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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 3597-3620 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Open-bath, organic liquid treatments may be used to produce high surface area PET fibers through the action of liquid solvent-induced crystallization (SINC). It has been found that as the treatment bath temperature is increased, surface modification suddenly disappears. For a particular treatment method this occurs at a reproducible temperature, well below the liquid boiling point. A qualitative understanding of the mechanism of surface cavitation during liquid SINC is developed based on current descriptions of the component processes involved. These processes are: the glass-rubber transition, diffusion through rubbery and glassy polymer, and polymer-diluent crystallization. Although calculations of the threshold concentration for swelling support this conceptual framework, the absence of surface cavitation at higher treatment bath temperatures is not explained by it and is therefore attributed to an intervening phenomenon. Analysis of penetration depth data together with surface microscopy suggest the formation of a smooth surface layer interfering with normally observed cavitation at elevated temperatures. Manipulation of the extent of vapor precontact shows that vapor SINC prior to liquid exposure is most likely responsible for the smooth layer.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The design of biomaterials containing specific ligands on the surface offers the possibility of creating materials that can interact with and potentially control mammalian cell behavior. Biodegradable materials further provide the significant advantage that the polymer will disappear in vivo, obviating long-term negative tissue responses as well as the need for retrieval. In earlier studies we synthesized and characterized arginine - glycine - aspartic acid (RGD) peptide-modified poly(lactic acid-co-lysine) (PLAL). In this study, both bulk properties and surface features have been characterized, with a focus on surface analysis as a means of interpreting observed changes in cell behavior. Bulk peptide attachments were performed using 1,1′-carbonyldiimidazole (CDI). Amino groups were measured using colorimetric assays and X-ray photoelectron spectroscopy (XPS). Peptides were measured by incorporating iodine into the peptide as a distinct elemental marker for use with XPS. Typical samples contained 13 ± 4 pmol/cm2 of amino groups and 4 ± 0.2 pmol/cm2 of peptides, as calculated from XPS measurements of nitrogen and iodine. The wettability and crystallinity of the samples were determined by contact angles and differential scanning calorimetry, respectively. Wettability and crystallinity were not altered by the incorporation of lysine or peptides. After incubating bovine aortic endothelial (BAE) cells for 4 h on surfaces with RGD-containing peptides, the mean spread cell area increased from 77 ± 2 μm2 to 405 ± 29 μm2 compared to 116 ± 11 μm2 on poly(lactic acid), 87 ± 4 μm2 on PLAL, and 105 ± 4 μm2 on surfaces with RDG-containing (control) peptides. The significance of this work is that the first synthetic interactive, resorbable biomaterial has been developed, and use of this material to control cell behavior has been demonstrated. © 1997 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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