Characterization of Polymers by Thermal Field-Flow Fractionation
Thermal field-flow fractionation (ThFFF) is a useful technique for separating complex polymer mixtures. The unique features of ThFFF make it applicable to many polymers that are difficult to characterized by conventional methods. Advances in channel design, spearheaded by work at the University of Utah's Field-Flow Fractionation Research Center, have recently culminated in the introduction of a commercially available instrument. Motivated by this progress, ThFFF is reviewed in this paper with an emphasis on implementation. Theories governing retention, zone dispersion and optimization are summarized. Procedures for obtaining accurate molecular-weight distributions on polymers are reviewed along with sample handling techniques. Also discussed is the application of ThFFF to studies of thermal diffusion in polymer solutions. The paper concludes with a discussion of current trends in the field.