PEGylation of anti-biofouling polysulfone membranes via liquid- and vapor-induced phase separation processing

This work describes the PEGylation of a polysulfone (PSf) membrane incorporated with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, Pluronic F108) via two different approaches for PEGylated membrane formation, including liquid-induced phase separation (LIPS) and vapor-induced phase separation (VIPS). Segregated and dispersed PEGylated domains on PSf membrane surfaces were achieved by LIPS and VIPS. The chemical composition and physical microstructure of the various PEGylated PSf membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) measurements. The results show that the amount of adsorbed proteins and attached bacteria on the modified PSf membranes not only depends on the surface hydrophilicity and hydration capacity but also on the phase separation structures of PEGylated domains distributed on the PSf membrane surface. By controlling the surface uniformity of PEGylated domains, it is possible to highly regulate the PSf membrane to resist the adsorption of proteins and the attachment of bacteria. It was found that the PSf membranes prepared by the VIPS process present a higher polymer chain mobility of PEO-PPO-PEO than those prepared during the LIPS process, resulting in nano-structured phase separation during membrane formation. Consequently, the membranes prepared by VIPS have a better anti-biofouling character with respect to bacterial resistance. This work suggests that membrane formation by controlling PEO-PPO-PEO copolymer structures in nano-scale blending using the VIPS process shows great potential in the molecular design of anti-biofouling membranes for use in ultrafiltration applications. (C) 2012 Elsevier B. V. All rights reserved.