Radiation grafting of hydrophilic monomers onto poly[bis(trifluoroethoxy)phosphazene]

The hydrophilic monomers dimethylacrylamide (DMAA) and acrylamide (AAm) were radiation grafted onto poly[bis-(trifluoroethoxy)phosphazene] (PTFP) for biocompatibility enhancement through direct irradiation of the polymer films immersed in monomer-solvent mixtures, and the progress of grafting was followed up to a large monomer depletion. The water absorption of the samples was found to increase as the amount of the grafted chains increased. The grafted chains, mainly confined in the film surface at high dose rates, progressively extend to the interior of the sample as the dose rate decreases. In the grafted samples the ultimate mechanical properties epsilon r and sigma r were essentially preserved. The in vivo tests indicated an enhancement of surface biocompatibility in the PTFP-g-AAm samples and not in the PTFP-g-DMAA samples.