Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 49 Issue 19

1 October 2011

Volume 49, Issue 19

Pages i–ii, 1347–1419

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      Cover Image, Volume 49, Issue 19 (pages i–ii)

      Article first published online: 29 AUG 2011 | DOI: 10.1002/polb.22358

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      On page 1397 of this issue, R. M. Michell, A. J. Müller, and colleagues present AFM height images revealing the morphology of stereocomplexes formed from solution mixtures of amphiphilic poly(d-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLA-b-PDMAEMA) and poly(l-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PLLA-b-PDMAEMA) copolymers. The PDLA and PLLA blocks can co-crystallize, resulting in the peculiar observed morphologies. The morphology can be tuned by varying the composition of the diblock copolymers or by mixing the appropriate homo-PLA with one of the copolymers. The PDMAEMA block influences the stability of the stereocomplex structures.

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    1. Annealing of melt-crystallized polyethylene and its influence on microstructure and mechanical properties: A comparative study on branched and linear polyethylenes (pages 1347–1359)

      Shijie Song, Jiachun Feng and Peiyi Wu

      Article first published online: 18 JUL 2011 | DOI: 10.1002/polb.22304

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      Annealing-induced structural changes on lamellar scale are extremely important for semicrystalline polymers both in fundamental research and industrial applications. For branched polyethylene, the influence of annealing on lamellar rearrangement is found to be more versatile when compared with its linear counterpart. The evolution of the lamellar-scaled crystalline structure can be used to interpret the heat distortion temperature property variation from the aspects of both the crystalline elasticity and the degree of lamellar relaxation.

    2. In situ synthesis of ZnO nanocrystal/PET hybrid nanofibers via electrospinning (pages 1360–1368)

      Junhua Zhang, Bin Wen, Feng Wang, Yanfen Ding, Shimin Zhang and Mingshu Yang

      Article first published online: 18 JUL 2011 | DOI: 10.1002/polb.22306

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      The use of ZnO/polymer hybrid materials as sensors and catalysts is strongly limited by the difficulty of gases to penetrate into the bulk of the nanocomposites. This limitation is overcome by preparing nanofibers with large surface-area-to-volume ratio and the ZnO particles located mainly on the surface of the fibers via electrospinning combined with a sol-gel method. These nanofibers show intense UV emission and found application in light emitting devices, solar cells, and sensors.

    3. Molten polystyrene structures above the glass transition, T > Tg (pages 1369–1380)

      L. A. Utracki and P. Sammut

      Article first published online: 18 JUL 2011 | DOI: 10.1002/polb.22313

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      True liquids exist above the crossover temperature Tc. Cooling creates solid aggregates with the percolation threshold at glass temperature, that is, the solid domains exist below and above Tg. Results from high-pressure dilatometry and oscillatory shear tests in the glassy and the molten state of polystyrenes indicates that such nonequilibrium, variable structures depend on the morphology of the vitreous polymer and the annealing rate across Tg.

    4. Nonisothermal crystallization kinetics of in situ nylon 6/graphene composites by differential scanning calorimetry (pages 1381–1388)

      Fan Zhang, Xiaochun Peng, Wenbin Yan, Zhiyuan Peng and Yongqiang Shen

      Article first published online: 3 AUG 2011 | DOI: 10.1002/polb.22321

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      Polymer/graphene nanocomposites display much better mechanical, thermal, and electrical properties when compared to pure polymer. Here, the effect of graphene on the crystallization behavior and kinetics of the nylon 6/graphene was studied. The results were analyzed based on the Avrami theory modified by Jeziorny, and the linearity of the plots indicated that the approach successfully describes the crystallization processes of both pure polymer and composites. The activation energies of the composites were lower than those of pure nylon.

    5. Synthesis and characterization of water-dispersible, superparamagnetic single-wall carbon nanotubes decorated with iron oxide nanoparticles and well-defined chelating diblock copolymers (pages 1389–1396)

      Petri Papaphilippou, Rodica Turcu and Theodora Krasia-Christoforou

      Article first published online: 3 AUG 2011 | DOI: 10.1002/polb.22322

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      A new approach for the fabrication of magneto-active carbon nanotubes stabilized in aqueous media is described here, where a well-defined methacrylic diblock copolymer is combined with carboxylated single-wall carbon nanotubes and iron oxide nanoparticles. The resulting nanocomposites exhibit superparamagnetic behavior at room temperature.

    6. Crystallization and stereocomplexation behavior of poly(D- and L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) block copolymers (pages 1397–1409)

      Rose Mary Michell, Alejandro J. Müller, Mariya Spasova, Philippe Dubois, Stefano Burattini, Barnaby W. Greenland, Ian W. Hamley, Daniel Hermida-Merino, Nicolas Cheval and Amir Fahmi

      Article first published online: 3 AUG 2011 | DOI: 10.1002/polb.22323

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      The crystallization, morphology, and stereocomplexation of amphiphilic poly(D-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLA-b-PDMAEMA) and poly(L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PLLA-b-PDMAEMA) copolymers were studied and compared to those of the corresponding poly(lactide) homopolymers. The crystallization kinetics of the PLA blocks was retarded by the presence of the PDMAEMA block. The melting points of PLDA/PLLA and PLA/PLA-b-PDMAEMA stereocomplexes were higher than those formed by copolymer mixtures indicating that the PDMAEMA block is influencing the stability of the stereocomplex structures.

    7. Donor–acceptor diethynylsilane oligomers: A second-order nonlinear optical material (pages 1410–1419)

      Ana E. De A. Machado, Leonardo A. De Souza, Hélio F. Dos Santos and Wagner B. De Almeida

      Article first published online: 9 AUG 2011 | DOI: 10.1002/polb.22324

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      The search for molecules possessing a large value of first hyperpolarizability (β) is a key step toward the optimization of new materials for nonlinear optical response applications. By using density functional theory to screen suitable materials, it is suggested that disubstituted diethynylsilane decamers should have great potential as building blocks for molecular-based materials with a second-order nonlinear response.

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