Hierarchical membrane integration of shear stress-resistant nanoparticles and biomimetic micropatterns for ultrahigh and durable biofouling resistance

Abstract

• Anti-biofouling pattern and biocidal nanoparticles were hierarchically integrated onto membranes. • Langmuir-Schaefer technique and nonsolvent-induced phase separation were rationally combined. • Silver nanoparticle integration is highly resistant to hydrodynamic shear stress (30 cm/s). • The resultant membrane enhanced biofouling resistance by 100% compared to the pristine counterpart. Herein, we report a rational strategy for fabricating dual-functional microfiltration (MF) membranes hierarchically integrated with micropatterns and Ag nanoparticles (NPs) for ultrahigh and durable fouling resistance. To harness hydrodynamic force and chemical oxidation for an enhanced anti-biofouling ability, a monolayer of Ag NPs was transferred onto negative patterns of polyurethane acrylate molds via the Langmuir-Schaefer technique. Then, they were integrated onto the biomimetic micropattern of porous polyacrylonitrile (PAN) membranes through nonsolvent-induced phase separation. Without the use of chemical linkers, our method achieved a stable and partial embedment of Ag NPs onto the porous PAN network and exhibited a negligible loss of Ag NPs even after exposure to high shear stress. Compared with the same micropatterned MF membranes without Ag NPs and the bare MF membranes, the resultant MF membrane significantly suppressed the decrease in water flux for the microbial solution by over 40% and 100%, respectively, owing to the dual anti-bacterial activities of the biocidal property of Ag NPs and the hydrodynamic repulsion of the micropatterns. Our hierarchical fabrication method can be applied to various biocidal NPs for ultrahigh biofouling-resistant porous membranes.