Heparin-grafted poly(tetrafluoroethylene-co-hexafluoropropylene) film with highly effective blood compatibility via an esterification reaction

The aim of this work was to modify poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film surface in order to improve its hydrophilicity and blood compatibility. Acrylic acid (AAc) was introduced onto Ar plasma-pretreated FEP surface by UV-induced grafted copolymerization. Subsequently, heparin (Hp) was also immobilized covalently with the carboxylic group of PAAc grafted onto the FEP surface via an esterification reaction. The chemical composition and the morphological change of the modified films were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), atomic force microscopy (AFM) and water contact angel measurements. The root–mean–square average surface roughness (Ra) changed from 5.82nm (FEP) to 13.60nm (FEP-PAAc) and 11.74nm (FEP-PAAc-Hp). Water contact angles changed from 115.0o (FEP) to 32.4o (FEP-PAAc) and 44.8o (FEP-PAAc-Hp). The blood compatibility of the modified films was evaluated by platelet adhesion experiments. All results suggested that the FEP-PAAc-Hp surface presented excellent antithrombotic properties and good hydrophilicity. Therefore, this method will provide a potential and effective solution for the surface modification of medical polymer materials.