Stereospecific Polymerization of Vinyl Acetate in Fluoroalcohols and Synthesis of Syndiotactic Poly(vinyl alcohol)

The free-radical polymerization of vinyl acetate (VAc) was carried out in various alcoholic solvents in connection with our recent publication in which we reported that the radical polymerization of VAc in (CF3)3COH as a solvent results in a polymer having a high syndiotacticity (r = 72.2%) [K. Yamada, T. Nakano, and Y. Okamoto, Macromolecules, 31, 7598 (1998)]. In this study, (CF3)2CHOH, a fluoroalcohol much less expensive than (CF3)3COH, was found to have an r-enhancing effect similar to (CF3)3COH. The syndiotacticity achieved in this system was up to 70.3% , which is comparable to that during the radical polymerization of vinyl esters in (CF3)3COH. Through the large-scale polymerization using (CF3)2CHOH as a solvent, syndiotactic PVA (r = 69.2%) was obtained for the characterization of its physical properties. It is noteworthy that the polymerization in (CF3)2CHOH at −78°C smoothly proceeded in spite of the fact that the reaction system was apparently solid.