Microporous membrane formation via thermally induced phase separation. I. Solid-liquid phase separation

Microporous membranes have been prepared via thermally-induced solid-liquid phase separation of polymer-diluent mixtures. The thermally-induced solid-liquid phase separation process is discussed in terms of the solution thermodynamics of the binary mixture and the crystallization kinetics. Solid-liquid phase separation proceeds via nucleation and growth of polymer crystals to produce a variety of structures. Polypropylene, high density polyethylene, polychlorotrifluoroethylene, poly(4-methyl-1-pentene) and poly(vinylidene fluoride) membranes are presented as examples.