Thermal Separation Force
Thermal Field-Flow Fractionation is a technique which is ideally suited for the characterization of polymers, gels and nanoparticles using different organic solvents and to get additional chemical information about the polymers. Different from the other Field-Flow Fractionation sub-techniques, Thermal Field-Flow Fractionation can separate polymers not only by molar mass but also by chemical composition at the same time. Thus, Thermal Field-Flow Fractionation can separate two polymer fractions of different material (e.g. PS and PMMA) but same molecular weight into independent peaks. As the other Field-Flow Fractionation techniques, also Thermal Field-Flow Fractionation was invented und first published by Prof. Giddings.
The Separation Principle
In Thermal Field-Flow Fractionation the separation force is established by applying a temperature gradient. The top wall of a Thermal Field-Flow Fractionation channel is heated up and the bottom wall of a Thermal Field-Flow Fractionation channel is cooled. The typical temperature difference between the cold and the hot wall used in Thermal Field-Flow Fractionation is ranging between 20 and 100°K. By using temperature gradients a broad molar mass range of polymer samples can be separated in Thermal Field-Flow Fractionation analogue to the use of cross flow gradients in Flow Field-Flow Fractionation systems.
