Antithrombogenicity of polyethylene radiation-graft copolymerized with hydrophilic monomers

Hydrophilic monomers were graft copolymerized onto low density polyethylene (PE) by radiation peroxidation, and the relations between the antithrombogenicity and the properties or the structure of the grafted PE were studied. For the anionic grafted PE, the in vitro evaluation by a kinetic method using ACD blood was unsuitable because of its high adsorbability of calcium ion, and no good result was obtained from the in vivo evaluation by insertion of tubes into canine peripheral veins. On the other hand, for the PE grafted with nonionic hydrophilic monomers, the in vivo antithrombogenicity was increased in the following order of the monomer species: 2-hydroxyethyl methacrylate < N-vinylpyrrolidone (NVP) < 2-hydroxyethyl acrylate << acrylamide (AAm). This agreed with the order of the water wettability of the grafted PE except for NVP producing a net-like cross structure in its grafted PE. The antithrombogenicity of the AAm-grafted PE was found to exceed that of a medical silicone. (author)