Durable surface modification of poly(tetrafluoroethylene) by low pressure H_2O plasma treatment followed by acrylic acid graft polymerization

摘要

In order to obtain a durable and homogeneous surface functionalization of poly(tetrafluoroethylene) (PTFE), a two step procedure based on low pressure plasma treatment followed by a grafting reaction was used. PTFE foils and plasma deposited fluorocarbon polymer films with a chemical structure close to PTFE were investigated. The fluoropolymer surfaces were treated with microwave water vapor plasma to introduce functional groups and radicals. The generated radicals were utilized as reactive species for the gas phase graft polymerization of acrylic acid. A homogeneous and stable poly(acrylic acid) (pAAc) layer with a thickness of about 70 nm was formed. The influence of the grafting period and the acrylic acid vapor pressure on the amount of grafted pAAc was studied. The properties of the modified surfaces were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, spectroscopic ellipsometry, electrokinetic measurements and dynamic contact angle measurements. The grafted surfaces can be used for a covalent protein immobilization.