In situ study on kinetic behavior during asymmetric membrane formation viaphase inversion process using raman spectroscopy

Asymmetric membrane formation has been studied by using an in situ analysis developed with a Micro Raman spectroscopy, which emphasizes kinetic aspect s of the phase inversion process. Changes in composition with time was succ essfully measured on the gelation bath-side as well as inside the precipita ted phase for the polymer/solvent/nonsolvent system of polysulfone/1-methyl -2-pyrrolidinone/ethanol. The results shows that resulting relative mass tr ansfer rates of solvent and nonsolvent during the phase inversion process s trongly influence the final membrane morphologies. In addition, ternary com positions at which phase separation initiates were explored by analyzing th e coagulation front. (C) 2000 John Wiley & Sons, Inc.