Hydrophilic and photo-crosslinkable diblock copolymers employed for robust antifouling membrane coatings

Abstract

Bifunctional copolymers bearing hydrophilic units and photo-crosslinkable units were prepared and employed to coat PVDF membranes and thus improve their antifouling properties and coating stability. A series of methoxy poly(ethylene glycol)-block-poly(2-hydroxyethyl methacrylate) (mPEG-b-PHEMA) diblock copolymers were prepared via the atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) using different mPEG macroinitiators, and then reacted with cinnamoyl chloride to obtain methoxy poly(ethylene glycol)-block-poly(2-cinnamoyloxyethyl methacrylate) (mPEG-b-PCEMA). Coating PVDF microfilter membranes with mPEG-b-PCEMA and subsequently photo-crosslinking the PCEMA block yielded crosslinked copolymer coatings. The successful preparation of these coatings was confirmed by SEM, TGA, ATR-FTIR and XPS characterization. The hydrophilicity of the membrane increased along with the amount of diblock copolymer coating on the coated PVDF membrane. Based on the results of BSA adsorption and filtration experiments, the antifouling properties of the coated PVDF membrane remarkably improved. Furthermore, the mPEG block chain length and its content in the diblock copolymer had a significant effect on the surface properties of the coated PVDF membrane. More importantly, the copolymer coatings were very stable thanks to the crosslinking of the PCEMA chains of the diblock copolymer.