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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1395-1405 
    ISSN: 0887-624X
    Keywords: polyanhydride ; oxepan-2,7-dione ; ring-opening polymerization ; crosslinking ; degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinked poly(adipic anhydride) has been obtained in this study of the synthesis of a rapidly hydrolyzable crosslinked polymer system. The thermal, mechanical, and degradative behavior was markedly affected by the ratio of reactants, using 0-50 mol % of the crosslinking agent. Optimum properties were reached at 20-30 mol %. Methylene segment crosslinks were obtained by copolymerizing oxepan-2,7-dione (adipic anhydride) with 1,2,7,8-diepoxy-octane. The crosslinking reaction resulted in polyester bonds but the material had a significant amount of poly(adipic anhydride) homosequences. These are crucial for a rapid degradation. The network formation is dependent on the functionality of the reactants, on the reactivities of the functional groups and on the reaction pathways. In this study, the most important factor affecting the structure of main chains is the higher reactivity of the anhydride compared to that of the epoxide leading to homopolymer sequences. This was also evident in the model reaction between oxepan-2,7-dione and 1,2-epoxybutane. The initial degradation profile of the crosslinked polymer corresponds to the linear counterpart of the polymer. The remaining polyester network has a longer degradation rate. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1635-1649 
    ISSN: 0887-624X
    Keywords: poly(1,5-dioxepan-2-one) ; crosslinking ; bis(∊-caprolactone) ; swelling behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(lactones) may be crosslinked by ring-opening polymerization of the corresponding cyclic esters in the presence of tetrafunctional bis(∊-caprolactone). The homopolymer of 1.5-dioxepan-2-one (DXO) has poor mechanical properties but also some very good properties, such as biocompatibility and degradability. Crosslinking of degradable polymer based on the poly(ether-ester) DXO was performed with crosslinkers having the same reactivity as the monomer. 2,2-Bis(∊-caprolactone-4-yl)propane (BCP) and bis(∊-caprolactone-4-yl) (BCY) with tetrafunctionalities were synthesized from the corresponding diols and then used as comonomers during the polymerization of DXO. The comonomers showed the same reactivity to the initiator, stanneous 2-ethylhexanoic acid, as DXO and perfectly random crosslinked films were obtained. The crosslinked films showed a high degree of swelling already at 2-3 mol % BCP or BCY. The BCP crosslinker was somewhat less soluble in DXO at lower temperatures, but all BCP was soluble at 180°C. These polymeric films were elastic with no crystallinity and the Tg values increased from -39°C for pure DXO to -35°C for BCP crosslinked films and -21°C for BCY crosslinked ones. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1635-1649, 1997
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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