Stimuli-responsive microfiltration membranes and surfaces from copolymers with grafted functional side chains

Abstract

Molecular graft polymerization (bulk modification) was carried to synthesize stimuli-responsive polymeric materials. New graft copolymers, PAAc-g-PVDF, P4VP-g-PVDF and PNIPAAM-g-PVDF, were successfully synthesized through the molecular graft copolymerization of acrylic acid (AAc), 4-vinylpyridine (4VP), N-isopropylacrylamide (NIPAAM) with the ozone-preactivated poly(vinylidene fluoride) (PVDF) backbone. The microporous membranes prepared from these stimuli-responsive polymeric materials by phase inversion technique exhibit strongly pH- or temperature-sensitive properties. The present studies have shown that molecular functionalization by graft copolymerization prior to membrane fabrication is a relatively simple approach for the preparation of membranes with uniform surface (including the pore surfaces) properties. The smart polymer brushes (PAAc and PNIPAAM side chains) can be used as physicochemical gates to control the permeability through the porous PVDF membranes and can be also used as a polymeric matrix for enzyme immobilization and cell culture.