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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 673-679 
    ISSN: 0887-6266
    Keywords: scanning force microscopy ; hectorite ; polystyrene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Many important layered silicate-polymer nanocomposite materials may be synthesized using an in-situ polymerization process. Using this technique, organic monomers are intercalated into the interlayer regions of the hosts, where subsequent polymerization may then occur. In this paper, we report on the in-situ polymerization of styrene in Cu(II)-exchanged hectorite thin films. Scanning force microscopy (SFM) images of the polymer surface reveal that the surface polystyrene is generally aggregated into groups of elongated strands. SFM imaging of the interclay regions, in conjunction with X-ray diffraction (XRD) and electron spin resonance (ESR) data, indicates that approximately 20-30% of these regions contain polystyrene, with minimal reduction in the majority of Cu2+ sites observed. XRD data shows little or no intercalation of the monomer into the true intergallery regions. Instead, the polymer likely forms in intercrystallite or planar defect regions. In addition, two distinct phases of polymeric material are found within these defect regions, a highly polymerized polystyrene in addition to a polystyrene form exhibiting greater material stiffness. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 673-679, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2167-2173 
    ISSN: 0887-6266
    Keywords: scanning force microscopy ; electric conductivity ; polyaniline ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The technique of scanning force microscopy was used to study the nanometer-scale structure of NMP cast films of polyaniline. Noncontact mode images provide direct evidence that polyaniline prepared in this form is a granular conductor. The films were found to consist of micrograins whose size and density were determined by the pH of the acid solution used to protonate the films. At pH 7, the polyaniline films exhibited a mostly disordered structure, with small 2-10 nm particles visible. Protonation at pH 5 to pH 3 resulted in partial agglomeration of the primary particles into larger bundles, with sizes up to 75 nm. Treatment in solution pHs of 2 or less resulted in films consisting of close-packed bundles of dimension 20-30 nm. The conductivity of the films exhibited a sharp rise beginning with protonation at pH 2 or less. Effective medium theory (EMT), was used to model the macroscopic conductivity of these films based on the SPM measured microscopic film structure. Using the size and size distribution of polymer micrograins or bundles in a modified EMT, we are able to obtain predicted conductivities that are close to the measured values for these films. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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