Thermodynamic and kinetic aspects of phase inversion process were investigated to elucidate the mechanism of asymmetric membrane formation. A solubility parameter map of polysulfone was obtained. A solvent (NMP), a solvent additive (FA : formic acid) and a non-solvent(ethanol) were chosen on the basis of the solubility parameter map. A series of cloud points measurement resulted in a phase diagram illustrating that the polymer solution is thermodynamically unstable with increasing amount of FA in the solvent mixture. An asymmetric membrane prepared was characterized in terms of the skin structure and the cross-sectional morphology as well as the oxygen permeability. The diffusion coefficients of non-solvent into polymer solutions from the precipitation kinetics were also obtained. The sponge-like membrane was prepared with the system of the rapid exchange rate of non-solvent and solvent. This observation is contradictory to common observations. The macrovoids formation was also investigated by an optical microscope and seemed to be attributable to the non-solvent intrusion through the surface microcracks at the surface, which, in turn, related to the viscosity and surface tension of polymer solution.

상반전 과정을 통해 비대칭막의 생성기구를 조사하고, 열역학적 및 동력학적 영향을 살펴보았다. 폴리술폰의 용해도 계수지도를 얻고 이로부터 용매(NMP), 비용매(ethanol) 그리고 용매첨가제(FA:포름산)를 선택했으며 구름점 측정으로부터 상분리도를 작성했다. 용매속의 FA 함량이 증가함에 따라 용액의 열역학적 안정도가 감소했다. 폴리술폰 비대칭 막을 만들어 표면 및 단면구조를 SEM으로 관찰했으며, 산소투과도를 측정했다. 상반전과정에서의 비용매의 투과속도를 측정하였으며, 투과속도가 클 때 스폰지형 막을 만들 수 있었는데 이는 이때까지의 결과와 다른 새로운 발견이었다. 막에서의 대공형성 기구도 상반전 과정을 현미경으로 관찰하였으며 용액의 점도 및 표면장력과의 연관성을 검토했다.