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

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 ( T cp ) were investigated. The T cp 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 T cp of the polymer solution in BuAc, whereas the addition of good solvents could increase the T cp . These LCST-type phase behaviors may be attributed to specific polar interactions between the polymer and the solvent. Poly(2-chloroethyl vinyl ether- alt -maleic anhydride) can exhibit thermoreversible phase behavior of lower critical solution temperature in n -butyl acetate at mild temperatures below boiling point of solvent. Cloud point of polymer solution can be tuned in a wide range of temperature conveniently. Effect of polymer concentration and addition of cosolvent on cloud point of polymer solution was investigated and the lower critical solution temperature-type phase behavior of polymer solution was analyzed in lattice theory.