Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 52 Issue 7

1 April 2014

Volume 52, Issue 7

Pages i–iv, 485–551

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      Cover Image, Volume 52, Issue 7 (pages i–ii)

      Version of Record online: 25 FEB 2014 | DOI: 10.1002/polb.23462

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      The cover shows an atomic force microscopy (AFM) micrograph of the polymer poly(9-(2,3-epoxypropyl)carbazole) (PEPK) doped with 30 wt% core/shell CdSe/ZnS quantum dots (QDs) capped with 16-(N-carbazolyl) hexadecanoic acid, as presented by Adis Khetubol et al. on page 539. In contrast to a matrix of poly(9-vinylcarbazole) (PVK), no clustering of QDs occurs. Combined with stationary and time-resolved spectroscopic data, this suggests that the enhanced singlet and triplet energy transfer from the matrix to the blue-emitting QDs in PEPK is due to a combination of the decreased excimer formation and the improved miscibility.

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      Cover Image, Volume 52, Issue 7 (pages iii–iv)

      Version of Record online: 25 FEB 2014 | DOI: 10.1002/polb.23466

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      Solution-state thermal properties of the poly(ethylene oxide-b-NIPAAm) copolymer with a C12 end-cap can be modified via the addition of salts at concentrations as low as 1 mM, as shown by Ian M. Henderson et al. on page 507. The aggregation temperature can be slightly raised or lowered, depending on the position of the salt in the Hoffmeister series. In addition to aggregation temperature changes, evidence of thermohysteresis is found upon the addition of salts to samples that are repeatedly thermally cycled. The concentration of the polymer, the presence of acids, and the C12 end group are also demonstrated to be methods by which the thermal behavior can be modified.

  2. Full Papers

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    3. Full Papers
    1. Investigation on the mechanical behavior of poly(2-hydroxyethyl methacrylate) hydrogel membrane under compression in the assembly process of microfluidic system (pages 485–495)

      Weiwei Zhao, Changqing Liu, Fengshun Wu and Cristina Lenardi

      Version of Record online: 8 FEB 2014 | DOI: 10.1002/polb.23449

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      The mechanical characteristics of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel membranes, which are used in the assembly of microfluidic systems, are investigated using experiments and simulation. The results demonstrate the feasibility of the assembly of microfluidic systems using a mechanical fastening technique, and also provide guidelines for the optimum design of microchannels in the assembly process through mechanical fastening.

    2. Process influences on the structure, piezoelectric, and gas-barrier properties of PVDF-TrFE copolymer (pages 496–506)

      Fabiane Oliveira, Yves Leterrier, Jan-Anders Månson, Olha Sereda, Antonia Neels, Alex Dommann and Dragan Damjanovic

      Version of Record online: 9 JAN 2014 | DOI: 10.1002/polb.23443

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      A 10-fold decrease of O2 permeability of polyvinylidene fluoride trifluoroethylene copolymer films occurs upon annealing between the Curie temperature and the melting point of the polymer. Additionally, annealing increases the piezoelectric coefficient of the films. These changes are controlled by a crystalline phase transition, from the paraelectric α-phase to the ferroelectric β-phase. These combined gas barrier and piezoelectric properties are key to increasing the sensitivity of piezoelectric gas-barrier liners for high-pressure storage vessels.

    3. Ionic effects on the behavior of thermoresponsive PEO–PNIPAAm block copolymers (pages 507–516)

      Ian M. Henderson, Peter G. Adams, Gabriel A. Montaño and Walter F. Paxton

      Version of Record online: 9 JAN 2014 | DOI: 10.1002/polb.23444

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      The environment of thermoresponsive block copolymers—particularly in solutions with even modest electrolyte concentrations (1–10 mM)—can have a profound effect on transition temperatures and morphology. Salt solutions affect the critical aggregation temperature of the poly(ethylene oxide-b-N-isopropylacrylamide) copolymer with a C12 end-cap; the kosmotropic adipic ion lowers the critical aggregation temperature, and the chaotropic iodide raises it. It is found that thermohysteretic behavior is possible in the presence of salts, with some fraction of the aggregate remaining after being thermally cycled.

    4. Thermal behavior of poly(vinylbenzyl chloride)-grafted poly(ethylene-co-tetrafluoroethylene) films (pages 517–525)

      Ju-Myung Song, Sun-Young Lee, Hyun-Su Woo, Joon-Yong Sohn and Junhwa Shin

      Version of Record online: 20 JAN 2014 | DOI: 10.1002/polb.23445

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      Radiation grafting is considered to be an effective way of modifying a polymer, and properties of the polymeric material can be easily modified by controlling irradiation conditions. Here, effects of the degree of grafting on the thermal behavior of poly(vinylbenzyl chloride)-grafted-poly(ethylene-co-tetrafluoroethylene) films are investigated. The activation energy of the polymer is increased with an increase in the degree of grafting, indicating an increase in the crosslinking of the films.

    5. Poly(3-hexylthiophene) aggregate formation in binary solvent mixtures: An excitonic coupling analysis (pages 526–538)

      Calynn E. Johnson and David S. Boucher

      Version of Record online: 3 FEB 2014 | DOI: 10.1002/polb.23447

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      Solvent quality is well known to affect the formation of solution-phase poly-(3-hexylthiophene) (P3HT) aggregates. This study uses 96 different binary solvent systems to induce the assembly of P3HT, and the resulting aggregates display a wide range of structural order, which is probed by UV–vis absorption spectroscopy. A Spano excitonic coupling analysis and Hansen solubility parameters are used to reveal correlations between the properties of the solvents and the extent of order within the aggregates.

    6. Triplet harvesting in poly(9-vinylcarbazole) and poly(9-(2,3-epoxypropyl)carbazole) doped with CdSe/ZnS quantum dots encapsulated with 16-(N-carbazolyl) hexadecanoic acid ligands (pages 539–551)

      Adis Khetubol, Sven Van Snick, Egle Stanislovaityte, Antti Hassinen, Eduardo Coutiño-González, Willem Vanderlinden, Yuliar Firdaus, Eduard Fron, Maarten Vlasselaer, Jurate Simokaitiene, Steven De Feyter, Zeger Hens, Juozas V. Grazulevicius, Wim Dehaen and Mark Van der Auweraer

      Version of Record online: 12 FEB 2014 | DOI: 10.1002/polb.23451

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      To enhance the efficiency of polymer light-emitting diodes, the polymer is often doped with a triplet emitter. In order to obtain a blue-emitting material, PVK and PEPK are chosen as fluorescent polymer matrices for blue-emitting CdSe/ZnS quantum dots (QDs), encapsulated with a carbazole-terminated ligand. The better miscibility and less extensive excimer formation enhance the efficiency of both singlet and triplet energy transfers to the QDs significantly in PEPK compared to PVK.