Ionizing radiation surface modification

Surface modification of fluoropolymers either by ionizing radiation (gamma radiation or electron beam radiation) [20,21] or by chemical reactions [22], introduces reactive sites for additional chemical reactions or improves wear [20]. 

This paper summarizes chemical grafting techniques explored in this laboratory that have potential biomedical application. These reactions, initiated by ceric ions, persulfate-bisulfite redox systems, or the presence of comonomers forming donor-acceptor complexes, were carried out in an aqueous environment under conditions which, with suitable modifications, might be tolerated in vivo. Grafting onto tissue surfaces by means of ionizing radiation will not be discussed since techniques for avoiding undesirable side reactions have not yet been developed. 

Ionizing radiations are employed to neutralize corrosion-active macroradicals arising from tribochemical reactions with pol3miers. 7-radiation is known to result in the volume and surface modification of pol3mier materials as well as variation in the friction coefficient and wear rate of plastic parts [38]. 

Graft copolymerization is the most effective method utilized in the chemical modification of natural fibers. According to Gassan et al. [99], the reaction is initiated by free radicals on the fiber surface. Ionization polymerization of fibers is carried out in an aqueous solution, followed by exposure to a high-energy radiation. Fiber molecule cracks and radicals are subsequently formed. Next, the radical sites of the fiber are treated with a suitable solution compatible with a polymer such as vinyl monomer, acrylonitrile, methyl methacrylate, or polystyrene. Finally, this leads to the formation of a graft copolymer, which possesses fiber and graft polymer characteristics. 

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