Zwitterionic pyrazole functionalized PS-b-P4VP block copolymer membranes with enhanced Anti(−bio)fouling properties

Abstract

Self-assembly of block copolymers (BCPs) offers numerous advantages in forming membranes with ordered porous architectures, showcasing their potential applications in membrane-based separation applications. However, the spontaneous accumulation of various foulants or biofoulants on the membrane surface severely hampers their practical applicability. Establishing stable functionalization of BCPs to create an anti(−bio)fouling surface without compromising the porous morphology of membranes is an ideal choice. In this context, we fabricated an isoporous membrane through the self-assembly of polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) BCP followed by covalent functionalization of pyridine moieties with zwitterionic pyrazolium moieties to obtain dual-charged (containing quaternized pyridinium and zwitterionic pyrazolium moieties) BCP-Py-Z membrane. The functionalization imparted anti(bio)fouling properties to the membranes. After post-functionalization, the quaternized pyridine and sulfobetaine pyrazolium moieties were thoroughly characterized using various techniques. Benefitting from this modification, the BCP-Py-Z membrane exhibited robust bactericidal properties against both E. coli and S. epidermidis bacteria and resulted in reduced fouling with organic compounds. Compared to the pristine BCP membrane, which is severely affected by fouling, the BCP-Py-Z membrane exhibits a much higher BSA rejection (∼95 %) and flux recovery (∼92 %). Most importantly, the BCP-Py-Z membrane consistently maintained its water filtration and flux recovery tendency throughout the continuous dynamic fouling experiment cycle. This work embodies a straightforward and stable surface functionalization method to endow BCP membrane with a strong antifouling surface, which proves advantageous for various membrane-based filtration applications.