Poly(vinylidene fluoride) Membranes with Hyperbranched Antifouling and Antibacterial Polymer Brushes

Graft copolymers of poly(vinylidene fluoride) (PVDF) with poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA) side chains (PVDF-g-PDMAEMA copolymers) were synthesized via activators generated by electron transfer for atom transfer radical polymerization (AGET-ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) directly from the secondary fluorine atoms on the PVDF backbone. Microporous membranes were fabricated from the PVDF-g-PDMAEMA amphiphilic copolymers by phase inversion in an aqueous medium. After quaternization by propargyl bromide, the resulting PVDF-g-PQDMAEMA membrane and pore surfaces bearing pendant propargyl moieties could be further functionalized via surface-initiated alkyne-azide click reaction of azido-terminated hyperbranched polyglycerols (HPG-N-3) to form the PVDF-g-P[QDMAEMA-click-HPG] membranes. The PVDF-g-P[QDMAEMA-click-HPG] membranes exhibit good resistance to protein adsorption and fouling. Alternatively, alkyne-azide click reaction of azido-terminated polyethylenimine (PEI-N-3) on the PVDF-g-PQDMAEMA membranes, followed by quaternization with 1-bromohexane, produce the PVDF-g-P[QDMAEMA-click-QPEI] membrane which is effective in reducing bacterial growth and proliferation under continuous-flow conditions.