SEPARATION OF STYRENE-BUTYL METHACRYLATE COPOLYMERS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Styrene/n-butyl methacrylate (S/nBMA) and styrene/t-butyl methacrylate (S/tBMA) copolymers were separated by chemical composition using HPLC. In the case of normal phase HPLC using acrylamide gel or acrylonitrile gel as a stationary phase, S/nBMA and S/tBMA copolymers were separated by chemical composition. S/BMA copolymers were eluted from higher styrene content using dichloromethane/n-hexane as an eluent, while with the opposite elution order with tetrahydrofuran/iso-octane eluent, The difference of the elution order is explained by hydrogen bondings between the gel and the sample or eluent. In reversed phase HPLC using a styrene column and nonpolar eluent such as dichloromethane/acetonitrile, S/BMA copolymers were eluted from lower styrene content using any kind of eluent examined. On the other hand, an octadecyl methacrylate column provided no separation based on the composition. The separation using the styrene column was ascribed to the specific interaction of the phenyl groups in the sample and the gel. By the comparison of the content of good solvent in an eluent and clouds point of copolymers, it was confirmed that separation was done by adsorption mechanism for both of normal and reversed phase liquid chromatography.