Co-solvent-mediated synthesis of thin polyamide membranes

► A promising strategy for the synthesis of polyamide membranes. ► Acetone was added as a co-solvent in hexane phase in interfacial polymerization. ► Added acetone increased effective pore size and water flux. This study introduces a promising strategy, called co-solvent assisted interfacial polymerization (CAIP), for the synthesis of thin polyamide membranes by interfacial polymerization of 1,3-phenylenediamine (MPD) with 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone ultrafiltration supports. A synergistic co-solvent added in the hexane phase was used to control the polymerization reaction zone and modify the membrane network structure. The resultant membrane exhibited selective molecular sieving of small molecules from larger ones. The addition of larger amounts of acetone as a co-solvent to the hexane solution increased both pore size and water flux, which was determined by analysis of the membrane permeation properties. In the permselectivity test of a 500 ppm glucose aqueous solution, the best-performing membrane was prepared by 2 wt% acetone addition. It showed a rejection of more than 99.4% and a high water transport at a rate of more than 1 × 10 −11 m 3/(m 2 Pa s), which was more than 4-fold higher than the membrane prepared without acetone. The effects of reaction conditions, including co-solvent content and interfacial polymerization time, were studied.