DETERMINATION OF THE CHEMICAL-COMPOSITION DISTRIBUTION OF COPOLYMERS OF STYRENE AND BUTADIENE BY GRADIENT POLYMER ELUTION CHROMATOGRAPHY

In order to determine the chemical composition distribution (CCD) of s tyrene-butadiene copolymers, gradient polymer elution chromatography h as been performed. The separation is mainly based on differences in so lubility among the copolymer molecules with different chemical composi tion. The solubility of a copolymer is dependent on the following para meters: temperature, type of solvent/non-solvent mixture, molecular ma ss of the polymer and the chemical composition of the polymer. The res olution of the gradient polymer elution chromatographic separation and the molecular mass dependency are influenced by the solvent/non-solve nt combination. In order to obtain a reliable separation according to chemical composition, the differences in solubility must be sufficient ly high and the molecular mass dependence must be negligible. In order to separate styrene-butadiene copolymers, synthesized by emulsion pol ymerization, a tetrahydrofuran-acetonitrile gradient was used. After c alibration of the chromatographic system with styrene-butadiene copoly mer standards, the CCD of styrene-butadiene copolymers could be calcul ated.