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Journal Cover Polymer
  [SJR: 1.188]   [H-I: 197]   [162 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0032-3861
   Published by Elsevier Homepage  [3089 journals]
  • In-situ pore filling of TiO2 nanoparticles in honeycomb patterned porous
           films: A modified breath figure method
    • Authors: Bo Kyoung Shin; Umashankar Male; Do Sung Huh
      Pages: 1 - 8
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Bo Kyoung Shin, Umashankar Male, Do Sung Huh
      Polystyrene (PS) honeycomb patterned porous films filled with titanium dioxide (TiO2) nanoparticles were prepared by a modified breath figure method. The honeycomb patterned porous films filled with TiO2 nanoparticles were obtained by pouring titanium butoxide over partially dried PS solution during the fabrication of the PS films under humid conditions. TiO2 nanoparticles were obtained by the hydrolysis of titanium butoxide in the condensed micro water droplets at the PS solution/air interface. Morphology, elemental mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and UV−Visible analysis support the formation of TiO2 nanoparticles in the honeycomb patterned pores. XRD studies showed that the formed TiO2 nanoparticles are anatase. Photo-activity of the incorporated TiO2 nanoparticles was examined by the change of the water contact angle of the films before and after UV irradiation. Water contact angles was decreased by UV irradiation, implying the transformation of the surface from hydrophobic to hydrophilic due to the photo-induced wettability by TiO2.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.011
      Issue No: Vol. 135 (2017)
       
  • Tadpole-shaped magnetic block copolymer: Self-assembly induced increase of
           magnetic susceptibility
    • Authors: Tongzhou Zhang; Xiaoliang Yu; Xiaoyan Yuan; Yunhui Zhao; Lixia Ren
      Pages: 9 - 15
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Tongzhou Zhang, Xiaoliang Yu, Xiaoyan Yuan, Yunhui Zhao, Lixia Ren
      Self-assembly induced increase of magnetic susceptibility for the tadpole-shaped block copolymer based on paramagnetic FeCl4 pyridinium was reported in this work. The tadpole-shaped block copolymer was prepared by sequential reversible addition-fragmentation chain transfer polymerization of styrene (St) and 4-vinylpyridine (4VP) at the presence of chain transfer agent-modified polyhedral oligomeric silsesquioxanes (POSS). The corresponding magnetic block copolymer (POSS-PSt-b-QP4VP(FeCl4)) was obtained by quternization of 4VP and complexation with FeCl3. The prepared block copolymer was paramagnetic with magnetic susceptibility of 15.4 × 10−6 emu g−1, as investigated by superconducting quantum interference device. Surprisingly, the magnetic susceptibility of the block copolymer was almost doubled (27.5 × 10−6 emu g−1) after self-assembly in thin film. Since the composition of the block copolymer is unchanged, the increase of the susceptibility should be generated by the self-assembly, which makes the magnetic FeCl4 − more ordered. And, self-assembly will be an efficient and convenient method in improving magnetic properties of such polymers.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.009
      Issue No: Vol. 135 (2017)
       
  • A novel design strategy for triple-network structure hydrogels with
           high-strength, tough and self-healing properties
    • Authors: Yixi Wang; Jingye Niu; Juan Hou; Zhicun Wang; Jianning Wu; Guihua Meng; Zhiyong Liu; Xuhong Guo
      Pages: 16 - 24
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Yixi Wang, Jingye Niu, Juan Hou, Zhicun Wang, Jianning Wu, Guihua Meng, Zhiyong Liu, Xuhong Guo
      In this study, we prepared a novel triple-network (TN) structure hydrogel composed of polyacrylic acid (PAA), agar and polyvinyl alcohol (PVA). The obtained TN hydrogel has a superior mechanical property as well as self-healing property feature. In the TN hydrogel system, PAA-Fe3+ polymer mainly providing hydrogel self-healing properties by the ionic coordinates between COO− and Fe3+ as the first network, while, agar and PVA polymers gel mainly providing hydrogel high mechanical properties as the second and third network. The structure of TN the hydrogel can be controlled by adjusting the content of Fe3+ and composition in the three polymers. When 1.5 wt% Fe3+ in the TN hydrogels, the PAA/Agar/PVA TN hydrogels possess high mechanical strength, the fracture strain and fracture stress were 497% and 450 kPa, respectively, and the compression strength reached up to 1337 kPa under the compression deformation of 80%. Besides, the TN hydrogels exhibited excellent self-healing ability, when healed 72% at tensile stress and 84% at tensile strain after 24 h without adding any solvent or additive. The research offers a novel design strategy to improve mechanical strength and self-healing ability of hydrogels by controlling the compositions and interactions in the three networks.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.076
      Issue No: Vol. 135 (2017)
       
  • Phase-selectively soluble, polymer-supported salen catalyst prepared using
           atom transfer radical polymerization (ATRP)
    • Authors: Yue Liu; Christopher E. Hobbs
      Pages: 25 - 29
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Yue Liu, Christopher E. Hobbs
      This communication describes the use of atom transfer radical polymerization (ATRP) to prepare a new phase-selectively soluble, polymer-supported CrIII salen catalyst. This catalyst was used to facilitate the asymmetric ring opening of cyclohexene oxide and could be recovered and reused up to 5 times using liquid/liquid separation techniques.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.001
      Issue No: Vol. 135 (2017)
       
  • Toughening brittle polymers with shape memory polymers
    • Authors: Giuliano Siniscalchi Martins; Iaci Miranda Pereira; Rodrigo Lambert Oréfice
      Pages: 30 - 38
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Giuliano Siniscalchi Martins, Iaci Miranda Pereira, Rodrigo Lambert Oréfice
      Polystyrene (PS) was blended with shape memory polyurethanes (SMPU). Styrene blocks were grafted onto PU chains during SMPU synthesis to yield a modified SMPU with a higher affinity towards PS. Furthermore, blends containing a compatibilizer, poly (styrene-co-maleic anhydride) (SMA), were also prepared by melt mixing the components. The non-compatibilized blends display phase separated structures with PS rich and SMPU rich phases, which were less evident in blends prepared with either the modified SMPU or SMA compatibilizer. The elastic storage modulus of PS was less affected when blended with SMPU in samples containing modified SMPU with styrene grafts. The impact strength of the blends with higher contents of SMPU modified with styrene blocks (25 and 50 wt.%), after shape recovery, was higher than the impact strength of neat PS. The incorporation of shape memory polymers into a brittle polymer matrix is a potential strategy to improve the toughness by external stimuli.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.017
      Issue No: Vol. 135 (2017)
       
  • Positronium probes free volume to identify para- and meta-aramid fibers
           and correlation with mechanical strength
    • Authors: R. Ramani; T.M. Kotresh; R. Indu Shekar; F. Sanal; U.K. Singh; R. Renjith; G. Amarendra
      Pages: 39 - 49
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): R. Ramani, T.M. Kotresh, R. Indu Shekar, F. Sanal, U.K. Singh, R. Renjith, G. Amarendra
      We adopt here a novel approach to identify the para- and meta-aramid fibers using the available free volume in them. Positron Annihilation Lifetime Spectroscopy (PALS) has been employed to characterize the free volume in these fibers. The free volume content in the para-variety (Kevlar) is less and the free volume distribution is narrow as compared to its meta-counterpart (Nomex). The results are further validated by characterizing the free volume content in Nomex IIIA fibers, which is a blend composed mainly of para- and meta-aramid fibers. The free volume results are in good correlation with the mechanical properties of these fibers obtained by Universal Testing Machine (UTM), structural studies by X-ray diffraction (XRD) and storage modulus using Dynamic Mechanical Thermal Analysis (DMTA). The thermal decomposition temperature (Td) of the fibers is characterized by thermo gravimetric analysis (TGA). We also show here the first results of an appreciable glass transition temperature (Tg) not only for the Nomex fibers but also for its blend Nomex IIIA using the combined results of Differential Scanning Calorimetry (DSC) and DMTA.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.064
      Issue No: Vol. 135 (2017)
       
  • A novel approach for measuring room temperature enthalpy of mixing and
           associated solubility estimation of a drug in a polymer matrix
    • Authors: Jonas Alin; Nico Setiawan; Matthew Defrese; James DiNunzio; Hang Lau; Lisa Lupton; Hanmi Xi; Yongchao Su; Haichen Nie; Nathan Hesse; Lynne S. Taylor; Patrick Jules Marsac
      Pages: 50 - 60
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Jonas Alin, Nico Setiawan, Matthew Defrese, James DiNunzio, Hang Lau, Lisa Lupton, Hanmi Xi, Yongchao Su, Haichen Nie, Nathan Hesse, Lynne S. Taylor, Patrick Jules Marsac
      The utility of amorphization of drug molecules, such as enhanced solubility, dissolution rate and oral bioavailability, has been well exemplified in the literature. Yet, the application of this technique is often hindered by the crystallization liability of the drug. Amorphous solid dispersions (ASD), in which polymers are mixed with the amorphous drug, are often utilized to maintain the amorphous form. Several approaches have been illustrated in the literature to quantify the degree of mixing of drug and polymer. Although successful quantification has been demonstrated, all of these approaches probe the mixing energies at temperatures close to the melting temperature and, thus, require an extrapolation to room/storage temperature. Hence, an approach to directly estimate the drug-polymer extent of mixing at room temperature would enable a more accurate prediction of the physical stabilities. Herein, solution calorimetry was used to determine enthalpies of mixing of drug and polymer dispersions. These are necessary for the estimation of the Flory-Huggins interaction parameter, and associated free energy of mixing function. The estimated free energy of mixing, in turn, enabled the calculation of the drug solubility in the polymer system, which is a critical thermodynamic parameter in predicting the physical stability of an ASD.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.056
      Issue No: Vol. 135 (2017)
       
  • Bio-derived cellulose nanofibril reinforced
           poly(N-isopropylacrylamide)-g-guar gum nanocomposite: An avant-garde
           biomaterial as a transdermal membrane
    • Authors: Koushik Dutta; Beauty Das; Jonathan Tersur Orasugh; Dipankar Mondal; Arpita Adhikari; Dipak Rana; Rajdeb Banerjee; Roshnara Mishra; Sumit Kar; Dipankar Chattopadhyay
      Pages: 85 - 102
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Koushik Dutta, Beauty Das, Jonathan Tersur Orasugh, Dipankar Mondal, Arpita Adhikari, Dipak Rana, Rajdeb Banerjee, Roshnara Mishra, Sumit Kar, Dipankar Chattopadhyay
      The delivery of diltiazem hydrochloride in therapeutical doses has attracted an immense research interest. However, its slower penetration through the transdermal route has stipulated to develop a competent transdermal membrane. Therefore, a nanocomposite based patch was formulated by exploring co-polymer and jute derived nano-cellulose. Poly(N-isopropylacrylamide) was grafted into guar gum (GG-g-PNIPAAm) with different feeding ratios. The co-polymer formation was authenticated by FTIR and 13C NMR spectra. The nanocomposite were prepared by incorporating nanofibre (0.5–2 wt%) into GG-g-PNIPAAm. The structural and morphological studies supported good interactions and presence of nano-cellulose on co-polymer. GG-g-PNIPAAm has showed higher thermostability than guar gum. Moreover, the addition of CNF has improved the thermo-mechanical and barrier properties of the nanocomposite. The nanocomposite containing 1 wt% CNF was found to be best performing. The patch showed in-vitro cyto-compatibility and non-irritant behaviour. The in-vitro release study of best nanocomposite revealed controlled drug release capability with 7.78 and 22.9% after 5 and 20 h, respectively.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.015
      Issue No: Vol. 135 (2017)
       
  • Thermal effects on the strain-induced β to α form crystalline structural
           transition of solid-state syndiotactic polystyrene
    • Authors: Fuyuaki Endo; Atsushi Hotta
      Pages: 103 - 110
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Fuyuaki Endo, Atsushi Hotta
      Thermal effects on the strain-induced structural transition from β-form to α-form crystals of syndiotactic polystyrene (sPS) were investigated by changing the stretching temperature and the annealing temperature. When sPS was stretched at lower temperature (near the glass transition temperature (T g) of sPS (∼130 °C)), the crystalline structural transition was incomplete, producing fragmented β-form and mesomorphic α-form crystals. Stretching at higher temperature facilitated the crystalline structural transition from β to α. For the sPS specimen stretched at 130 °C, the β-form crystals broke into small pieces, simultaneously creating mesomorphic α-form crystals. After annealing, the fragmented β-form crystals and the mesomorphic α-form crystals were reorganized to become complete crystals. The reorganization became more pronounced as the annealing temperature increased. The main role of the mechanical strain and the heat, therefore, could be the destruction of β-form crystals to produce fragmented β-form crystals and mesomorphic α-form crystals, and the formation of complete crystals, respectively.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.013
      Issue No: Vol. 135 (2017)
       
  • Solution-grown crystals of precise acid- and ion-containing polyethylenes
    • Authors: Lu Yan; Karen C. Bustillo; Ouliana Panova; Andrew M. Minor; Karen I. Winey
      Pages: 111 - 119
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Lu Yan, Karen C. Bustillo, Ouliana Panova, Andrew M. Minor, Karen I. Winey
      Crystals of precise acid- and ion-containing polyethylenes were prepared from solution. While large pendant groups on polyethylene backbones are typically excluded from the crystalline domain, the precisely-placed acid and ionic functional groups are accommodated into the solution-grown crystals. Polyethylene containing carboxylic acid pendant groups on every 21st carbon atom (p21AA) grows into rectangular shaped crystals with an average thickness of 9 nm, which is 3–4 times the all-trans chain length between the functional groups. This thickness indicates that the carboxylic acid groups are incorporated within the crystals. Electron diffraction images and Raman spectra indicate that p21AA backbones are hexagonally packed with more gauche chain conformations than the polyethylene orthorhombic phase. The precise polyethylene containing geminal carboxylic acid groups placed every 21 carbon atoms (p21gAA) forms irregular-shaped crystals with an average thickness 8 nm. Similar to p21AA, p21gAA incorporates the geminal acid groups into its solution-grown crystals. Surprisingly, the polymer with imidazolium bromide groups on every 21st carbon (p21ImBr) produces remarkably large crystals with thicknesses of 200–900 nm, and widths of 6–12 μm. Finally, we propose a multi-layer stack of adjacent reentry structures that is consistent with the incorporation of large functional groups into the solution-growth crystals of these precise polyethylenes. Interestingly, this stacked structure is distinct from our recent results in melt-crystallized p21AA, where the layers are nearly transverse to the lamellae.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.007
      Issue No: Vol. 135 (2017)
       
  • Copolyesters based on bibenzoic acids
    • Authors: H. Eliot Edling; Haoyu Liu; Hua Sun; Ryan J. Mondschein; David A. Schiraldi; Timothy E. Long; S. Richard Turner
      Pages: 120 - 130
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): H. Eliot Edling, Haoyu Liu, Hua Sun, Ryan J. Mondschein, David A. Schiraldi, Timothy E. Long, S. Richard Turner
      Novel copolyester thermoplastics based on 4,4′-bibenzoate and 3,4′-bibenzoate moieties with ethylene glycol were synthesized via melt polycondensations. Crystallization behavior was modified by the additional incorporation of terephthalate or isophthalate units into the backbones. Copolyester compositions were verified by 1H NMR spectroscopy and molecular weights were assessed using inherent viscosity (η inh ). Thermogravimetric analysis (TGA) showed single-step weight losses in the range of 360–400 °C. Differential scanning calorimetry (DSC) was used to determine melting points and glass transition temperatures over a wide range of copolyester compositions. Observation of thermal data was used to identify amorphous windows in composition ranges containing 3,4′BB and 4,4′BB moieties. Dynamic mechanical analysis (DMA) provided information about thermal transitions and sub-T g relaxations. Mechanical data were obtained using tensile testing to expand structure-property- morphology relationships. Permeability analysis helped to understand how monomer symmetry affects oxygen diffusivity and solubility in selected amorphous film and biaxially oriented copolyester samples.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.004
      Issue No: Vol. 135 (2017)
       
  • Influence of substituted structure of Percec-type mini-dendritic end
           groups on aggregation and rheology of hydrophobically modified ethoxylated
           urethanes (HEURs) in aqueous solution
    • Authors: Zhukang Du; Feng Wang; Xueyi Chang; Jun Peng; Biye Ren
      Pages: 131 - 141
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Zhukang Du, Feng Wang, Xueyi Chang, Jun Peng, Biye Ren
      Percec-type substituted benzyl alcohol mini-dendrons as new hydrophobic end-cappers can effectively improve the thickening performance of hydrophobically modified ethoxylated urethanes (HEURs) in aqueous solution. To demonstrate the effects of substituted structure of Percec-type mini-dendritic end groups on aggregation and rheological properties of HEURs in aqueous solution and latex, three model HEURs end-functionalized by mono-, di- and tri-substituted benzyl alcohol mini-dendrons were synthesized, respectively. For a reasonable comparison, the total carbon number of substituted alkyl tails is set to be 24 for the three mini-dendritic end groups: HOCH2-Ph-C24H49 (C24), HOCH2-Ph-(C12H25)2 (2C12) and HOCH2-Ph-(C8H17)3 (3C8), which respectively correspond to single-, two- and three-tail according to their substituted degrees. Interestingly, rheological properties of these HEURs in aqueous solution and latex significantly depend on the substituted degree of mini-dendritic hydrophobes. The high-substituted mini-dendritic hydrophobes help HEURs to form a strong physical network with high thickening performance and fast relaxation in both aqueous solution and latex, because shorter alkyl tails in high-substituted dendritic hydrophobes will lead to a smaller aggregation number and a lower rheological activation energy. This work not only provides new insights into the connection of networks in solutions of mini-dendron functionalized HEURs but also offers a new approach to preparation of high performance thickeners used in water-borne systems.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.022
      Issue No: Vol. 135 (2017)
       
  • Syntheses of aromatic polymers containing imidazolium moiety and the
           surface modification of a highly gas permeable membrane using the
           nanosheets
    • Authors: Yu Nagase; Botakoz Suleimenova; Chihiro Umeda; Kosuke Taira; Tatsuma Oda; Sayaka Suzuki; Yosuke Okamura; Shinichi Koguchi
      Pages: 142 - 153
      Abstract: Publication date: 17 January 2018
      Source:Polymer, Volume 135
      Author(s): Yu Nagase, Botakoz Suleimenova, Chihiro Umeda, Kosuke Taira, Tatsuma Oda, Sayaka Suzuki, Yosuke Okamura, Shinichi Koguchi
      Novel aromatic diamine monomer containing imidazolium group were synthesized to prepare polyimides and polyamide containing ionic liquid structure in the side chain by the polycondensation of the monomer with acid dianhydride or acid chloride. The glass transition temperatures, Tg, of the obtained polymers were in the range of 60–150 °C, and they exhibited the thermal stability up to 300 °C. The self-standing ultrathin films, so called nanosheets, of these aromatic polymers could be successfully prepared by spin-coating method. Then, the surface coating on the highly gas permeable membrane composed of polydimethylsiloxane graft copolyimide was carried out using the obtained nanosheets, and the effect of surface structure on the gas permeability and selectivity was investigated. As a result, the nanosheet coating on the highly gas permeable membrane with these polyimides containing imidazolium group was effective to improve the selectivity of CO2/N2 and O2/N2.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.12.016
      Issue No: Vol. 135 (2017)
       
  • Electrochromic and electrofluorochromic behavior of novel polyurea bearing
           oligoaniline and triphenylamine units
    • Authors: Ying Yan; Ningwei Sun; Xiaoteng Jia; Xincai Liu; Ce Wang; Danming Chao
      Pages: 1 - 7
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Ying Yan, Ningwei Sun, Xiaoteng Jia, Xincai Liu, Ce Wang, Danming Chao
      Electroactive materials have gained increasing attention for their intelligent applications. In this work, we report the design and synthesis of a novel electrochromic and electrofluorochromic dual-switching polyurea bearing oligoaniline and fluorescent triphenylamine units (PUOT). Cyclic voltammogram of PUOT exhibits two reversible redox couples at 0.96 V/0.73 V and 1.36 V/1.11 V (vs. Ag/AgCl reference electrode), ascribed to the redox transformation of oligoaniline and triphenylamine groups, respectively. In this wide potential window (0–1.6 V), the PUOT film reveals a unique multistage regulated electrochromic behavior with maximal transmittance contrast value of 38% switching from 0.0 V to 1.0 V, and partial transmittance contrast value of 14% (0–1.6 V) and 24% (1.0–1.6 V). Furthermore, its electrofluorochromic behavior has also been disclosed at the potential range of 0–1.0 V, which demonstrates that the oligoaniline groups should be served as electroactive units in this electrofluorochromic system. Our research not only presents a deep understanding of the optical-electrical modulation mechanism but also paves the way for their future applications.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.041
      Issue No: Vol. 134 (2017)
       
  • Colorless polyimides derived from isomeric dicyclohexyl-tetracarboxylic
           dianhydrides for optoelectronic applications
    • Authors: Xiaofan Hu; Hongliang Mu; Yongxia Wang; Zhen Wang; Jingling Yan
      Pages: 8 - 19
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Xiaofan Hu, Hongliang Mu, Yongxia Wang, Zhen Wang, Jingling Yan
      Two isomers of conventional cis-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride (4,4′-HBPDA), i.e. dicyclohexyl-2,3′,3,4′-tetracarboxylic dianhydride (3,4′-HBPDA) and dicyclohexyl-2,2′,3,3′-tetracarboxylic dianhydride (3,3′-HBPDA), were prepared through a four-step procedure. The data from single crystal X-ray diffraction revealed that 3,3′-HBPDA possessed higher structural rigidity/linearity than 4,4′-HBPDA. The one-step polycondensation of isomeric HBPDAs with commercial diamines enabled the synthesis of alicyclic polyimides. The isomer effects of the dianhydrides on the properties of resulting polyimides were studied in detail. For certain diamines, 3,3′-HBPDA-derived polyimides possessed higher glass transition temperatures (T g ) and better dimensional stability compared with those from 4,4′-HBPDA and 3,4′-HBPDA. These phenomena could be attributed to the higher structural rigidity/linearity of 3,3′-dicyclohexyl-tetracarboxydiimide, and restricted rotation of 3-substituted cyclohexylimide. Owing to the asymmetric structures and suppressed rotation of 3-substituted cyclohexylimides, 3,4′-HBPDA-based polymers exhibited higher T g , improved dimensional stability, and enhanced solubility compared with 4,4′-HBPDA-based ones. Furthermore, all the isomeric HBPDA-derived polyimides were essentially colorless with excellent optical transparency in the UV–Visible region. The excellent overall properties of polyimides from 3,3′-HBPDA and 3,4′-HBPDA made them promising candidate materials for optoelectronic applications.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.042
      Issue No: Vol. 134 (2017)
       
  • Design of thermoresponsive poly(ionic liquid) gels containing proline
           units to catalyse aldol reaction in water
    • Authors: Akiyoshi Okafuji; Yuki Kohno; Nobuhumi Nakamura; Hiroyuki Ohno
      Pages: 20 - 23
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Akiyoshi Okafuji, Yuki Kohno, Nobuhumi Nakamura, Hiroyuki Ohno
      Ionic liquid monomers and a proline-containing monomer were copolymerised in the presence of cross-linker to form ionic liquid polymer gels that show lower critical solution temperature-type phase change in water. The obtained gels were utilised as catalysts for aldol reaction in water. Since proline-catalysed aldol reaction is composed of three equilibrium steps including dehydration condensation reaction and hydrolysis reaction, yield of product was affected by the water content around the proline unit in the gel. Since thus prepared ionic liquid polymer gels showed the thermo-responsive change in water content, the product yield was found to be affected by the temperature around the phase transition temperature.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.047
      Issue No: Vol. 134 (2017)
       
  • Evolution of structural mechanisms in thermoplastic polyimide (BTDA-DAH)
           from amorphous precursors as revealed by real-time uniaxial
           mechano-optical behavior
    • Authors: I. Offenbach; S. Gupta; R. Ma; G. Treich; G.A. Sotzing; R.A. Weiss; M. Cakmak
      Pages: 24 - 34
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): I. Offenbach, S. Gupta, R. Ma, G. Treich, G.A. Sotzing, R.A. Weiss, M. Cakmak
      The real-time mechano-optical behavior of Polyimide 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) 1,6-diaminohexane (DAH) [PI(BTDA-DAH)] films during uniaxial deformation was investigated in the glassy and rubbery states as a function of temperature and stretch rate to understand the stretching characteristics of the polymer and elucidate the structural evolution. The study combined real-time spectral birefringence with true stress and true strain measurements and the data were further augmented by offline DSC and WAXD measurements. During deformation near glass transition temperature, initial photoelastic regime exhibiting very small slope is followed by regimes II and III. As the deformation temperature increases, the initial photoelastic regime disappears and gives way to temperature-independent regime I following classic stress-optical behavior. Regime I is followed by either a negative deviation from SOR into regime IIIa at lower deformation temperatures, or a positive deviation from SOR into regime II at higher deformation temperatures which eventually transitions into regime IIIc at large strains. The polymer was essentially amorphous in regime I. As the deformation increased, strain-induced crystallization occurred in regime II where crystallinity as high as 24% was achieved. The strain-induced crystals enhanced network connectivity and increased the rate of polymer chain orientation before transitioning to regime IIIc. Under conditions where regime II was not observed, a linear mechano-optical response in regime I extended to higher deformations before transitioning into regime IIIa where the highly oriented chains exhibited a “nematic-like” order with translational disorder along the chain directions. Based on the above observations a schematic for the structural evolution of PI(BTDA-DAH) during uniaxial deformation was proposed.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.052
      Issue No: Vol. 134 (2017)
       
  • Shape memory and self-healing materials from supramolecular block polymers
    • Authors: Jiuyang Zhang; Mengmeng Huo; Min Li; Tuoqi Li; Naixu Li; Jiancheng Zhou; Jing Jiang
      Pages: 35 - 43
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Jiuyang Zhang, Mengmeng Huo, Min Li, Tuoqi Li, Naixu Li, Jiancheng Zhou, Jing Jiang
      Shape memory thermoplastics are an important class of engineering polymers with smart characteristics. A series of diblock polymers, polymethylmethacrylate-b-poly(butylacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid) (PMMA-b-P(BA-co-AMPS)) with varying molecular weights and compositions were conveniently synthesized. The monomer selection as well as the design of molecular architecture facilitated microphase separation in the prepared polymers, leading to two networks formed by the vitrified PMMA domain and the supramolecular interactions from the AMPS component, respectively. As a result, these block polymers exhibited excellent shape memory property (shape recovery ratio: 95%). Besides, the materials were also mechanically tough with an outstanding breaking strain of around 500% and a high tensile strength over 10 MPa. Furthermore, these shape memory polymers (SMPs) were built merely relying on physical interactions, retaining the thermal processability of engineering thermoplastics: it was facile to melt compound the materials into various desired shapes (dog-bone, disk, and film, etc.). More importantly, the prepared SMPs also showed exceptional self-healing capability under ambient conditions, benefited from the supramolecular interactions (ionic interactions) within the polymer network. This work elucidates a new path towards fabricating multifunctional low-cost shape-memory materials for a host of industrial applications.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.043
      Issue No: Vol. 134 (2017)
       
  • Synthesis and characterization of a new poly(dithieno (3,2-b:2′, 3′-d)
           pyrrole) derivative conjugated polymer: Its electrochromic and biosensing
           applications
    • Authors: Hacer Azak; Huseyin Bekir Yildiz; Buket Bezgin Carbas
      Pages: 44 - 52
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Hacer Azak, Huseyin Bekir Yildiz, Buket Bezgin Carbas
      Synthesis and electropolymerization of a new conjugated dithieno(3,2-b:2′,3′-d) pyrole (DTP) derivative, namely, 2-(2-(2-(4H-dithieno[3,2-b:2′,3′-d]pyrrol-4-yl)ethoxy)ethoxy)ethanamine, (DTP-alkoxy-NH2) monomer are presented. The electrochemical, spectroelectrochemical effects and biosensor capability towards to glucose oxidase enzyme of P(DTP-alkoxy-NH2) polymer film are investigated in detail during the placement of alkoxy-NH2 functional unit in the polymer. Electrochemical and optical results between neutral and oxidized states of the polymer film show that (P(DTP-alkoxy-NH2)) has reversibly multielectrochromic behaviors. Furthermore, glucose oxidase enzyme (GOx) is covalently immobilized on Au electrodes modified with P(DTP-alkoxy-NH2) conducting polymer. This enzyme is entrapped into conducting polymer during electropolymerization of DTP monomer on the electrodes. Some characterization parameters (Maximum reaction rate, Michaelis–Menten constants, temperature, pH and operational stabilities) for this kind of biosensor application is also determined.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.044
      Issue No: Vol. 134 (2017)
       
  • Ring-opening polymerization of diepoxides as an alternative method to
           overcome PEG dilemma in gene delivery
    • Authors: Ya-Ping Xiao; Ji Zhang; Yan-Hong Liu; Xiao-Chuan Chen; Qing-Ying Yu; Chao-Ran Luan; Ju-Hui Zhang; Xi Wei; Xiao-Qi Yu
      Pages: 53 - 62
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Ya-Ping Xiao, Ji Zhang, Yan-Hong Liu, Xiao-Chuan Chen, Qing-Ying Yu, Chao-Ran Luan, Ju-Hui Zhang, Xi Wei, Xiao-Qi Yu
      Gene therapy has shown great potential in the treatment of various diseases, and the development of low-toxic and efficient gene carriers is still one of the burning issues for gene therapy. PEGylation is generally regarded as an efficient strategy to improve the biocompatibility of non-viral vectors. However, PEGylation also led to several problems such as lower cellular uptake, difficult endosomal escape and much reduced transfection efficiency, which was described as “PEG dilemma”. We herein devote to the development of polymeric gene vectors that can overcome such dilemma via diepoxide ring-opening polymerization (DEROP) of low molecular weight PEI, and unmodified PEI and PEG-grafted PEI were used for comparison. Transfection experiments with various concentrations of serum revealed that the DEROP polymers gave much higher transfection efficiency together with better serum tolerance than PEI and PEGylated ones. Protein adsorption and flow cytometry assays further proved their better serum resistance. Besides, confocal microscopy suggested that the polyplexes formed from these polymers could escape from endosome/lysosome more efficiently than those derived from PEGylated material. In vivo biochemical studies also reflect good biocompatibility of the DEROP polymers. Results demonstrate that such polymer construction strategy gave cationic materials with both high transfection efficiency and improved biocompatibility, and afforded an effective way to overcome PEG dilemma.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.059
      Issue No: Vol. 134 (2017)
       
  • Aliphatic-aromatic poly(carbonate-co-ester)s containing biobased furan
           monomer: Synthesis and thermo-mechanical properties
    • Authors: Xiaodong Cai; Xiangui Yang; Hua Zhang; Gongying Wang
      Pages: 63 - 70
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Xiaodong Cai, Xiangui Yang, Hua Zhang, Gongying Wang
      Aliphatic-aromatic poly(carbonate-co-ester) random copolymers poly(butylene carbonate-co-furandicarboxylate)s (PBCFs) with different composition had been prepared from dimethyl carbonate (DMC), 1,4-butanediol (BD) and bio-based dimethyl furan-2,5-dicarboxylate (DMFA) by two-step melt polycondensation method. A series of characterization results can be explained as follows: the varying melting temperature (T m) and enthalpy (ΔH m) displayed that the copolymers were strongly dependent upon the compositions of butylene carbonate (BC) and butylene furandicarboxylate (BF) units. In addition, glass transition temperature (T g) noticeably increased with the content of BF units increasing, which agreed with Fox equation; a comparative kinetics research of isothermal crystallization of homopolymer and copolymers with different composition displayed that the existence of BF units could accelerate the crystallization rate of PBC. Furthermore, all of PBCFs exhibited a typical isodimorphic cocrystallization behavior, whose crystal lattice structure shifted from PBC type crystal to PBF type; the thermal stability of PBCFs also expressed to be enhanced during the process of the increasing BF unit content; last but not the least, the mechanical performances could be easily by adjusting the feed components.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.058
      Issue No: Vol. 134 (2017)
       
  • Polymersomes with high loading capacity prepared by direct self-assembly
           of block copolymers in drugs
    • Authors: Fang-Yu Lin; Chih-Yang Cheng; Yu-Hao Chuang; Shih-Huang Tung
      Pages: 117 - 124
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Fang-Yu Lin, Chih-Yang Cheng, Yu-Hao Chuang, Shih-Huang Tung
      We develop a new method to prepare block copolymer vesicles with high loading capacity of drugs which can then be released in a controlled manner. The block copolymers, including PS-b-PAA, PS-b-PEO, and biocompatible PCL-b-PEO, can directly self-assemble into vesicles in aspirin and encapsulate aspirin by solvent annealing with ethanol which imparts mobility to the originally solid block copolymers and aspirin molecules. Aspirin associates with the hydrophilic blocks after premixing, firstly leading to the formation of bilayer structures. During solvent annealing, the bilayers are wrapped into vesicles to enclose aspirin that fills the cores of the vesicles. The interactions between block copolymers and aspirin were probed by FT-IR, and the formation of aspirin-loaded vesicles were confirmed by transmission electron microscopy and dynamic light scattering. The loading content of aspirin in the extracted vesicles is 59 ± 5%, higher than that of conventional vesicles formed in liquid systems with dilute drugs. The release rate and final release amount of aspirin from vesicles in aqueous solutions can be controlled by addition of different amount of n-dioxane or by changing pH values.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.060
      Issue No: Vol. 134 (2017)
       
  • Predictive simulation of non-steady-state transport of gases through
           rubbery polymer membranes
    • Authors: Marielle Soniat; Meron Tesfaye; Daniel Brooks; Boris Merinov; William A. Goddard; Adam Z. Weber; Frances A. Houle
      Pages: 125 - 142
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Marielle Soniat, Meron Tesfaye, Daniel Brooks, Boris Merinov, William A. Goddard, Adam Z. Weber, Frances A. Houle
      A multiscale, physically-based, reaction-diffusion kinetics model is developed for non-steady-state transport of simple gases through a rubbery polymer. Experimental data from the literature, new measurements of non-steady-state permeation and a molecular dynamics simulation of a gas-polymer sticking probability for a typical system are used to construct and validate the model framework. Using no adjustable parameters, the model successfully reproduces time-dependent experimental data for two distinct systems: (1) O2 quenching of a phosphorescent dye embedded in poly(n-butyl(amino) thionylphosphazene), and (2) O2, N2, CH4 and CO2 transport through poly(dimethyl siloxane). The calculations show that in the pre-steady-state regime, permeation is only correctly described if the sorbed gas concentration in the polymer is dynamically determined by the rise in pressure. The framework is used to predict selectivity targets for two applications involving rubbery membranes: CO2 capture from air and blocking of methane cross-over in an aged solar fuels device.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.055
      Issue No: Vol. 134 (2017)
       
  • Rheology provides insight into flow induced nano-structural breakdown and
           its recovery effect on crystallization of single and hybrid carbon
           nanofiller filled poly(lactic acid)
    • Authors: Amir Rostami; Mehdi Vahdati; Younes Alimoradi; Mohammad Karimi; Hossein Nazockdast
      Pages: 143 - 154
      Abstract: Publication date: 3 January 2018
      Source:Polymer, Volume 134
      Author(s): Amir Rostami, Mehdi Vahdati, Younes Alimoradi, Mohammad Karimi, Hossein Nazockdast
      Despite the indispensable contribution of crystallization to the final properties of poly(lactic acid) (PLA), the combined effect of steady shear and nanofiller(s) remains mostly unsettled. This work employed a combination of steady shear and oscillatory rheological measurements to study shear induced nano-structural breakdown and subsequent nanoparticle orientation and overall structural recovery in PLA nanocomposites containing functionalized, single and hybrid carbon nanofillers (fCNTs & fGnPs) with different dimensionalities. Similar rheological measurements were used to study the effect of the flow induced nanoparticle orientation on nonisothermal as well as isothermal crystallization of PLA under both applied pre-shear and quiescent conditions. It was found that addition of the carbon nanofillers into PLA had a significant intensifying effect on the flow induced contribution to the acceleration of the crystallization kinetics, particularly after a pre-shear. These findings could be explained in the light of the simultaneous increase in nucleation density and amplification of flow induced molecular orientation driven by the carbon nanofillers. In the case of the nanocomposites containing hybrids of the nanofillers showed greater enhancing effect on crystallization of PLA compared to mixture law predictions. This was attributed to the favorable effect of 2D fGnPs on the dispersion of 1D fCNTs which could, in turn, lead to the availability of a larger surface area of nanofillers and therefore stronger nanoparticle induced molecular orientation. Finally, the effect of increasing pre-shear rate on the flow sensitivity parameter defined as kss/kq was found to be synergistic for all nanocomposite samples.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.062
      Issue No: Vol. 134 (2017)
       
  • Unilamellar polyion complex vesicles (PICsomes) with tunable
           
    • Authors: Omer F. Mutaf; Yasutaka Anraku; Akihiro Kishimura; Kazunori Kataoka
      Pages: 1 - 7
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Omer F. Mutaf, Yasutaka Anraku, Akihiro Kishimura, Kazunori Kataoka
      Polyion complex vesicles (PICsomes) are characterized by their unique three-layered semipermeable nanomembrane structures, in which a unilamellar PIC layer is sandwiched by poly(ethylene glycol) layers, and have gathered much attention as nano-scaled drug vehicles. Herein, the crosslinking degree of the nanomembrane in the PICsome was controlled systematically for the first time. Permeability of the PICsome nanomembrane was evaluated through a kinetic study of the release of macromolecular cargoes from the PICsome. The degree of crosslinking in the nanomembrane successfully regulated the release behavior. Moreover, the shape and size of the macromolecular solutes were found to be critical factors determining their transport from the inner aqueous phase of the PICsome to the external environment. The results indicate that the unique three-layered structure of PICsome membranes plays a key role in modulating solute transport. These findings will provide a rational strategy for the development of nanomembrane-based controlled-release systems.
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      PubDate: 2017-11-17T01:53:03Z
      DOI: 10.1016/j.polymer.2017.10.062
      Issue No: Vol. 133 (2017)
       
  • On the role of nano-silica in the kinetics of peroxide vulcanization of
           ethylene propylene diene rubber
    • Authors: Seyed Mostaffa Hosseini; Mehdi Razzaghi-Kashani
      Pages: 8 - 19
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Seyed Mostaffa Hosseini, Mehdi Razzaghi-Kashani
      This work discusses different roles of nano-silica in the kinetics of peroxide vulcanization of ethylene propylene diene (EPDM) rubber for the first time. Initially, it was shown that silica does not participate in the vulcanization mechanism by chemical bonding to other intermediates. Non-isothermal differential scanning calorimeter revealed that the enthalpy of vulcanization, proportional to the crosslinking reaction, goes through a minimum as silica loading increases. Therefore, silica has two roles affecting kinetics of peroxide vulcanization of EPDM: physical effect on the rate of crosslinking reaction through reduced dynamics of rubber chains and catalytic effect on the decomposition of peroxide. In the low-temperature isothermal vulcanization, the enthalpy of vulcanization decreased monotonically, indicating that the physical effect is dominant. The extent of physical effect was correlated to the immobilized bound rubber resulting from the filler-polymer and filler-filler interactions. However, at high-temperature isothermal or non-isothermal vulcanization, the catalytic effect surmounts the physical one.
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      PubDate: 2017-11-17T01:53:03Z
      DOI: 10.1016/j.polymer.2017.10.061
      Issue No: Vol. 133 (2017)
       
  • Synthesis and mechanical properties of flame retardant vinyl ester resin
           for structural composites
    • Authors: Siddharth Dev; Priyank N. Shah; Yipei Zhang; David Ryan; Christopher J. Hansen; Yongwoo Lee
      Pages: 20 - 29
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Siddharth Dev, Priyank N. Shah, Yipei Zhang, David Ryan, Christopher J. Hansen, Yongwoo Lee
      Halogen-based fire retardants are often used to reduce flammability and improve the fire resistance properties of polymers and fiber-reinforced polymer composites (FRPs). Brominated vinyl ester resins (Br-VERs) are a class of halogenated polymer matrices that are economically viable, high performance materials that are widely utilized in composites for specialty applications, such as the fabrication of hulls in naval vessels. In this work, Br-VE polymer is synthesized from tetrabromobisphenol A (TBBPA) and glycidyl methacrylate (GMA) precursors, and which can be derived from the wastes of the biodiesel and wood pulp industries, respectively. The Br-VE reaction products are analyzed by 1H NMR and the presence of unreacted (nonfunctional), monofunctional and difunctional TBBPA are confirmed. A baseline formulation of difunctional Br-VE and styrene (40 wt %) is mixed with a commercial brominated vinyl ester resin (Derakane 510-40A) in ratios of 20, 50 and 80 pph. Two reduced styrene content formulations of Br-VER (30 wt % styrene and 20 wt % styrene) were also prepared. The thermomechanical properties of all seven neat resin formulations were investigated using differential scanning calorimetry (DSC), rheology and dynamic mechanical analysis (DMA). The autocatalytic cure kinetics parameters and chemorheological behavior enable development of a cure cycle for the thermosetting resin. The DMA results demonstrate that all resin formulations comprising Br-VER exhibit improved mechanical performance as compared to the commercial vinyl ester resin.
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      PubDate: 2017-11-17T01:53:03Z
      DOI: 10.1016/j.polymer.2017.11.017
      Issue No: Vol. 133 (2017)
       
  • Aliphatic flexible spacer length controls photomechanical response in
           compact, ordered liquid crystalline polymer networks
    • Authors: Amir Skandani; J. Arul Clement; Stephanie Tristram-Nagle; M. Ravi Shankar
      Pages: 30 - 39
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Amir Skandani, J. Arul Clement, Stephanie Tristram-Nagle, M. Ravi Shankar
      The aliphatic spacer length connected to the rigid mesogenic cores is shown to control the structural organization and mechanical actuation in response to light-stimulus in azobenzene-functionalized liquid crystalline polymers networks. The spacer lengths in the mesogenic host (non-photochromic) and in the photo-active azobenzene-functionalized cross linker are parametrically varied to create monodomain liquid crystalline samples. A suite of thermomechanical, photomechanical and structural characterization is used to characterize the binary co-polymers. The photomechanical responses are compared by calculating a figure-of-merit – Photocompliance (Cp). This parameter, Cp, which characterizes the incremental strain generated in response to unit intensity of irradiation (W/cm2), is found to correlate strongly with the Sxray order parameter and the D-spacings. We show that compact (smaller D) and higher ordering of the mesogens that result in copolymers with longer flexible spacers manifest greater photomechanical activity.
      Graphical abstract image

      PubDate: 2017-11-17T01:53:03Z
      DOI: 10.1016/j.polymer.2017.10.050
      Issue No: Vol. 133 (2017)
       
  • Development of complete silica thin films based on functional
           hyperbranched polyalkoxysiloxanes
    • Authors: Garima Agrawal; Xiaomin Zhu; Martin Moeller; Veena Choudhary
      Pages: 40 - 49
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Garima Agrawal, Xiaomin Zhu, Martin Moeller, Veena Choudhary
      A precursor polymer has been designed on the basis of an idea of conversion of hyperbranched polymer to an inorganic substance by lithographic procedure. For this purpose hyperbranched polyethoxysiloxane (PEOS) was synthesized via a one-pot catalytic condensation reaction of tetraethoxysilane with acetic anhydride. PEOS was modified with cyclohexanol via a catalytic trans-esterification reaction. The products were characterized by means of 1H and 29Si NMR spectroscopy, elemental analysis and size exclusion chromatography. The thin silica films were formed by spin-coating of chloroform solutions of PEOS and cyclohexanol-modified PEOS (CH-PEOS) on silicon wafer substrates with subsequent H2-plasma treatment. CH-PEOS layer containing a photoacid could be cross-linked upon UV-irradiation. This approach was used to develop patterned thin silica films, which were analyzed by field emission scanning electron microcopy and atomic force microscopy. Well defined sharp silica patterns were obtained and further conversion of the layer to pure silica was carried out by removing organic species using H2 plasma treatment.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.019
      Issue No: Vol. 133 (2017)
       
  • Synthesis of poly(benzobisoxazole-co-imide) and fabrication of
           high-performance fibers
    • Authors: Yang Cheng; Jie Dong; Cairan Yang; Tingting Wu; Xin Zhao; Qinghua Zhang
      Pages: 50 - 59
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Yang Cheng, Jie Dong, Cairan Yang, Tingting Wu, Xin Zhao, Qinghua Zhang
      A novel heterocyclic and plank-shape diamine monomer, 2,6-(4,4′-diaminodiphenyl) benzo[1,2-d:5,4-d'] bisoxazole (PBOA), was successfully synthesized from readily available compounds of 4,6-diaminoresorcinol dihydrochloride (DAR) and p-aminobenzoic acid (PABA). A series of poly(benzobisoxazole-co-imide) (PBOI) fibers based on 3,3′,4,4′-biphenyltetracarboxylic anhydride (BPDA), 4,4′-diaminodiphenyl ether (ODA) and PBOA were fabricated via a two-step wet-spinning method. PBOA was characterized in detail, and the effect of the monomer in the polymer backbones on the fibers' microstructure and properties were described. 2D wide-angle X-ray diffraction indicated that the incorporated PBOA in the BPDA-ODA polyimide backbone is beneficial for forming well-defined crystalline regions in the resulted fibers during the thermal stretching process and significantly improving the crystallinity and crystal orientation of the drawn PBOI fibers. Small-angle X-ray scattering patterns of the drawn PBOI fibers suggested the presence of typical periodic lamellar crystal in the fibers. It is shown that increasing PBOA contents will result in higher values of the long period (L) and the lamellar thickness (l C). Maximum improvements of 153% in tensile strength and 282% in modulus were achieved when increasing the molar content of PBOA in the mixed diamine from 10 mol% to 50 mol%. Correspondingly, the temperature at the maximum degradation rate (T d-max ) and glass transition temperature (T g ) of resulted PBOI fibers in nitrogen increased by 28 and 30 °C, respectively, making these novel polymeric fibers as good reinforcements in fabricating advanced composites.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.015
      Issue No: Vol. 133 (2017)
       
  • Efficient benzodithiophene and thienopyrroledione containing random
           polymers as components for organic solar cells
    • Authors: Özge Azeri; Ece Aktas; Cagla Istanbulluoglu; Serife O. Hacioglu; Sevki Can Cevher; Levent Toppare; Ali Cirpan
      Pages: 60 - 67
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Özge Azeri, Ece Aktas, Cagla Istanbulluoglu, Serife O. Hacioglu, Sevki Can Cevher, Levent Toppare, Ali Cirpan
      Benzodithiophene and thienopyrroledione containing two random copolymers were designed and synthesized. Electrochemical and optical studies prove that these copolymers could be candidates for organic solar cells applications. The HOMO and LUMO values were determined using cyclic voltammetry as −5.53 and −3.43 eV for P1 and -5.54 and −3.53 eV for P2, respectively. The optical band gaps of the polymers were calculated as 2.10 and 2.01 eV using UV-VIS spectroscopy for P1 and P2, correspondingly. Bulk-heterojunction solar cells were constructed with the configuration of ITO/PEDOT:PSS/Polymer:PC71BM/LiF/Al and the synthesized polymers were used as the electron donors and PC71BM as the electron acceptor in the active layer. The best performance was observed for device of P2 1:2 (w:w) ratio with a V oc 0.80 V, a J sc of 14.02 mA/cm2, a fill factor of 52%, and a PCE of 5.83% under standard AM 1.5 G at 100 mW/cm2.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.024
      Issue No: Vol. 133 (2017)
       
  • Surface and mechanical properties of waterborne polyurethane films
           reinforced by hydroxyl-terminated poly(fluoroalkyl methacrylates)
    • Authors: Wei Yang; Xu Cheng; Haibo Wang; Yuansen Liu; Zongliang Du
      Pages: 68 - 77
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Wei Yang, Xu Cheng, Haibo Wang, Yuansen Liu, Zongliang Du
      Novel waterborne fluorinated polyurethane (WFPU) based on hydroxyl-terminated poly(fluoroalkyl methacrylates) (HTPFMA) was prepared successfully. The microstructures and micro-phase separation of WFPU were evaluated through infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic mechanical analysis (DMA), and scanning electron microscope (SEM). FT-IR revealed that the H-bonded carbonyl in hard domains increased with the increasing of fluorine content, resulting in enhancing the extent of micro-phase separation between hard and soft segments. XRD results indicated that the crystallinity of hard segment was enhanced with the increasing of fluorine content. The direct visual microstructures by SEM showed that the micro-phase separation was more significant when the fluorine content increased. DMA also revealed strengthened micro-phase separation with increasing fluorine content. The studies of mechanical properties confirmed that WFPU based on HTPFMA had outstanding mechanical properties. The effects of fluorine content on the static contact angles, surface free energy, and surface composition were also studied. The static contact angles of the WFPU films against water and methylene iodide reached around 108° and 84°, respectively. X-ray photoelectron spectroscopy (XPS) confirmed that the fluorine surface enrichment factor in the outermost 10 nm depth was about 10–18 fold higher than its bulk level.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.021
      Issue No: Vol. 133 (2017)
       
  • Thermally healable and remendable lignin-based materials through Diels –
           Alder click polymerization
    • Authors: Pietro Buono; Antoine Duval; Luc Averous; Youssef Habibi
      Pages: 78 - 88
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Pietro Buono, Antoine Duval, Luc Averous, Youssef Habibi
      We report in this work the preparation and in-depth characterization of thermo-reversible healable materials based on lignin, a major naturally occurring aromatic biopolymer. Following an environmentally friendly chemical pathway, a derivative of soda lignin (SL) bearing maleimide groups and poly-functional furan linkers were clicked through the furan – maleimide Diels – Alder (D-A) polymerization in a solvent free media and without the use of catalyst. The furan linkers were obtained by the thiol – epoxy reaction between furfuryl glycidyl ether and thiols of functionalities from 2 to 4. The different degree of substitution of maleimide lignin derivatives and linker functionalities allowed the tuning of the thermo-mechanical properties of the resultant materials. The latter exhibit on demand thermally induced disassembly and reassembly of the polymeric networks when heated at 110–130 °C and then cured at 60 °C, providing controlled self-healing properties and an efficient reprocessing with a limited impact on the thermo-mechanical properties and the thermal stability of the final materials. This study provides interesting perspectives for the production of renewable lignin-based aromatic polymers, demonstrating that an effective chemical modification together with tailored molecular architectures could pave the way for the development of high value-added materials from this underused aromatic feedstock.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.022
      Issue No: Vol. 133 (2017)
       
  • Plasticisation and compatibilisation of poly(propylene) with poly(lauryl
           acrylate) surface modified MWCNTs
    • Authors: Jaipal Gupta; Chaoying Wan; David M. Haddleton; Tony McNally
      Pages: 89 - 101
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Jaipal Gupta, Chaoying Wan, David M. Haddleton, Tony McNally
      Poly(lauryl acrylate) P[LA] synthesised using Cu(0)-mediated polymerisation was used to non-covalently functionalise multi-walled carbon nanotubes (MWCNTs) achieved via combined CH-π interactions and physical wrapping. The inclusion of P[LA] competed with the attractive van der Waals forces between MWCNTs altering interfacial interactions between neighbouring CNTs and, assisted their dispersion and distribution in a poly(propylene) (PP) matrix, confirmed from SEM/HR-TEM imaging and oscillatory rheology measurements. A rheological percolation threshold measured for composites of unmodified MWCNTs and PP at ∼0.5 wt% was shifted to lower MWCNT concentrations (∼0.25 wt%) for P[LA] functionalised MWCNTs. Addition of P[LA] also reduced the nucleating effect of MWCNTs for PP as a coating of P[LA] on the nanotube surfaces hindered trans-crystallisation of the PP. Evidence from static and dynamic mechanical measurements confirmed the P[LA] plasticised PP as both an increase in ductility and a decrease in the glass transition temperature (T g) of PP of up to 25 °C was obtained. Addition of unmodified MWCNTs to PP resulted in an increase in the DC electrical conductivity of PP of 15 orders of magnitude, from 10−14 S/m to 101 S/m for a MWCNT loading of 5 wt%. Non-covalent functionalisation of MWCNTs utilising P[LA] only degraded electrical conductivity by about 2 orders of magnitude across the composition range.
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      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.025
      Issue No: Vol. 133 (2017)
       
  • Highly stable and reduction responsive micelles from a novel polymeric
           surfactant with a repeating disulfide-based gemini structure for efficient
           drug delivery
    • Authors: Hyun-Chul Kim; Eunjoo Kim; Tae-Lin Ha; Se Geun Lee; Sung Jun Lee; Sang Won Jeong
      Pages: 102 - 109
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Hyun-Chul Kim, Eunjoo Kim, Tae-Lin Ha, Se Geun Lee, Sung Jun Lee, Sang Won Jeong
      The synthesis of a novel polymeric surfactant with a repeating disulfide-based gemini structure (poly(gemini surfactant)) and its micellar properties for GSH-dependent intracellular drug delivery are described. A linear polyethylene glycol (PEG) was end-functionalized with N-stearoylcysteine and the cysteine thiol groups of the telechelic surfactant were oxidized intermolecularly in the micellar state to produce poly(gemini surfactant). Compared with the telechelic surfactant, poly(gemini surfactant) possessed a lower critical micelle concentration and higher solubilization capacity for doxorubicin (DOX). Moreover, the poly(gemini surfactant) micelles revealed excellent colloidal stability against excess sodium dodecyl sulfate (SDS) as a micelle-destabilizing agent. Cytotoxicity experiments showed that poly(gemini surfactant) composed of PEG, cysteine, and stearic acid was virtually non-cytotoxic up to 100 mg L−1. In the presence of glutathione (GSH), poly(gemini surfactant) was degraded back into the telechelic surfactant, leading to the release of encapsulated DOX to induce cytotoxicity against cancer cells.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.032
      Issue No: Vol. 133 (2017)
       
  • Diffusion-assisted post-crosslinking of polymer microspheres containing
           epoxy functional groups
    • Authors: Joon-Suk Oh; Minsoo P. Kim; Joo-Hyung Kim; Hyunjong Son; Kyung-Heum Kim; Sang-Hoon Kim; Ji-Beom Yoo; Youngkwan Lee; Gi-Ra Yi; Jae-Do Nam
      Pages: 110 - 118
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Joon-Suk Oh, Minsoo P. Kim, Joo-Hyung Kim, Hyunjong Son, Kyung-Heum Kim, Sang-Hoon Kim, Ji-Beom Yoo, Youngkwan Lee, Gi-Ra Yi, Jae-Do Nam
      With a diffusion-assisted post-crosslinking method, polymer microspheres containing epoxy groups are crosslinked with ethylenediamine (EDA), gradually diffusing and reacting in the particles via amine/epoxy ring-opening reactions as confirmed by FT-IR and DSC results. Using a microcompression test, we find that the mechanical property (deformability under different applied force, breaking points, and recoverability) of the crosslinked microspheres is varied when different amounts of EDA are used in the system, resulting from different crosslinking density of the particles. An additional feature of the EDA treatment is to generate amine groups on the surface of the microspheres, enabling us to produce hybrid microspheres. We exploit them as immobilization sites for gold nanoparticles, forming gold-coated crosslinked microspheres. We also introduce a sequential functionalization method to fabricate crosslinked microspheres with selective functional groups on the surface. This approach can be a facile method to produce functional microspheres with controlled mechanical and surface properties.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.035
      Issue No: Vol. 133 (2017)
       
  • Thermoresponsive and pH triggered drug release of cholate functionalized
           poly(organophosphazene) – polylactic acid co-polymeric nanostructure
           integrated with ICG
    • Authors: Sivaraj Mehnath; Mariappan Rajan; Gnanasekar Sathishkumar; Rajendran Amarnath Praphakar; Murugaraj Jeyaraj
      Pages: 119 - 128
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Sivaraj Mehnath, Mariappan Rajan, Gnanasekar Sathishkumar, Rajendran Amarnath Praphakar, Murugaraj Jeyaraj
      This study demonstrates the development of pH and thermosresponsive nanoparticles (NPs) composed via cholic acid, PCPP-PLA hybrid polymer integrated with indocyanine green (ICG) for site specific delivery hydrophobic drug (paclitaxel). Drug and ICG were physically encapsulated by poly (bis(carboxyphenoxy)phosphazene) (PCPP)-poly lactic acid hybrid polymer. The hybrid polymer solution showed reversible gelation behaviour at the temperature between 37 °C and 20 °C and also it showed pH dependent drug release capability at acidic pH due to the pH responsive quenching effects of PCPP-PLA. The size (150–200 nm) and morphology of drug-loaded polymeric NPs were characterized using SEM and HR-TEM. Further, the release of loaded paclitaxel (PTX) from polymer was significantly sustained over 12 days. Drug release from the nanoparticles was effectively controlled by the mechanical strength of the polymer. All of these results demonstrate that pH triggered hybrid polymeric NPs are potential carriers for tumor-targeted drug delivery and also it exhibits great strength at 37 °C.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.020
      Issue No: Vol. 133 (2017)
       
  • On the properties of poly(isoprene-b-ferrocenylmethyl methacrylate) block
           copolymers
    • Authors: Sergey Chernyy; Jacob Judas Kain Kirkensgaard; Anders Bakke; Kell Mortensen; Kristoffer Almdal
      Pages: 129 - 136
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Sergey Chernyy, Jacob Judas Kain Kirkensgaard, Anders Bakke, Kell Mortensen, Kristoffer Almdal
      By combining poly(1,4-isoprene) (PI) with poly(ferrocenylmethyl methacrylate) (PFMMA) in a diblock copolymer structure by means of anionic polymerization we obtained narrowly dispersed PI-b-PFMMA copolymers with molecular weight ranging from 13000 to 62000 g/mol. The products were stable up to 228 °C, according to thermal gravimetry, which allowed us to further investigate their viscoelastic and X-ray scattering properties at elevated temperature by rheology and SAXS, respectively. For PI-b-PFMMA with total molecular weight 13400 g/mol a phase transition at 105 °C was identified leading to the segmental mixing at T > 105 °C and microphase separation at T < 105 °C. The microphase separated morphology acquired hexahonally packed cylinder (HEX) microstructure in bulk. The explanation of the ordered HEX morphology was derived from a quantification of the thermodynamic immiscibility between PI and PFMMA segments via random phase approximation theory yielding generally accepted dependency of the Flory-Huggins interaction parameter (χ) on temperature.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.036
      Issue No: Vol. 133 (2017)
       
  • Dynamic viscoelasticity of a series of poly(4-n-alkylstyrene)s and their
           alkyl chain length dependence
    • Authors: Satoru Matsushima; Atsushi Takano; Yoshiaki Takahashi; Yushu Matsushita
      Pages: 137 - 142
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Satoru Matsushima, Atsushi Takano, Yoshiaki Takahashi, Yushu Matsushita
      Dynamic viscoelastic measurements were performed for a series of poly(4-n-alkylstyrene)s with six different n-alkyl side chains, that is, methyl, ethyl, propyl, butyl, hexyl and octyl groups. Based on the time-temperature superposition principle, storage modulus G′, loss modulus G″ and loss tangent tan δ were shifted with horizontal shift factor a T and vertical shift factor b T, giving well superposed master curves for all the polymers. With increase of the number of carbon atoms, plateau modulus G N 0, which corresponds to G′ value at minimum tan δ, decreases, while entanglement molecular weight M e(=ρRT/G N 0) increases, where ρ is the polymer density, R is the gas constant and T is the absolute temperature. Degree of polymerization at onset of entanglement, N e, which defined as M e/M 0, where M 0 denotes the molecular weight of each monomer, also increases with increase of n-alkyl side chain length. Packing length estimated from the empirical equation by Fetters also increases with increase of n-alkyl lengths. These results are presumably due to large polymer chain thickness caused directly by substituents on phenyl rings of styrene units.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.10.065
      Issue No: Vol. 133 (2017)
       
  • A dynamic supramolecular polyurethane network whose mechanical properties
           are kinetically controlled
    • Authors: Xuegang Tang; Antonio Feula; Benjamin C. Baker; Kelly Melia; Daniel Hermida Merino; Ian W. Hamley; C. Paul Buckley; Wayne Hayes; Clive R. Siviour
      Pages: 143 - 150
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Xuegang Tang, Antonio Feula, Benjamin C. Baker, Kelly Melia, Daniel Hermida Merino, Ian W. Hamley, C. Paul Buckley, Wayne Hayes, Clive R. Siviour
      We report the synthesis and characterization of a kinetically controlled, thermoreversible supramolecular polyurethane whose mechanical properties depend unusually strongly on the processing history. Materials were prepared by solution casting, quenching and annealing of quenched material, allowing pronounced micro-structural evolution, which leads to rapid increases in modulus as determined by rheological analysis. Tensile tests showed that the quenched material is soft, weak and ductile (shear modulus ∼ 5 MPa, elongation ∼ 250%), but after annealing, at 70 °C for 1 h, it becomes stiffer, stronger and more brittle (∼20 MPa, ∼20%). FTIR and NMR spectroscopic analysis, coupled with MDSC and SAXS, were performed to investigate the network's dynamic structural changes. SAXS results suggest the presence of a lamellar structure in the sample when solution cast at high temperature, or annealed. This ordering is unique when compared to structurally-related supramolecular bisurethane and bisurea polymers, and may be the cause of the observed path dependence. These mechanical properties, which can be switched repeatedly by simple thermal treatments, coupled with its adhesion properties as determined from peel and tack tests, make it an excellent candidate as a recyclable material for adhesives and coatings.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.005
      Issue No: Vol. 133 (2017)
       
  • AIE-active florescent polymers: The design, synthesis and the cell imaging
           application
    • Authors: Lei Lei; Hengchang Ma; Yanfang Qin; Manyi Yang; Yucheng Ma; Tao Wang; Yuan Yang; Ziqiang Lei; Dedai Lu; Xiaolin Guan
      Pages: 151 - 159
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Lei Lei, Hengchang Ma, Yanfang Qin, Manyi Yang, Yucheng Ma, Tao Wang, Yuan Yang, Ziqiang Lei, Dedai Lu, Xiaolin Guan
      Fluorescence imaging, especially specific organelle imaging, has become a significant technology to comprehending cell transplantation, migration, division, fusion, and lysis. In this paper, we designed and synthesized a water soluble and fluorescent polymer named as Poly(AA-TPA-d), which was pH-responsive by the fluorescence channel due to the presence of poly acrylic acid as the polymer backbone. The research results demonstrated that Poly(AA-TPA-d) exhibits novel aggregation-induced-emission (AIE) property. Additionally, due to the hydrogen bond formation and C=O···π interactions between methyl acrylate groups, Poly(AA-TPA-d) was of excellent hydrogel formation ability. Moreover, Poly(AA-TPA-d) displayed good bio-compatibility with the living MPC5 cells and highly specific cytoplasm-targeting ability by MTT assay and cell staining experiment respectively.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.030
      Issue No: Vol. 133 (2017)
       
  • Investigation of the 3-hydroxyvalerate content and degree of crystallinity
           of P3HB-co-3HV cast films using Raman spectroscopy
    • Authors: Verena Jost; Matthias Schwarz; Horst-Christian Langowski
      Pages: 160 - 170
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Verena Jost, Matthias Schwarz, Horst-Christian Langowski
      The structural properties of extruded cast films of poly-3-hydroxybutyrate (P3HB) and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P3HB-co-3HV) were analysed by Raman spectroscopy. A sensitive band for the side chain of the 3HV was found at 844 cm−1 (νCC, νC-COO). Using an internal standard at 1101 cm−1 (νsC-O-C, ρCH3), a model for calculation of the 3HV content was developed. This was based on analysis of samples with a 3HV content of 0–12 mol%. Additionally, P3HB-co-3HV samples were tempered in order to create different degrees of crystallinity. The induced changes in the Raman spectra were analysed. The Raman model to determine the degree of crystallinity considers the sensitive band at 2999 cm−1 (νasCH2) and the internal standard at 1059 cm−1 (νC-O, νC-CH3, ρCH2). The investigated crystallinity was in a range of 0.69–0.86.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.026
      Issue No: Vol. 133 (2017)
       
  • Synthesis and characterization of hyperbranched polyimides from a novel
           B’B2-type triamine with tert-butyl side group
    • Authors: Lang Yi; Xiuming Wu; Chen Shu; Wei Huang; Deyue Yan
      Pages: 171 - 183
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Lang Yi, Xiuming Wu, Chen Shu, Wei Huang, Deyue Yan
      A novel triamine (1) with tert-butyl side group, N1,N1-bis(4-aminophenyl)-4-(tert-butyl)benzene-1,3-diamine, is synthesized and then polymerized with the dianhydride 6FDA (A2) at the different feed molar ratio. Monitoring by 1H NMR spectrum, the reactivity of 3-amino group with ortho-tert-butyl is much lower than that of 4′/4″-amino groups in triamine 1. Thus AB2-type amic acid (B’A2 intermediates) can be formed rapidly in situ when the polymerization is processed at 20 °C and the molar ratio of 1/6FDA is 1:2. Subsequently with increasing the polymerization temperature, 3-amino group with ortho-tert-butyl in AB2-type intermediates is activated and self-polycondensed with anhydride groups to produce hyperbranched polyimide (HBPI) without gelation. This indicates that it’s an effective approach to decrease the reactivity of amino groups in triamine by introducing tert-butyl into its ortho-position and HBPIs can be prepared conveniently through the method of ‘A2+B’B2′ based on the principle of unequal reactivity of functional groups.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.029
      Issue No: Vol. 133 (2017)
       
  • Effect of Fe3O4 NPs on micellization and release behavior of CBABC-type
           pentablock copolymer
    • Authors: Aniruddha Pal; Sagar Pal
      Pages: 184 - 194
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Aniruddha Pal, Sagar Pal
      Amphiphilic pentablock copolymer (CBABC-type) based on poly(propylene oxide), poly(methyl methacrylate) and poly(acrylic acid) has been synthesized through ring opening polymerization (ROP) and reversible addition-fragmentation chain transfer polymerization (RAFT) techniques. Gel permeation chromatography (GPC) results envisage the control nature of polymerization. Structural property and thermal behavior of the pentablock copolymer have been analyzed through various characterization techniques. Further, a novel nanocomposite comprised of iron oxide nanoparticles (Fe3O4 NPs) and penta block copolymer has been successfully developed and characterized using various techniques. Vibrating Sample Magnetometer (VSM) results indicate that the presence of copolymer has no adverse effect towards the magnetic property of Fe3O4 NPs. Comparative studies towards micellar stability and pH-triggered release behavior of pentablock copolymer and nanocomposite have been discussed in detail.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.034
      Issue No: Vol. 133 (2017)
       
  • Synthesis of new
           2,6-bis(6-fluoro-2-hexyl-2H-benzotriazol-4-yl)-4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene
           based D-A conjugated terpolymers for photovoltaic application
    • Authors: M.L. Keshtov; S.A. Kuklin; A.R. Khokhlov; I.O. Konstantinov; N.V. Nekrasova; Zhi-yuan Xie; Ganesh D. Sharma
      Pages: 195 - 204
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): M.L. Keshtov, S.A. Kuklin, A.R. Khokhlov, I.O. Konstantinov, N.V. Nekrasova, Zhi-yuan Xie, Ganesh D. Sharma
      Two D1-A-D2-A conjugated terpolymers with same A (fluorinated benzotriazole, fBTz), D2 (dithienosilole, DTS) and different D1 (bis(undecyl)benzo[2,1-b:3,4-b']dithiophene for P1 and didodecyloxy-benzo[1,2-b:4,5-b']dithiophene for P2) were synthesized and their optical and electrochemical properties were investigated. Compared to P1, the P2 with didodecyloxy side chains in benzodithiophene showed strong interchain π-π interaction, more redshifted absorption spectrum and higher molar extinction coefficient. The X-ray diffraction results indicated their excellent crystallinity and molecular stacking features, especially P2 containing didodecyloxy side chains in BDT. These two terpolymers were used as donor along with PC71BM for the fabrication of bulk heterojunction polymer solar cells. After the optimization of active layers, i.e. weight ratios of terpolymer to PC71BM and concentration of solvent additive (DIO) in the host solvent, the resultant polymer solar cells showed overall power conversion efficiency of 6.95% (Jsc = 12.23 mA/cm2, Voc = 0.93 V and FF = 0.61) and 8.14% (Jsc = 14.08 mA/cm2, Voc = 0.85 V and FF = 0.68) for P1 and P2 based bulk heterojunction active layers, respectively. The higher power conversion efficiency of P2 based polymer solar cell than P1 based counterpart, may be attributed to the more exciton dissociation, better nanoscale morphology and higher hole mobility in P2:PC71BM active layer than P1:PC71BM.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.012
      Issue No: Vol. 133 (2017)
       
  • The influence of the grafting density of glycopolymers on the lectin
           binding affinity of block copolymer micelles
    • Authors: Michael Pröhl; Susanne Seupel; Pelin Sungur; Stephanie Höppener; Michael Gottschaldt; Johannes C. Brendel; Ulrich S. Schubert
      Pages: 205 - 212
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Michael Pröhl, Susanne Seupel, Pelin Sungur, Stephanie Höppener, Michael Gottschaldt, Johannes C. Brendel, Ulrich S. Schubert
      The integration of natural carbohydrates as ligands for the targeting of specific cell types into synthetic drug delivery systems such as polymer micelles has gained increasing attention, which is based on the expression of selective receptors or lectins in the cell membrane. While several structural aspects of this interaction are well-understood, only limited knowledge exists on the impact of the grafting density of sugar groups on this interaction. In the presented approach, we created core-shell-corona micelles with comparable size and shape, but a variable density of d-mannosylated chains sticking out from the surface, and investigated their interaction with the lectin concanavalin A (Con A). The polymers were synthesized using the reversible addition fragmentation chain transfer polymerization (RAFT) providing excellent control and narrow distributions for all materials. The blocks based on butyl acrylate and N-acryloyl morpholine form the core and shell of the micelles, respectively, while an additional d-mannosylated block, which forms the corona, is introduced applying a previously reported post-polymerisation functionalization of a reactive bromine precursor with α-d-thiomannose. Varying the ratios of the diblock and triblock polymers in the assembly process, the density of the d-mannosylated chains could easily be adjusted in this mixed micelles approach. All micelles revealed sizes of around 50 nm (estimated by light scattering and cryo-TEM) and similar morphologies, an aspect that is crucial for the direct evaluation of the influence of the grafting density on the binding affinity. The subsequent binding studies with the lectin Con A revealed a clear trend that binding affinity increases with increasing sugar content and a minimum of 10% of d-mannosylated chains is required for an effective and detectible aggregation. However, it is noteworthy that the full coverage of the micelles with sugar chains is detrimental for the binding to Con A and a significant reduction of the clustering rate was observed, while a ligand density of around 50–60% was favorable for the best interaction. These finding substantiate the importance of the ligand density for the design of targeting delivery systems.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.028
      Issue No: Vol. 133 (2017)
       
  • From elastomers to thermoplasts – Precise control of isotactic propylene
           structure and properties and the role of different structural elements in
           its mechanical behaviour
    • Authors: Maxim A. Shcherbina; Marina Yu. Meshchankina; Yaroslav I. Odarchenko; Martin Machat; Bernhard Rieger; Sergey N. Chvalun
      Pages: 213 - 222
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Maxim A. Shcherbina, Marina Yu. Meshchankina, Yaroslav I. Odarchenko, Martin Machat, Bernhard Rieger, Sergey N. Chvalun
      Studies of polypropylene with different degrees of isotacticity have shown a way of the rational design of material with predetermined mechanical properties starting from the synthesis stage already – controlled introducement of stereodefects will allow the smooth adjustment of the Young's modulus and elasticity in the range from plastic to elastomer materials. It was also revealed that modern theoretical models of the elasticity can be successfully applied not only for the description of the mechanical behaviour of polymers, but also for better understanding of the mechanism of elasticity in them. While in the low crystalline materials deformation has Gaussian nature, in the materials of the intermediate crystallinity (30–40%) percolation takes place, and the cross-linking network becomes harder, manifesting the switch to the thermotropic behaviour of the material. Simultaneously the divide between cross- and slip-links becomes substantial, as an extensibility grows sharply.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.11.038
      Issue No: Vol. 133 (2017)
       
  • Overview of polymer nanocomposites: Computer simulation understanding of
           physical properties
    • Authors: Jinbo Zhao; Lili Wu; Chuanxing Zhan; Qian Shao; Zhanhu Guo; Liqun Zhang
      Pages: 272 - 287
      Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133
      Author(s): Jinbo Zhao, Lili Wu, Chuanxing Zhan, Qian Shao, Zhanhu Guo, Liqun Zhang
      Computer simulations are an important implementation to experimental methods working on polymer nanocomposites (PNCs), which have advanced properties because of their unique hierarchy microstructures. In this paper, different computer simulation methods applied to investigate the structures and properties of PNCs and the simulation predicted physical properties of PNCs are reviewed. The fundamentals of applying molecular dynamics simulation method to calculate different physical properties of PNCs are explained accompanied with detailed examples. The results can help to understand the progress on PNC field using simulation methods especially different-sized molecular dynamics simulation methods.
      Graphical abstract image

      PubDate: 2017-12-12T06:24:38Z
      DOI: 10.1016/j.polymer.2017.10.035
      Issue No: Vol. 133 (2017)
       
  • Graphical Contents list &amp; Author index
    • Abstract: Publication date: 20 December 2017
      Source:Polymer, Volume 133


      PubDate: 2017-12-12T06:24:38Z
       
 
 
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