Bulk polymerization of vinyl pivalate using low-temperature azoinitiator and saponification for the preparation of poly(vinyl alcohol) microfibrils

Won Seok Lyoo, Sung Soo Han, Joan Ho Kim, Won Sik Yoon, Chul Joo Lee, Ick Chan Kwon, Jinwon Lee, Byung Chul Ji, Moon Hee Han

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)

    Abstract

    Vinyl pivalate (VPi) was bulk-polymerized at 30, 40, and 50°C using a low temperature initiator, i.e. 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN). The effects of polymerization temperature and initiator concentration were investigated in terms of polymerization behavior and molecular structures of poly(vinyl pivalate) (PVPi) and corresponding poly(vinyl alcohol) (PVA) microfibrillar fiber obtained by saponification in KOH/methanol/water. Low polymerization temperature using ADMVN proved to be successful in obtaining PVA of syndiotacticity-rich high molecular weight. PVPi had a number-average degree of polymerization (Pn) of 27100-35900, and a degree of branching for pivaloyl group of 0.8-1.0 at 30°C, 1.0-1.3 at 40°C, and 1.4-1.7 at 50°C at conversions below 40%. Saponification of PVPi yielded PVA having a Pn of 10400-16500, and syndiotactic diad (S-diad) content of 58.8-61.5%. It was found that all PVA specimens represented microfibrillar morphologies, with high crystallinity and orientation. The S-diad content and crystal melting temperature were higher with PVA prepared from PVPi polymerized at lower temperatures.

    Original languageEnglish
    Pages (from-to)46-52
    Number of pages7
    JournalAngewandte Makromolekulare Chemie
    Volume271
    DOIs
    Publication statusPublished - 1999 Nov

    ASJC Scopus subject areas

    • General Materials Science

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