SEPARATION OF POLY(STYRENE-VINYL ACETATE) BLOCK COPOLYMERS BY LIQUID ADSORPTION CHROMATOGRAPHY

Poly(styrene-vinyl acetate) block copolymers, prepared by using a polymeric peroxide as an initiador, were characterized by liquid adsorption chromatography (LAC) and size-exclusion chromatography (SEC). The copolymers were separated according to their chemical composition by LAC using silica gel as an adsorbent and a mixture of 1,2-dichloroethane (DCE) and ethanol as the mobile phase with a 20-min linear gradient from DCEethanol (98:2, v/v) to DCEethanol (85:15, v/v). The column temperature was 30°C. The copolymers were separated by LAC according to the composition in order of increasing vinyl acetate content. The copolymers were fractionated by LAC and SEC in order to determine the relationship between the composition and molecular weight. The LAC fractions were subjected to SEC and the SEC fractions to LAC. The range of composition for the copolymers was between 40 and 90% (w/w) styrene regardless of the monomer feed. There are positive trends in the composition and the molecular weight averages that the copolymer fractions containing more styrene have lower molecular weights, although the copolymers have chemical compositions and molecular weight distributions that are independent of each other. © 1990.