Quaternization cross-linking of hyperbranched polyethylene-graft-poly(diethylaminoethyl methacrylate) as antimicrobial separation layer of molecular sieving membrane

Abstract

Positively charged composite membranes with polyethylene-based antimicrobial separation layers are conveniently developed herein for precise molecular sieving. Quaternization cross-linking between hyperbranched polyethylene-graft-poly(diethylaminoethyl methacrylate) and 1,2-dibromoethane constructs porous networks with abundant quaternary ammonium groups. Modified membranes exhibit different interception capabilities for anions, cations, and neutral molecules. We explain the possible sieving mechanisms with respect to size exclusion, the Donnan effect, and the intrapore energy barrier. A strongly positively charged separation layer introduces the electrostatic interaction which has different effects on cationic, anionic, and neutral molecules during filtration. Membranes prepared by the simple quaternization cross-linking strategy can efficiently separate molecular mixtures with different dimensions or charges. Moreover, the plentiful quaternary ammonium groups endow the membranes with favorable antimicrobial activity against Gram-positive E. coli and Gram-negative S. aureus.