Surface-initiated atom transfer radical polymerization from porous poly(tetrafluoroethylene) membranes using the CF groups as initiators

Abstract

This work reports the surface-initiated atom transfer radical polymerization (ATRP) from hydrogen plasma-treated porous poly(tetrafluoroethylene) (PTFE) membranes using the CF groups as initiators. Hydrogen plasma treatment on PTFE membrane surfaces changes their chemical environment through defluorination and hydrogenation reactions. With the hydrogen plasma treatment, the CF groups of the modified PTFE membrane surface become effective initiators of ATRP. Surface-initiated ATRP of poly(ethylene glycol) methacrylate (PEGMA) is carried out to graft PPEGMA chains to PTFE membrane surfaces. The chain lengths of poly(PEGMA) (PPEGMA) grafted on PTFE surfaces increase with increasing the reaction time of ATRP. Furthermore, the chain ends of PPEGMA grown on PTFE membrane surfaces then serve as macroinitiators for the ATRP of N-isopropylacrylamide (NIPAAm) to build up the PPEGMA-b-PNIPAAm block copolymer chains on the PTFE membrane surfaces. The chemical structures of the modified PTFE membranes are characterized using X-ray photoelectron spectroscopy. The modification increases the surface hydrophilicity of the PTFE membranes with reductions in their water-contact angles from 120° to 60°. The modified PTFE membranes also show temperature-responsive properties and protein repulsion features owing to the presence of PNIPAAM and PPEGMA chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2076–2083, 2010