Yeum, JH Ji, BC Lee, Chul Joo Lee, JY Lee, SS Kim, SS Kim, JH Lyoo, WS 2024-01-21T10:42:54Z 2024-01-21T10:42:54Z 2022-04-05 2002-04 0887-624X https://pubs.kist.re.kr/handle/201004/139612 To prepare water-soluble, syndiotacticity-rich poly(vinyl alcohol) (PVA) microfibrils for various industrial applications, we synthesized syndiotacticity-rich, low molecular weight PVA by the solution polymerization of vinyl pivalate (VPi) in tetrahydrofuran (THF) at low temperatures with 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN) as an initiator and successive saponification of poly(vinyl pivalate) (PVPi). Effects of the initiator and monomer concentrations and the polymerization temperature were investigated in terms of the polymerization behaviors and molecular structures of PVPi and the corresponding syndiotacticity-rich PVA. The polymerization rate of V-Pi in THF was proportional to the 0.91 power of the ADMVN concentration, indicating the heterogeneous nature of THF polymerization. The low-temperature solution polymerization of VPi in THF with ADMVN proved to be successful in obtaining water-soluble PVA with a number-average degree of polymerization (P-n) of 300-900, a syndiotactic dyad content of 60-63%, and an ultimate conversion of VPi into PVPi of over 75%. Despite the low molecular weight of PVA with P-n = 800, water-soluble PVA microfibrillar fibers were prepared because of the high level of syndiotacticity. In contrast, for PVA with P-n = 330, shapeless and globular morphologies were observed, indicating that molecular weight has an important role in the in situ fibrillation of syndiotacticity-rich PVA. (C) 2002 Wiley Periodicals, Inc. English John Wiley & Sons Inc. Preparation of water-soluble, syndiotacticity-rich, low molecular weight poly(vinyl alcohol) microfibrils in high yields with the low-temperature polymerization of vinyl pivalate in tetrahydrofuran and saponification Article 10.1002/pola.10199 1 Journal of Polymer Science, Part A: Polymer Chemistry, v.40, no.8, pp.1103 - 1111 Journal of Polymer Science, Part A: Polymer Chemistry 40 8 1103 1111 N scopus 000174551800020 2-s2.0-0037090134 Polymer Science Polymer Science Article BULK-POLYMERIZATION KINETICS RELEASE syndiotacticity-rich poly(vinyl alcohol) (PVA) low molecular weight solution polymerization vinyl pivalate (VPi) tetrahydrofuran (THF) 2,2 &apos -azobis(2,4-dimethylvaleronitrile) (ADMVN) microfibrillar fibers fibrillation