of stereosequence in free radical
           polymerization of acrylates
    • Authors: Hitoshi Tanaka; Kazuyoshi Maki, Yoshitaka Matsubara
      Pages: 184 - 193
      Abstract: Radical polymerization of cyclic analogs of acrylates, (S)- and (R)-2-isopropyl-5-methylene-1,3-dioxolan-4-ones (1S and 1R), successfully afforded a functional polymer having the tacticity continuously controlled from 29% to ∼100% of meso triad (mm) over a wide range of temperature only by changing the molar ratio of 1S/1R in feed. Plot of the number fractions of the triad versus diad of poly(1) was in good agreement with the Bernoulli statistics. In the polymerization in chiral solvents having analogs structure of the monomers, the tacticity and specific rotation of the resulting polymer were specifically varied depending on the structure and concentration of the solvents. Model propagation reaction at dimeric radical calculated with density functional theory reproduced a methodical induction of the chirality to the main chain from the branched chiral monomeric unit, which supports the experimental expectations. It is remarkable that the ceiling temperature of 1 is tremendously high, for example, 193 °C in [1 (ee = 72.6%)] = 0.05 mol/L, and the isospecific polymerization is maintained even at such a high temperature, which enabled the control of polymer tacticity over a wide range of temperature. The mechanism of the stereosequence in radical polymerization was discussed experimentally and theoretically. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 184–193Arbitrary control of polymer isotacticity has been successfully achieved for the first time by changing a monomer composition in radical polymerization of renewable lactic acid-derived methylene dioxolanones over a wide range of temperatures. An achievement of the continuous isotacticity control by radical polymerization in this work is important and valuable progress to the facile control of tacticity in vinyl polymerization, providing a clue to understanding the stereochemistry in vinyl polymerization, in particular of the α,β-unsaturated carbonyl compounds including (meth)acrylates, vinyl ketones, and acrylamides.
      PubDate: 2017-11-06T09:20:30.903192-05:
      DOI: 10.1002/pola.28878
       
  • Structural diversity in poly(disulfide)s
    • Authors: Raju Bej; Jayita Sarkar, Suhrit Ghosh
      Pages: 194 - 202
      Abstract: This article reports a synthetic methodology for single step preparation of telechelic poly(disulfide)s (PDS) by step-growth polymerization between a di-thiol and a commercially available monomer 2,2′-dithiodipyridine in presence of a functional group appended pyridyl disulfide moiety as the “mono-functional impurity” (MFI). Redox-destructible well-defined segmented PDSs with functional chain terminal, predicted and tunable degree of polymerization and narrow polydispersity index (
      PubDate: 2017-10-15T05:11:21.228017-05:
      DOI: 10.1002/pola.28882
       
  • Synthesis of lactide/ɛ-caprolactone quasi-random copolymer by using
           rationally designed mononuclear aluminum complexes with modified
           β-ketiminato ligand
    • Authors: Hai-Chao Huang; Zong-Jun Li, Bin Wang, Xiaolu Chen, Yue-Sheng Li
      Pages: 203 - 212
      Abstract: A series of novel aluminum complexes containing bulky aryl-β-ketiminato ligands [ArNCHC10H7C6H5O]Al(CH3)2 (3a, Ar = C6F5; 3b, Ar = C6H5; 3c, Ar = 2,6-iPr2C6H3) have been synthesized in high yields. These complexes were identified by 1H and 13C NMR spectroscopy, elemental analysis, and X-ray structural analysis. All the aluminum complexes could efficiently catalyze the ROP of ɛ-caprolactone (ɛ-CL) and Lactide (LA) in a controlled manner. It was found that the steric effect of the ligand has less effect on the ROP of CL, while the polymerization rate of L-LA was suppressed significantly. More interestingly, this kind of catalysts can promote the random copolymerization of ɛ-CL and L-LA. The transesterification side reaction and the polymer composition could be adjusted by modulating the electronic and steric effects of the ligand. In paticular, compound 3c could produce quasi-random copolymers without transesterification side reactions, as indicated by both the values of the reactivity ratios of the two monomers (rLA = 1.31; rCL = 0.99) and the similar average lengths of the caproyl and lactidyl sequences (LCL = 2.34; LLA = 2.44). Finally, a drug-random copolymer conjugates could be easily prepared by using 3c, indicating a potential application of 3c in pharmacutical and biomedical field. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 203–212A series of novel aluminum complexes containing bulky aryl-β-ketiminato ligands have been synthesized. The bulky steric hindrance could narrow the gap between the reactivity of the ɛ-caprolactone and lactide in the copolymerization, affording quasi-random copolyester without transesterification.
      PubDate: 2017-10-16T01:25:35.063355-05:
      DOI: 10.1002/pola.28886
       
  • Bay-annulated indigo based near-infrared sensitive polymer for organic
           solar cells
    • Authors: Jingshuai Zhu; Tengfei Li, Keli Shi, Jiayu Wang, Yuze Lin, Gui Yu, Xiaowei Zhan
      Pages: 213 - 220
      Abstract: A new conjugated polymer (PBAIIDTT) based on bay-annulated indigo and indacenodithieno[3,2-b]thiophene was designed, synthesized, and characterized. PBAIIDTT shows strong absorption in 400–500 and 600–800 nm, and its HOMO and LUMO energy levels are −5.45 eV and −3.65 eV, respectively. In organic field-effect transistors, the polymer exhibits a relatively high hole mobility of 0.39 cm2 V−1 s−1. PBAIIDTT was added to poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PC61BM) based organic solar cells. Ternary blend solar cells with 10% PBAIIDTT show an increased short circuit current density due to the broadened photocurrent generated in the near-infrared region, and a power conversion efficiency of 3.78%, which is higher than that of the P3HT:PC61BM binary control devices (3.33%). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 213–220A new conjugated polymer (PBAIIDTT) based on bay-annulated indigo and indacenodithieno[3,2-b]thiophene was designed, synthesized, and characterized. PBAIIDTT exhibits a hole mobility of 0.39 cm2 V−1 s−1 in field-effect transistors. Organic solar cells based on a P3HT:PC61BM:PBAIIDTT ternary blend show efficiency of 3.78%, which is higher than that of the P3HT:PC61BM binary control devices (3.33%).
      PubDate: 2017-11-04T07:26:03.564517-05:
      DOI: 10.1002/pola.28887
       
  • Determination of ceiling temperature and thermodynamic properties of low
           ceiling temperature polyaldehydes
    • Authors: Jared M. Schwartz; Anthony Engler, Oluwadamilola Phillips, Jihyun Lee, Paul A. Kohl
      Pages: 221 - 228
      Abstract: Knowledge of the ceiling temperature and thermodynamic variables for low ceiling temperature polymers is critical to understanding the material's synthesis and use. Synthesis of the polymer below its ceiling temperature is the routine polymerization route. In situ 1H NMR of the equilibrium polymerization reaction can provide critical information for determining the enthalpy and entropy of polymer formation. Three polyaldehydes were synthesized with in situ 1H NMR, and their energies of formation were determined for the linear region of ceiling temperature. Insights into the mechanism of polymerization were also found using this method. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 221–228The polymerization of a low ceiling temperature polymer is typically performed below its ceiling temperature. Determining the ceiling temperature can be difficult. Three polyaldehydes were synthesized by a 1H in situ NMR method to determine the enthalpies and entropies of formation as well as the ceiling temperatures. Unique insights into the polymerization mechanisms were also observed.
      PubDate: 2017-10-27T23:06:28.57712-05:0
      DOI: 10.1002/pola.28888
       
  • Visible light-induced RAFT polymerization of methacrylates with
           benzaldehyde derivatives as organophotoredox catalysts
    • Authors: Qian Yang; Xianhong Zhang, Wenchao Ma, Yuhong Ma, Dong Chen, Li Wang, Changwen Zhao, Wantai Yang
      Pages: 229 - 236
      Abstract: The benzaldehyde derivatives, such as 2,4-dimethoxy benzaldehyde (PC1) and p-anisaldehyde (PC2), were successfully used as photoredox catalysts (PCs) in combination with typical RAFT agent 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CTP) for the controlled photoinduced electron transfer RAFT polymerization (PET-RAFT) of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) at room temperature. The kinetics of the polymerizations showed first order with respect to monomer conversions. Besides, the average number molecular weights (Mn) of the produced polymers increased linearly with the monomer conversions and kept relatively narrow polydispersity (PDI = Mw/Mn). For example, the Mn of PMMA increased from about 3400 to 17,300 g mol−1 with the increasing in monomer conversion from 11% to 85%, and the PDI maintained around 1.36. The living features of polymerizations with the PC1 and PC2 as catalysts have also been further supported by chain extension and synthesis of PMMA-b-PBnMA diblock copolymer. As a result, the simplicity and efficiency of benzaldehyde derivatives catalyzed PET-RAFT polymerization have been demonstrated under mild conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 229–236The benzaldehyde derivatives used as photoredox catalysts (PCs) in combination with typical RAFT agent 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CTP) for the controlled PET-RAFT of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) at room temperature was achieved successfully. The Mn of the produced polymers increased linearly with the monomer conversions and the polydispersity kept relatively narrow. Furthermore, PMMA-b-PMMA and PMMA-b-PBnMA block copolymer were synthesized by employing macro-PMMA as macro-RAFT agent.
      PubDate: 2017-10-27T23:05:46.66645-05:0
      DOI: 10.1002/pola.28890
       
  • A dismantlable photoadhesion system fabricated by an anionic UV curing of
           epoxy resins with a base amplifier having a disulfide bond
    • Authors: Masahiro Furutani; Ayaru Kakinuma, Koji Arimitsu
      Pages: 237 - 241
      Abstract: A base amplifier (BA) that autocatalytically generates a diamine having a disulfide bond has been developed. Diamines generated from this BA are integrated into cross-linked networks of epoxy resins that also have disulfide bonds. Anionic UV curing is performed using a photobase generator, the BA and the epoxy resins, and cured films are obtained after UV irradiation and subsequent heating at 160 °C. Furthermore, this curing system is applied successfully to adhesion of two stainless substrates, which is cancelled with gentle heating and a shear force. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 237–241A base amplifier (BA) that generates a diamine having a disulfide bond has been developed. Anionic UV curing of epoxy resins is performed using this BA, leading to photoadhesion and subsequent thermal dismantlement.
      PubDate: 2017-11-11T07:18:16.139566-05:
      DOI: 10.1002/pola.28898
       
  • Optoeletronic properties of poly(N-alkenyl-carbazole)s driven by polymer
           stereoregularity
    • Authors: Antonio Botta; Chiara Costabile, Vincenzo Venditto, Stefania Pragliola, Rosalba Liguori, Alfredo Rubino, Domenico Alberga, Marika Savarese, Carlo Adamo
      Pages: 242 - 251
      Abstract: Stereoregular polymers like isotactic poly(N-butenyl-carbazole) (i-PBK), isotactic and syndiotactic poly(N-pentenyl-carbazole) (i-PPK and s-PPK), and poly(N-hexenyl-carbazole) (i-PHK and s-PHK) are synthesized using the stereospecific homogeneous “single site” Ziegler-Natta (Z-N) catalysts: rac-dimethylsilylbis(1-indenyl)zirconium dichloride (1)/methylaluminoxane (MAO) and diphenylmethylidene(cyclopentadienyl)-(9-fluorenyl)zirconium dichloride (2)/MAO. Catalytic activity is rationalized by density functional theory (DFT) calculations. All synthesized polymers are fully characterized by NMR, thermal, wide-angle X-ray diffraction, and fourier transform infrared spectroscopy analysis. Fluorescence measurements on isotactic and syndiotactic polymer films indicate that all polymers give rise to excimers, both “sandwich-like” and “partially overlapping.” Excimer formation is essentially driven by the polymer tacticity. Isotactic polymers generate both sandwich-like and partially overlapping excimers, while syndiotactic polymers give rise especially to partially overlapping ones. A theoretical combined molecular dynamics–time dependent DFT approach is also used to support the experimental results. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 242–251Stereoregular poly(N-alkenyl-carbazole)s were synthesized using homogeneous “single site” Ziegler-Natta (Z-N) catalysts. Polymer microstructures and chemical-physical properties were also investigated. The photoluminescence behaviors of the different polymer stereoisomers were compared, and the experimental results were rationalized by molecular dynamics–time dependent DFT calculations. Both experimental and theoretical results indicate that polymer tacticity strongly influences optical properties.
      PubDate: 2017-11-04T07:25:44.078138-05:
      DOI: 10.1002/pola.28899
       
 
 
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