Crosslinked PVDF-membranes for solvent resistant nanofiltration

Crosslinked poly(vinylidene difluoride) (PVDF) nanofiltration membranes were prepared and tested for solvent resistant nanofiltration (SRNF) and solvent tolerant nanofiltration (STNF, i.e. in solvent/water media) applications. The performance of the membranes was assessed by filtering ethanol (EtOH), iso-propanol (iPrOH), acetonitrile (ACN), dimethylformamide (DMF) or toluene (Tol) solutions containing Rose Bengal (RB), a 1017 Da solute. During these consecutive filtrations, the membranes displayed a solvent activation effect which was characterised by TEM, ATR-FTIR and via intermediate EtOH filtrations. This solvent activation resulted in a more permeable membrane (by a factor of 11), without loss in retention. Drying the membranes from MeOH resulted in a further increase of the RB retention in ACN and Tol to 98%. The stability of the membranes was characterised using SEM, weight loss analysis and ATR-FTIR. In STNF, a 99% RB retention was achieved from a 1:4 DMF/water mixture.