Fabrication of polysulfone membrane via thermally induced phase separation process

Polysulfone (PSF) membranes were successfully prepared by thermally induced phase separation (TIPS) using dipropylene glycol dibenzoate (DPGDB) as the diluent for the first time. Interestingly, the typically liquid-liquid (L-L) phase separation with coarsening process was not observed and the gelation occurred for the system during the cooling process. Moreover, the cross-section morphologies of all the membranes showed the network structure for the PSF concentration is in the range of 17wt%–21wt%. The membrane formation mechanism concerning the phase separation-gelation was proposed. The rejection of bovine serum albumin (BSA) of the membrane increased from 83.5% to 95.9% with the increase of PSF concentration. Additionally, the maximum break strength the membrane was as high as 7.3 MPa. The present study may open a new method to fabricate PSF membrane and control membrane structure.