Radiation grafting of N-vinylpyrrolidone into silicone tubes. Synthesis of polymers with improved hemocompatibility and implantation tests in lambs

NVP was grafted onto silicone 2 mm I.D. tubes by the 'direct' radiation method. Homogeneous bulk grafting was carried out in toluene solution; the best results were obtained in 70% monomer solution, so it was chosen for preparing the samples for the implantations (in vivo tests). In 7 days implantation test the significant improvement of blood compatibility corresponds to grafting ratios higher than 40%. Surface limited grafting is realized in dilute aqueous solutions of NVP. The thickness of the grafted layer inside and outside the tubes is measured after coloration and observation with a microscope. The surface grafting ratio is determined by multiple reflection I.R. analysis. (author)