THERMAL FIELD-FLOW FRACTIONATION OF COLLOIDAL MATERIALS - METHYLMETHACRYLATE-STYRENE LINEAR DI-BLOCK COPOLYMERS

Model methylmethacrylate-styrene, linear di-block, copolymers were use d to investigate the respective influences of temperature, of molar ma ss and of chemical composition on their Soret coefficient, s(T), by me ans of thermal field-flow fractionation (thermal FFF) in toluene and i n THE A recently developed thermal FFF retention model, which takes in to account the variation of the basic FFF parameter lambda with temper ature, is applied to investigate the dependence of the Soret coefficie nt on temperature. It is found that the coefficient decreases approxim ately linearly with increasing temperature. At constant chemical compo sition and temperature, s(T) exhibits a power law dependence on molar mass with an exponent E (a) over tilde 0.55. At constant molar mass an d temperature, ST decreases monotonously with increasing weight percen t styrene in the copolymer composition. At 300 K, s(T) values are slig htly larger in THF than in toluene.