Preparation of positively charged PVDF membranes with improved antibacterial activity by blending modification: Effect of change in membrane surface material properties

In this work, we present a simple one step blending modification method to fabricate antibacterial PVDF membrane. Effect of membrane surface material properties on the antibacterial activity was investigated. Firstly, a cationic copolymer containing quaternary ammonium cations was synthesized by free radical polymerization of methyl methacrylate (MMA) and dimethylamino-2-ethyl methacrylate (DMAEMA), and following quaternization by iodomethane as an alkylating agent. Via a one-step non-solvent induced phase separation (NIPS) process, blend PVDF membranes were prepared with the copolymers as additive. Only a small amount of copolymer addition (0.9 wt.%) profoundly improved antibacterial activity of the obtained membranes surafce against Escherichia coli (E. coli), as a typical model micro-organism foulant, due to enhanced hydrophilicity and incorporation of quaternary ammonium groups on the membrane surface. In particular, the quaternized copolymer using iodomethane imparted the optimized antibacterial performance with both high adhesion resistance (surface occupying, 15%) and high inactivation (cell viability, 0.15%) to E. coli cells.