LCST-type phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) in n-butyl acetate

Abstract

Novel polymer solutions exhibiting lower critical solution temperatures (LCSTs) have been studied. An alternating copolymer of 2-chloroethyl vinyl ether and maleic anhydride was synthesized through free-radical solution polymerization. This copolymer can exhibit LCST-type phase behavior in n-butyl acetate (BuAc) under relatively mild conditions at temperatures sufficiently below its boiling point. The effects of molecular weight, polymer concentration and addition of cosolvent on the polymer solution’s cloud point temperature (Tcp) were investigated. The Tcp value was nearly constant over a wide range of concentrations and increased when the polymer concentration was reduced below a certain value. The experimental LCST-type phase diagram can be reasonably described by Flory–Huggins theory. The addition of non-solvents could reduce the Tcp of the polymer solution in BuAc, whereas the addition of good solvents could increase the Tcp. These LCST-type phase behaviors may be attributed to specific polar interactions between the polymer and the solvent.