Polymer Solutions under High Pressures

Phase behavior and the phase separation dynamics of §polymers in fluid and fluid mixtures are of §importance for many processes encountered in polymer §synthesis, purification, processing, and §modifications. High pressure fluids/fluid mixtures, §i.e. near-critical or supercritical fluids, have §been considered as a replacement for many §conventional organic solvents because they are §environmentally benign and tunable for processing. §As one of the approaches to achieve this goal, §binary mixtures of an organic solvent and CO2 under §high pressures can be used to replace the organic §solvents. This book discusses the phase behaviors §and phase separation dynamics of two model polymers §in such systems. The polymer systems chosen are §polysulfone in tetrahydrofuran and CO2 mixtures and §polyethylene in n-pentane and CO2 mixtures. The §former system is selected in that polysulfone is a §very important commercial polymer for membrane §formation, for which phase separation is the key to §desired structure. The latter is chosen as a model §system for semicrystalline polymers to study the §fluid-fluid and solid-fluid phase separations and §their interplay.