A stable and hydrophilic substrate for thin-film composite forward osmosis membrane revealed by in-situ cross-linked polymerization

A stable and hydrophilic substrate is of critical significance for forward osmosis (FO) membrane with excellent performance. This study presents a simple, facile and efficient approach for the fabrication of polyethersulfone/poly (acrylic acid) thin-film composite forward osmosis (TFC FO) membrane through in-situ cross-linked polymerization and interfacial polymerization. The resulting network structure improves the hydrophilic stability of membranes. Compared with the pristine membrane, the blending membrane exhibits not only more than four times decrease in structural parameter, but also higher water flux (up to 32.9 and 56.3 L m−2 h−1 under forward osmosis and pressure retarded osmosis mode). In addition, poly (acrylic acid) chains can form ionic bonds with the m-phenylenediamine during the interfacial polymerization, resulting in a better polyamide layer, high salt rejection and long-term stability. This research opens a new avenue to improve the performance of TFC FO membrane by in-situ cross-linked polymerization.