Characterization and Physical Properties of Low Molecular Weight Poly(vinyl acetate) and Poly(vinyl alcohol)

Abstract

Low molecular weight poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA) having a 2-hydroxyethylthio group at one end were synthesized using 2-mercaptoethanol as a chain transfer agent. The dependence of physical properties of PVAc and PVA on the degree of polymerization was investigated. It became clear that vapor pressure osmometry was useful as well as 1H NMR analysis to determine the number average degree of polymerization of the low molecular weight PVAc and PVA. The glass transition temperature of the PVAc decreased below 150 as the number average degree of polymerization (Pn), and the melting temperature and degree of crystallinity of the PVA had no or little change above around 100 of Pn, but changed below 100, estpcially at less than 50. The effect of chemical structure of the end groups on the swelling was also studied.