GAS-PERMEATION PROPERTIES OF ASYMMETRIC POLYCARBONATE, POLYESTERCARBONATE, AND FLUORINATED POLYIMIDE MEMBRANES PREPARED BY THE GENERALIZED DRY-WET PHASE INVERSION PROCESS

Essentially defect-free, ultrathin asymmetric polycarbonate, polyestercarbonate, and 6FDA-IPDA polyimide membranes were prepared by a dry/wet phase inversion process using forced-convective evaporation. The pure gas permeation properties of these membranes were determined for N2, O2, He, CO2, and CH4. The average apparent skin-layer thicknesses of the membrane samples varied between 330 and 580 angstrom, which is substantially thinner than for previous defect-free membranes formed by the conventional wet phase inversion process. This study indicates that the dry/wet phase inversion process appears to be universally applicable to form ultrathin, defect-free asymmetric membranes from hydrophobic, glassy polymers.