Characterizations of poly(vinyl pivalate) polymerized in tertiary butyl alcohol and resulting syndiotactic poly(vinyl alcohol) microfibrils saponified

Vinyl pivalate (VPi) was solution-polymerized in tertiary butyl alcohol (TB A) and in dimethyl sulfoxide (DMSO) with low chain transfer constant using a low temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN) . TEA was absolutely superior to DMSO in increasing the syndiotacticity and molecular weight of poly(vinyl alcohol) (PVA). Low-temperature solution po lymerization of VPi in TEA or DMSO by adopting ADMVN proved to be successfu l in obtaining PVA of ultrahigh molecular weight (maximum number-average de gree of polymerization (P-n): 13,500-17,000) and of high yield (ultimate co nversion of VPi into PVPi: 55-80%) to a much higher conversion than that fr om bulk polymerization. Moreover, PVA from TEA system were fibrous, with a high degree of orientation of the crystallites, indicating the syndiotactic nature of TEA polymerization. (C) 2001 Published by Elsevier Science Ltd.