Journal of Polymer Science Part B: Polymer Physics

Cover image for Vol. 50 Issue 4

15 February 2012

Volume 50, Issue 4

Pages i–ii, 229–304

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Reviews
    4. Full Papers
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      Cover Image, Volume 50, Issue 4 (pages i–ii)

      Article first published online: 4 JAN 2012 | DOI: 10.1002/polb.23034

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      Silk fibroin derived from silkworm cocoons is finding increasing use in regenerative medicine and bio-sensing. Several methods for tailoring the material to specific uses currently exist, including electrospinning and electrogelation. On page 257, Mark Cronin-Golomb and colleagues demonstrate the ability to use light as an additional means of silk engineering thereby widening the range of applications to include optical sensing, optical information storage, and optical tuning of tissue engineering scaffolds. The optical sensitivity made possible by azo modification of the silk has high enough spatial resolution to enable holographic recording. The cover image shows reconstruction of a holographic image recorded in a thin film of azo modified silk fibroin. The curved lines around the image result from refraction through the wavy piece of silk that was used in the experiment. Azo-modified silk retains biocompatibility and may be suitable for use in implantable optical sensors and optically patterned substrates for tissue engineering.

  2. Reviews

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      Theoretical consideration and modeling of self-healing polymers (pages 229–241)

      Ming Qiu Zhang and Min Zhi Rong

      Article first published online: 31 OCT 2011 | DOI: 10.1002/polb.22387

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      Inspired by the ability of naturally occurring species in autonomic healing of nonfatal harm, the concept of self-repair has now been transferred to the design and manufacturing of a brand new category of materials: self-healing polymers. To understand the mechanisms involved and to develop novel healing strategy, theorists have conducted researches in different aspects. This review systematically summarizes and discusses the progresses on microscopic and macroscopic scales.

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Reviews
    4. Full Papers
    1. Fabrication of 3D electrospun structures from poly(lactide-co-glycolide acid)–nano-hydroxyapatite composites (pages 242–249)

      Linus H. Leung, Stephanie Fan and Hani E. Naguib

      Article first published online: 6 DEC 2011 | DOI: 10.1002/polb.22396

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      Electrospinning has been widely used to fabricate nanofibrous meshes for various applications, but these meshes are usually limited to two-dimensional (2D) structures. A novel fabrication technique was developed for creating 3D, micropatterned, electrospun structures. This technique, used here to make a nanocomposite material of poly(lactide-co-glycolide acid) and hydroxyapatite, uses pressurized gas to sinter 2D meshes together in a stack, overcoming the challenges of depositing a thick, 3D structure. These thick meshes are ideal for tissue engineering scaffolds.

    2. Characterization of phase separation of polystyrene/poly(vinyl methyl ether) blends using fluorescence (pages 250–256)

      Annika Kriisa, Sung S. Park and Connie B. Roth

      Article first published online: 19 NOV 2011 | DOI: 10.1002/polb.23000

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      Understanding how chemical structure affects specific interactions in polymer blends is important in developing blending models that can predict miscibility and blend properties from their individual constituents. Here, the fluorescence emission spectra of various aromatic fluorophores covalently bonded to polystyrene during phase separation from poly(vinyl methyl ether), a prototypical miscible blend, are investigated. The sharp increase in fluorescence intensity upon phase separation, associated with removal of fluorescence quenching, is believed to result from a weak hydrogen bond.

    3. Optically induced birefringence and holography in silk (pages 257–262)

      Mark Cronin-Golomb, Amanda R. Murphy, Jessica P. Mondia, David L. Kaplan and Fiorenzo G. Omenetto

      Article first published online: 19 NOV 2011 | DOI: 10.1002/polb.23003

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      Silk fibroin from Bombyx mori caterpillars is finding increasing use as a biocompatible polymer for use in tissue engineering and biosensing. Diazonium coupling offers one route to functionalization of the polymer to tailor its interactions with its surroundings. This process results in the appearance of optical sensitivity as evidenced by the appearance of optically induced birefringence and holography. This polarizing microscope image of a thin film of azo-modified silk shows birefringence on the left induced by laser light at 488 nm.

    4. Manipulating morphology and orientation in thermally responsive block copolymer thin films (pages 263–271)

      Jennifer Y. Kelly, Julie N. L. Albert, John A. Howarter, Christopher M. Stafford, Thomas H. Epps III and Michael J. Fasolka

      Article first published online: 4 DEC 2011 | DOI: 10.1002/polb.23004

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      Block copolymers spontaneously self-assemble into a variety of structures, but can also be manipulated using processing methods. Here, various annealing steps are used to obtain different morphologies and orientations in thermally responsive block copolymer thin films. The protocols that combine equal numbers of solvent vapor annealing and thermal annealing steps are not necessarily equivalent, and the order of the solvent annealing relative to thermal annealing is a deciding factor in the final morphology.

    5. Properties of single-walled carbon nanotube-based poly(phenylene vinylene) electroluminescent nanocomposites (pages 272–279)

      Mansour K. AbdulBaki, Andrew Tangonan, Rigoberto C. Advincula, T. Randall Lee and Ramanan Krishnamoorti

      Article first published online: 29 NOV 2011 | DOI: 10.1002/polb.23007

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      Poly(p-phenylene vinylene)s (PPVs) are conducting polymers popular for their electrical conductivity and electroluminescence properties that can be tailored by side-chain functionalization. Incorporation of single-walled carbon nanotubes (SWNTs) leads to a significant enhancement in device performance. The current and electroluminescent turn-on voltages with respect to SWNT loading show that turn-on voltage decreases with SWNT addition. However, reduced electroluminescent intensity indicates that there is an upper bound to the benefits of adding SWNTs to organic-based LEDs.

    6. White light electroluminescence from graphene-enhanced single polymer comprising two color emitters of equal molar ratios (pages 280–288)

      Reagen Ying-Tai Su, Li-Ko Chiu, Shan-Wei Weng, Ying-Shiun Chou and Raymond Chien-Chao Tsiang

      Article first published online: 29 NOV 2011 | DOI: 10.1002/polb.23008

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      Conjugated polymers have been studied for their potential low-cost applications in making polymeric light-emitting diodes. In this article, a white polymeric light-emitting diode is fabricated from an alternating copolymer—poly(3-hexylthiophene-alt-9,9-dioctylfluorene) (PTAF)—made up of 50% blue-green light-emitting fluorene and 50% red-orange light-emitting 3-hexylthiophene. Blending with graphene results in an increase in conductivity as well as a higher luminescence than the device fabricated with pure PTAF. The TEM image shows intertwined PTAF and graphene.

    7. Dielectric studies of tetraaryl and triaryl polycarbonates and comparisons with bisphenol A-polycarbonate (pages 289–304)

      J. J. Fontanella, D. A. Boyles, T. S. Filipova, S. Awwad, C. A. Edmondson, J. T. Bendler, M. C. Wintersgill, J. F. Lomax and M. J. Schroeder

      Article first published online: 6 DEC 2011 | DOI: 10.1002/polb.23010

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      High strength and toughness, broad temperature resistance, and optical-quality transparency make bisphenol A-polycarbonate (BPA-PC) useful in a wide range of commercial industries including capacitor applications. Dielectric relaxation is used to study molecular motions in BPA-PC and then to compare these motions with those found in two new high-temperature polycarbonates with small cross-sectional areas, small packing lengths, and low entanglement weights. The results shed light on discrepancies that exist in the literature for BPA-PC.

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