Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 51 Issue 15

1 August 2013

Volume 51, Issue 15

Pages i–ii, 1125–1193

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      Cover Image, Volume 51, Issue 15 (pages i–ii)

      Version of Record online: 18 JUN 2013 | DOI: 10.1002/polb.23333

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      The structure and crystallinity of polyelectrolytes has long been known to affect their ionic conductivity, but the effects of water of hydration on polyelectrolyte structure are not commonly studied. On page 1162, Yujun Yang and Hong Huo show that the structure of the complex formed in PEO/anhydrous MgCl2 is significantly different to that of the complexes formed in PEO/hydrated MgCl2, indicating that the “crystal water” of the metal salts strongly affects the complex structure in polymer electrolytes. The cover displays a room-temperature polarized optical microscopy image of a (PEO)9MgCl2·4H2O complex, with both inner and outer PEO spherulites. The finer outer spherulite grows radically along the dark inner spherulite and the birefringence turns bright.

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    1. Strain induced nanocavitation and crystallization in natural rubber probed by real time small and wide angle X-ray scattering (pages 1125–1138)

      Huan Zhang, Arthur K. Scholz, Yannick Merckel, Mathias Brieu, Daniel Berghezan, Edward J. Kramer and Costantino Creton

      Version of Record online: 21 MAY 2013 | DOI: 10.1002/polb.23313

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      The concomitant appearance of crystallites and nanocavities under uniaxial strain is investigated by X-ray scattering in filled natural rubber. 20–50 nm elliptical nanocavities appear after crystallization and only when the true stress is above a critical cavitation stress σCav. The clear correlation between σCav and degree of crystallinity at the onset of cavitation χCry(λCav) implies that the crystallites take most of the mechanical loading thus delaying the cavitation in the amorphous phase.

    2. Viscoelastic phase diagram of fluorinated and grafted polymer films and proton-exchange membranes for fuel cell applications (pages 1139–1148)

      Yves Leterrier, Jérémy Thivolle, Fabiane Oliveira, Jan-Anders Månson, Lorenz Gubler, Hicham Ben youcef, Lukas Bonorand and Günther Scherer

      Version of Record online: 21 MAY 2013 | DOI: 10.1002/polb.23309

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      Proton exchange membranes for fuel cell applications were developed based on fluorinated, radiation grafted, and crosslinked polymers. These polymers exhibit intricate hygro-thermo-mechanical properties. A phase diagram was developed to map critical transitions in viscoelastic behavior and to investigate the influence of the grafted and crosslinked chemistry on these transitions. A deeper understanding of the stability of such membranes under different conditions should facilitate the construction of more robust fuel cells.

    3. Use of polystyrene brushes to investigate the role of interface between substrates and thin homogeneous films (pages 1149–1156)

      Franco Dinelli, Tommaso Sgrilli, Andrea Ricci, Paolo Baschieri, Pasqualantonio Pingue, Manjunath Puttaswamy and Peter Kingshott

      Version of Record online: 16 MAY 2013 | DOI: 10.1002/polb.23310

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      The temperature dependence of the viscoelastic properties of thin polystyrene (PS) films is monitored via the indentation of an atomic force microscope tip into films prepared on native silicon oxide, H-terminated silicon, and PS brushes. For film/brush combinations with Mw above the critical value for the occurrence of molecular entanglement or for films with the same Mw values on H-terminated silicon, the Tg of thin films becomes comparable with the bulk value. Data are discussed in terms of residual solvent presence, interfacial free volume, and molecular entanglement.

    4. Positron lifetime spectroscopy in ordered nanoporous polymers (pages 1157–1161)

      Jason Engbrecht, David Green, Marc A. Hillmyer, David Olson and Eric M. Todd

      Version of Record online: 5 JUN 2013 | DOI: 10.1002/polb.23314

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      Positron lifetime spectroscopy is extended to analyze the pore structure of nanoporous polymers prepared from ordered triblock polymer precursors.

    5. Investigation of structures of PEO-MgCl2 based solid polymer electrolytes (pages 1162–1174)

      Yujun Yang and Hong Huo

      Version of Record online: 22 MAY 2013 | DOI: 10.1002/polb.23315

      Thumbnail image of graphical abstract

      The structure and crystallinity of polyelectrolytes has long been known to affect their ionic conductivity, but the effects of water of hydration on polyelectrolyte structure are not commonly studied. Here, the structure of the complex formed in PEO/anhydrous MgCl2 is shown to be significantly different to those of the complexes formed in PEO/hydrated MgCl2, indicating the “crystal water” of the metal salts strongly affects the complex structure in polymer electrolytes.

    6. Influence of multiple stimuli on the lower critical solution temperature of new cationic poly(N-acryloyl-N′-ethylpiperazine-co-N-isopropylacrylamide) solutions (pages 1175–1183)

      G. Roshan Deen, Quah Li Zhen, Mah Chin Hao and Xian Jun Loh

      Version of Record online: 29 MAY 2013 | DOI: 10.1002/polb.23316

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      A new cationic polymer, poly(N-acryloyl-N'-ethylpiperazine-co-N-isopropylacrylamide), is reported to be sensitive to multiple external stimuli such as changes in pH, temperature, salt, and surfactants. The polymer exhibited a sharp and well-defined lower critical solution temperature (LCST) because of its coil-to-globule transition. Polymerization behavior and the influence of multiple stimuli on the LCST of polymer solutions are studied in detail. This understanding could be used to tune the polymer's behavior for applications such as controlled gene delivery.

    7. Gas barrier behavior of polyimide films filled with synthetic chrysotile nanotubes (pages 1184–1193)

      Yingji Wu, Vladimir E. Yudin, Joshua U. Otaigbe, Elena N. Korytkova and Sergei Nazarenko

      Version of Record online: 5 JUN 2013 | DOI: 10.1002/polb.23317

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      Chrysotile nanotubes (ChNTs) containing polyimide nanocomposites were prepared by a solution mixing/casting method. The nanotubes were nanodispersed and oriented in the plane of the film in the nanocomposites with up to 4.5% (vol/vol) of ChNTs leading to a gradual increase of the gas barrier. The lowest gas permeability was 60% smaller than that for the pristine polyimide film. However, with the onset of nanotube micro-aggregation at larger ChNT loadings the nanotube dispersion and orientation were compromised and oxygen barrier was reduced. The efficacy of nanotubes to enhance the polymer gas barrier was discussed and compared with that of nanoplatelets.

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