Photochemical Syntheses of Graft Copolymers

Photolabile groups on polymers can serve as sites for photoinitiated graft copolymerizations. For instance, when polymers and copolymers of vinyl ketone decompose in ultraviolet Imht in the presence of acrylonitrile, methyl methacrylate, or vinyl acetate, graft copolymers form  

The free radicals that are unattached to the backbone polymers, like the methyl radical shown above, also initiate polymerizations and considerable amounts of homopolymers form as well. 

It is believed that the above dye monoradicals disproportionate to hydroquinones and quinones. Transfer reactions to solvent lead to formations of homopolymers. This gives high yields of graft copolymers of methyl methacrylate with cellulose. The same is true of acrylonitrile. On the other hand, only small quantities of graft copolymers form with styrene or vinyl acetate monomers.  

It is also possible to form graft copolymers on the surface of fibers by coating them with photoinitiators, like benzophenone, together with a monomer and then irradiating them with ultraviolet light. Similar to the action of the anthraquinone dyes shown above, benzophenone in 

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