Formation of porous flat membrane by phase separation with supercritical CO2

Microporous polystyrene membranes were prepared by the phase separation pro cess using the supercritical CO2 as a nonsolvent for the polymer solution. The thin polymer solution in a laboratory dish was located inside a cell an d the supercritical CO2 was introduced to induce the phase separation. The dry flat microporous membranes were obtained without collapse of the struct ure after the CO2 pressure was diminished. Effects of the experimental cond itions such as the CO2 pressure, the polymer concentration and the temperat ure on the average pore size and membrane porosity were investigated. (C) 2 001 Elsevier Science B.V. All rights reserved.