Rapid detection of compositional drift of polydisperse copolymers using thermal field-flow fractionation and multi-angle light scattering

The use of thermal field-flow fractionation (ThFFF) wit multi-angle light scattering MALS) for the rapid detection of compositional heterogeneity in random copolymers is demonstrated. Soret coefficients were directly calculated from the ThFFF retention times while the MALS detector provided the polymer's radius of gyration (R-g) distribution. From R-g, the diffusion coefficient (D) could be calculated and this allowed, in combination wit the Soret coefficient, th calculation of the thermal diffusion coefficient (D-T). It was shown that the D-T distribution can serve as a measure for the chemical composition distribution of random styrene acrylonitrile copolymers. Comparison of ThFFF-MALS results with literature data from ThFFF-hydrodymamic chromatography HDC) cross-fractionation experiments showed a fair agreement.