Nanocomposite membranes from nano-particles prepared by polymerization induced self-assembly and their biocidal activity

Silver ions have been widely used because of their antimicrobial properties. This study describes the production of novel nanocomposite membranes from a block copolymer and silver nanoparticles (NPs). These composite membranes display properties from both polymeric and inorganic materials along with the biocidal features obtained due to the presence of silver ions. The spin coating technique is employed to synthesize the nanocomposite membrane consisting of positively charged inorganic NPs and negatively charged polymeric NPs. Polymeric NPs of spherical, wormicular, and vesicular morphologies were synthesized using Reversible addition-fragmentation chain transfer (RAFT) polymerization using poly(methacrylic acid)-b-(methyl methacrylate) diblock copolymer. The silver NPs coated with poly(methacrylic acid)-b-poly(quaternized 2-(dimethylamino)ethyl methacrylate), were synthesized using a nanoprecipitation method. The silver NPs act as the bridging entity between the polymeric NPs, as well as conferring the antimicrobial activity to the composite membranes. To test their antimicrobial properties, membranes were incubated with Enterococcus hirae. Comparison with the controls shows a 2 to 3 log decrease in the bacterial count for a contact time of 24 h. Furthermore, membrane filtration experiments conducted with phosphate buffer saline solutions spiked with bacteria indicated the importance of incorporating silver NPs in the nanocomposite membrane to achieve considerable rejection of bacteria as well as biocidal activity.