Synthesis of water-soluble syndiotacticity-rich low molecular weight poly(vinyl alcohol) by solution copolymerization of vinyl pivalate/vinyl acetate in tetrahydrofuran and saponification

摘要

Syndiotacticity-rich low molecular weight poly(vinyl alcohol) (PVA) was synthesized by solution co-polymerization of vinyl pivalate (VPi) and vinyl acetate (VAc) in tetra hydrofuran (THF) at low temperature using 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN) as an initiator and successive saponification of copoly(VPi/VAc). Effects of initiator and monomer concentrations and polymerization temperature on the polymerization behavior and molecular structure of PVA prepared were investigated. The polymerization rate of VPi and VAc in THF was proportional to the 0.96 power of ADMVN concentration, indicating the heterogeneous nature of THE polymerization. Low temperature solution copolymerization of VPi and VAc in THF by adopting ADMVN proved to be successful in obtaining water-soluble PVA with number-average degree of polymerization of 180-360, syndiotactic diad content of 56-58%, and ultimate conversion of VPi and VAc into copoly(VPi/VAc) of over 80%, respectively. (C) 2003 Wiley Periodicals, Inc. [References: 21]