Dispersion copolymerization of acrylonitrile-vinyl acetate in supercritical carbon dioxide

Abstract

Dispersion copolymerization of acrylonitrile-vinyl acetate (AN-VAc) had been successfully performed in supercritical carbon dioxide (ScCO2) with 2,2-azobisisobutyronitrile (AIBN) as a initiator and a series of lipophilic/CO2-philic diblock copolymers, such as poly(styrene-r-acrylonitrile)-b-poly(1,1,2,2-tetrahydroperfluorooctyl methacrylate) (PSAN-b-PFOMA), as steric stabilizers. In dispersion copolymerization, poly(acrylonitrile-r-vinyl acetate) (PAVAc) was emulsified in ScCO2 effectively using PSAN-b-PFOMA as a stabilizer. Compared with the precipitation polymerization (absence of stabilizer), the products prepared by dispersion polymerization possessed of higher yield and higher molecular weight. In addition, the particle morphology of precipitation polymerization was irregular, but the particle morphology of dispersion polymerization was uniform spherical particles. In this study, the effects of the initial concentrations of monomer and the stabilizer and the initiator, and the reaction pressure on the yield and the molecular weight and the resulting size and particle morphology of the colloidal particles were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5640–5648, 2006