Controlled grafting from poly(vinylidene fluoride) films by surface-initiated reversible addition-fragmentation chain transfer polymerization

A reversible addition-fragmentation chain transfer (RAFT) polymerization technique was applied to graft polymerize brushes of poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) monomethacrylate) (PPEGMA) from poly(vinylidene fluoride) (PVDF) surfaces. PVDF surfaces were exposed to aqueous LiOH, followed by successive reductions with NaBH4 and DIBAL-H to obtain hydroxyl functionality. Azo-functionalities, as surface initiators for grafting, were immobilized on the PVDF surfaces by esterification of 4,4'-azobis(4-cyanopentanoic acid) and the surface hydroxyl groups. The chemical composition and surface topography of the graft-functionalized PVDF surfaces were characterized by X-ray photoelectron spectroscopy, attenuated total reflectance-FTIR spectroscopy, and atomic force microscopy. Mneties studies revealed a linear increase in the graft concentration of PMMA and PPEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a "controlled" or "living" process. The living chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. (c) 2006 Wiley Periodicals, Inc.