A novel synthesis method of partially crosslinking a polymer solution prior to casting, has been successfully developed for the preparation of solvent-tolerant nanofiltration (STNF) membranes. STNF merges solvent resistant nanofiltration (SRNF) with aqueous nanofiltration.
The feed solution consists of a mixture of solvent(s) and water, requiring a membrane with both high water permeability and solvent stability. In this work, epoxy resins are proposed to meet these requirements. The well-known epoxy curing bulk chemistry via ring-opening reactions has been applied followed by a phase inversion process, to form membranes with intermediate polarity, excellent stability and permeability, making them particularly suitable for the treatment of solvent/water mixtures.
Several epoxy monomers were screened, based on size and number of epoxide functional groups. Different
amines with varying length and reactivity were chosen as curing agent. Both reagents were dissolved in dimethyl
sulfoxide (DMSO) and left to react. The increasing solution viscosity was monitored as a function of time and
related to the reaction rate of the epoxy-amine curing system. Integrally skinned asymmetric membranes were
prepared via non-solvent induced phase inversion.