Preparation of Asymmetric Membranes via Thermally Phase Separation Based on Polymer Concentration Gradient and Simulation of Asymmetric Structure Formation

摘要

Asymmetric membranes ahving smaller pores at one side and larger pores at the other side were prepared by thermally induced pahse separation of polypropylene-diphenyl ether solution with polymer concentration gradient.Thge diluent was evaported from one side of the polymer solution,thereby creating a concentration gradient prior to the phase separation.The thickness of the skin layer formed near the upper side of the membrane was influenced by the evaporation time.Analysis of the evaporation process indicated that clear polymer concentration gradient formed by the evaporation of diluent.The simulation of phase separation process by the spinodal decomposition was carried out based on Cahn-Hilliard's model.The simulation results of the pores size and the thickness of skin layer were approximately in agreement with the experimental results.