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  • Physics  (4)
  • Wiley-Blackwell  (4)
  • Public Library of Science
  • Wiley
  • 1
    Electronic Resource
    Electronic Resource
    Free volume and water uptake in a copolymer hydrogel series (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 463-471 
    Details
    ISSN: 0887-6266
    Keywords: hydrogel ; free volume ; positron annihilation ; water ; density ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A copolymer of 2-hydroxyethyl methacrylate (HEMA) with 2-ethoxy ethyl methacrylate (EEMA) was synthesized and the molecular mobility, free volume, and density properties examined as a function of composition. These properties were correlated with the equilibrium water uptake in order to determine which of the properties were most influential in causing high water sorption, as these materials are suitable candidates for hydrogel systems. It was found that the polar HEMA repeat unit results in a rigid, glassy sample at room temperature due to the high degree of hydrogen bonding between chains whereas high EEMA content leads to rubbery samples with subambient glass transition temperatures. The free volume properties on the molecular scale measured by positron annihilation lifetime spectroscopy (PALS) showed that higher HEMA content led to smaller, fewer holes and a lower free volume fraction than EEMA. Therefore the high water uptake of HEEMA-containing copolymers is largely related to the high polarity of the HEMA unit compared to EEMA, despite the low content of free volume into which the water can initially diffuse. Trends in density with copolymer composition, as measured on a macroscopic level, differs to that seen by PALS and indicates that the two techniques are measuring different scales of packing. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 463-471, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    The synthesis of a macromolecular ligand by the modification of polystyrene (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 175-194 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Uncrosslinked atactic polystyrene was chemically modified first by acetylation then by a Claisen condensation with ethyl perfluoropropanoate to produce three crosslinked chelating polymers that contained a phenyl, perfluoroethyl, beta-diketone chelating group in 10, 20, and 63 mole % compositions. Cu(II), Ni(II), and uranyl chelates of the macromolecular ligands were prepared and analyzed. The macromolecular ligands and their chelates were compared with the model ligating species 4,4,5,5,5-pentafluoro-1-phenyl-1,3-pentanedione with infrared and mass spectroscopy and proton nuclear magnetic resonance.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170190117
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  • 3
    Electronic Resource
    Electronic Resource
    Epitaxial crystallization of polymers onto benzoic acid: Polyethylene and paraffins, aliphatic polyesters, and polyamides (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 2495-2509 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Epitaxial crystallization of polyethylene, n-paraffins, aliphatic polyesters, and various polyamides has been achieved on benzoic acid crystal substrates, specifically on their (001) crystals faces, which are made up of the aromatic rings. The epitaxial relationship is very similar for all polymers investigated: it is characterized by a unique chain orientation (parallel to the b axis of the substrate) and a plane of contact which is either the b-c, plane of polyethylene, or crystallographically similar ones for polyesters, or the plane of the hydrogen-bonded sheet for polyamides. Since benzoic acid is structurally similar to its alkali-metal salts, it is inferred that the nucleating efficiency of the latter toward chemically different but structurally similar polymers may well rest on an epitaxial relationship. Finally, the highly oriented morphology made it possible, for some polyesters with a monoclinic cell, to determine the angle between the chain axis and the Z axis of the optical indicatrix, a quantity not measured so far in polymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211207
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  • 4
    Electronic Resource
    Electronic Resource
    A permanganic etchant for polyolefines (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 627-643 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A permanganic etchant has been developed which reveals lamellar and other fine detail in surfaces of at least three crystalline polyolefines, viz., polyethylene (of both high and low density), isotactic polypropylene, and isotactic poly(4-methylpentene-1). In typical treatments of high-density polyethylene ca. 2 μm of material is removed with defective regions suffering preferential attack. The etchant also discriminates between lamellar orientations, eating deeper where side surfaces of laminae are exposed than on fold surfaces, and between different polymers, attacking isotactic polypropylene more strongly than polyethylene. Comparison with other techniques authenticates the detail exposed and samples appear to be otherwise unaltered by their treatment. Besides normal imaging, it is also possible to use etched samples for transmission diffraction studies in the electron microscope. The method has very considerable application for revealing lamellar details in crystalline polyolefines (which can be chosen to be representative or selective according to the nature of the surface used). Examples are given of a wide variety of melt-crystallized morphologies for the three polymers cited and also of lamellae in a drawn polyethylene sample. It is pointed out that permanganic etching is complementary to the technique of chlorosulfonation used to stain polyethylene in a similar way as bright field microscopy is to dark field.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.180170406
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