Improvement of Antithrombogenicity of a Fluoro Polymer by Radiation-induced Grafting of Hydrophilic Monomer

Abstract

Fluoro polymers have been used as biomaterials in medical field since they have good compatibility with both tissue and blood, and their biomaterial application are of variety. Blood compatibility of fluoro polymers, however, are not always enough for every applications. Especially, there is a large difficulty in the application for artificial vessel with small radius below than 4 mm.
In the pres ent study, grafting of a hydrophilic monomer onto a fluoro polymer has been carried out to improve blood compatibility of the fluoro polymer. The technique of grafting employed here was simultaneous irradiation method of gamma rays from a ⁶⁰Co source. The fluoro polymer and the hydrophilic monomer used in the experiment were alternative copolymer of ethylene and tetrafluoethylene(AFLON) and N, N-dimethylacry lamide(DMAA), respectively.
After grafting, it was found by in vitro tests that antithrombogenicity of AFLON was improved by grafting of DMAA. It was, however, also found that degree of the improvement is affected by grafting conditions. When ethyl acetate was used as a solvent for the graft copolymerization, the improvement was affected by dose rate. Blood compatibility of DMAA-g-AFLON obtained at a higher dose rate of 1×10⁵ rad/h was not improved, while it was improved in the sample of DMAA-g-AFLON obtained at a lower dose rate of 1×10⁴ rad/h. On the other hand, when acetone was used as a solvent for the grafting, the degree of grafting gave a significant effect on the improvement. Blood compatibility of all samples with grafting percent more than 20% was improved by grafting of DMAA.,