SEPARATION OF STYRENE-METHYL ACRYLATE COPOLYMER ACCORDING TO CHEMICAL COMPOSITION, USING HIGH-SPEED LIQUID-CHROMATOGRAPHY

It was shown that copolymer samples can be separated according to their chemical compositions by high-speed liquid chromatography (high-speed LC) and also that high-speed LC is hopeful for the rapid and automatic determination of chemical composition distribution (CCD) of copolymers. The chromatograms of a mixture of styrene-methyl acrylate copolymer samples having sharp CCD and different chemical compositions, respectively, were obtained using columns packed with silica gel particles whose micropore size is smaller than about 50 Ǻ by the gradient-elution method with a mixed solvent (CCl4/methyl acetate). The chromatograms showed discrete peaks corresponding to the original components. The apparent CCD of a component was determined from the chromatogram using the respective components as inner standards and compared with the theoretical CCD calculated from copolymerization kinetics. The CCD obtained by using a higher efficiency column was in fairly good agreement with the theoretical one. Moreover, it was shown that the molecular sieve effect is negligible in the present columns. © 1979, American Chemical Society. All rights reserved.