Thermal field-flow fractionation of colloidal materials: Methylmethacrylate-styrene linear di-block copolymers

Summary Model methylmethacrylate-styrene, linear di-block, copolymers were used to investigate the respective influnnces of temperature, of molar mass and of chemical composition on their Soret coefficient, s_T, by means of thermal field-flow fractionation (thermal FFF) in toluene and in THF. A recently developed thermal FFF retention model, which takes into account the variation of the basic FFF parameter λ with temperature, is applied to investigate the dependence of the Soret coefficient on temperature. It is found that the coefficient decreases approximately linearly with increasing temperature. At constant chemical composition and temperature, s_T exhibits a power law dependence on molar mass with an exponent é ? 0.55. At constant molar mass and temperature, s_T decreases monotonously with increasing weight percent styrene in the copolymer composition. At 300 K, s_T values are slightly larger in THF than in toluene. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996.