Surface-functionalizable membranes of polycaprolactone-click-hyperbranched polyglycerol copolymers from combined atom transfer radical polymerization, ring-opening polymerization and click chemistry

Hyperbranched polyglycerols containing terminal alkyne and alkyl bromide groups (CHC-HPG-Br) were first synthesized via propargyl alcohol-initiated ring-opening polymerization (ROP) of glycidol, followed by reaction of 2-bromoisobutyryl bromide (BIBB) with the hydroxyl groups to introduce the atom transfer radical polymerization (ATRP) initiators on HPG. Hydrophobic azido-terminated poly(ε-caprolactone) (PCL-N3), prepared a priori via 2-azidoethanol-initiated ROP of ε-caprolactone, was then coupled to the CHC-HPG-Br polymer through a Cu(I)-catalyzed alkyne–azide click reaction. The resultant linear-hyperbranched PCL-click-HPG copolymers were cast by phase inversion in an aqueous medium into microporous membranes of well-defined and uniform pores. Not only could the HPG contents in the PCL-click-HPG copolymers be used to control the pore size and porosity of the resulting membranes, but also the alkyl halide chain-ends of HPG allowed the subsequent functionalization of membrane and pore surfaces. The PCL-click-HPG-b-PMPC membrane was prepared via surface-initiated ATRP of zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) from the PCL-click-HPG membrane and pore surfaces. The PCL-click-HPG-b-PMPC membranes exhibit good antifouling and antibacterial adhesion properties with negligible cytotoxicity effects, making the membranes potentially useful for biomaterials and biomedical applications.