Microporous anisotropic phase inversion membranes from bisphenol-A polycarbonate: study of a ternary system

The aim of this work was to investigate anisotropic microporous membrane fo rmation by phase inversion; using immersion precipitation technique and a t ernary polymer system consisting of bisphenol-A polycarbonate, N-methyl-2-p yrrolidone as solvent and water as non-solvent to the polymer. Membrane mor phology was observed by scanning electron microscopy (SEM) and related to s ome variables involved in membrane synthesis with the help of cloud-point m easurements and precipitation kinetics, determined by means of light transm ission experiments. The results show that the studied system presents a ver y small miscibility gap, which favors instantaneous demixing and the mechan ism of nucleation and growth of the polymer lean phase, as well as macrovoi d formation, yielding membranes with big macrovoids and low-pore interconne ctivity, when directly immersed into a non-solvent bath. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.