Two-dimensional fractionation of complex polymers by comprehensive online-coupled thermal field-flow fractionation and size exclusion chromatography.

Thermal field-flow fractionation (ThFFF) was successfully coupled online to size exclusion chromatography (SEC) in a comprehensive two-dimensional configuration. In the first dimension, fractionation according to chemical composition based on the interplay of thermal and translational diffusion took place in the ThFFF channel. Fractions from the first dimension were comprehensively transferred to the second dimension, SEC, and separated according to hydrodynamic volume which is a function of molar mass. To illustrate the capabilities of this novel two-dimensional fractionation approach, polystyrene-poly (methyl methacrylate) block copolymers were comprehensively fractionated and characterized. Blends of homopolymers, homo- and copolymers, and copolymers with different compositions were fractionated and the effects of experimental conditions, the components' molar masses and compositions were investigated. The results illustrated the molar mass independence of the thermal diffusion coefficient in ThFFF. Translational diffusion coefficients were quantitatively determined via dynamic light scattering. The study aimed at proving the versatility of the comprehensive online coupling of ThFFF and SEC for the analysis of complex polymers having the ability to provide detailed molecular information (chemical composition and molar mass distribution) as well thermal and translational diffusion information in a single analysis. Finally, the merits of using information-rich detectors are highlighted.