Surface modification of poly(tetrafluoroethylene) films via grafting of poly(ethylene glycol) for reduction in protein adsorption

Poly(tetrafluoroethylene) (PTFE) films with surface grafted poly(ethylene g lycol) (PEG) chains were prepared by two methods: (1) UV-induced graft copo lymerization of methoxy poly(ethylene glycol) monomethacrylate (PEGMA) onto the plasma-pretreated PTFE films; and (2) coupling of the hydroxyl groups of PEG via ester linkages with the carbonyl chloride groups which were intr oduced onto the acrylic acid (AAc) graft-copolymerized PTFE surface through reaction with thionyl chloride (SOCl2). The UV-induced graft copolymerizat ion of PEGMA onto the plasma-pretreated PTFE film was explored with differe nt macromonomer concentrations and different UV graft copolymerization time , The coupling reaction, on the other hand, was explored with PEG of differ ent molecular weights. The surface microstructures and compositions of the PEG-modified PTFE films from both processes were characterized by contact a ngle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy ( AFM) measurements. In general, higher macromonomer concentration and longer UV graft copolymerization time led to a higher graft yield for the UV-indu ced graft copolymerization with PEGMA. Contact angle measurements revealed that the hydrophilicity of the PTFE film surface was greatly enhanced by th e grafting of the PEG chains. The PTFE surface with a high density of graft ed PEG was very effective in preventing bovine serum albumin adsorption.