Thermal Field-Flow Fractionation

Thermal FFF is a subtechnique of FFF in which a temperature gradient dT/dx is employed as the external field. The temperature gradient is generated by heating one plate of the channel while cooling the other plate. Molecules migrate towards the cold plate which thus becomes the accumulation wall.

Thermal FFF is the preferred subtechnique for characterizing synthetic polymers which can be dissolved in an organic solvent. Applications of thermal FFF for a wide range of organic soluble synthetic polymers and copolymers include the determination of the average molecular weight and molecular weight distributions, polydispersity especially for ultra-narrow polymer samples, and Brownian diffusion coeffient. In addition, thermal FFF has been a powerful tool for studies of thermal diffusion since it provides one of the few methods for determining the thermal diffusion coefficient of polymer molecules. Expansion of thermal FFF to a limited number of water-soluble polymers has also been conducted successfully.