Effects of preparation conditions on the microstructure of porous microcapsule membranes with straight open pores

Abstract

Experimental investigations on the effects of preparation conditions on the microstructure of porous microcapsule membranes with straight open pores were carried out systematically. The polyethersulfone (PES) hollow microcapsules with straight open pores across the whole membrane thickness were prepared by a gel–sol phase inversion method together with an accompanying process for peeling off the surface dense layer. The results showed that, with increasing the PES polymer concentration, the membrane thickness of the microcapsules increased simply and the average pore size of the microcapsule membranes decreased to some extent. With increasing the concentration of inorganic additive lithium chloride, the straight pores across the microcapsule membrane became more compact and symmetrical, and the pore diameter decreased significantly; meanwhile, the membrane thickness increased to some extent. With increasing the dosages of organic additives polyvinyl pyrrolidone and polyethylene glycol, the average pore diameter of the straight pores across the microcapsule membranes decreased simply, the membrane thickness also decreased significantly. With increasing the temperature of coagulation bath in the preparation of microcapsule membranes, the average pore size of the microcapsule membranes became smaller simply, the membrane thickness also decreased gradually. With increasing the dissolution time, the average pore size of the microcapsule membranes increased slightly, and the membrane thickness of the hollow microcapsules also decreased to some extent. The results provided some guidance for the structurally controllable preparation of the hollow microcapsules with straight open pores across the membranes.