Surface characterization of binary grafting of AAc/NIPAAm onto poly(tetrafluoroethylene) (PTFE)

The present study shows results on radiation grafting of acrylic acid (AAc) and N-isopropylacrylamide (NIPAAm) mixtures onto polytetrafluoroethylene (PTFE) films. The main objective is to use the modified polymer for immobilization of the avidin-streptavidin systems or other bio-compounds. Grafting onto PTFE was carried out by the pre-irradiation oxidative method in air at different dose rates and irradiation doses. The irradiation was produced with the electron beam of a 2 MV van de Graaff accelerator, and gamma-rays, from a Gamma Beam 651 PT. The samples were placed in glass ampoules with the AAc and NIPAAm mixtures, in an aqueous solution. Graft polymerization was performed by heating of the polymer-monomer composition in an argon atmosphere at temperature of 50 °C. Surface funcionalization was studied by X-ray photoelectron spectroscopy (XPS); morphology of the surface was studied by scanning electron microscopy (SEM) and hydrophylization of the surface, by contact angle measurements (static method).