Photografting on ethylene/propylene/5-ethylidene-2-norbornene rubber initiated by photogenerated hydroperoxides

Terpolymer ethylene/propylene/5-ethylidene-2-norbornene (EPDM) reacts with singlet oxygen leading to the production of polymeric pendant isolated and associated secondary hydroperoxides. Anthracene was used as a sensitizer for production of singlet oxygen under 365 nm irradiation. Irradiation (lambda 300 nm) of hydroperoxidized EPDM rubber (EPDM-OOH) in the presence of monomers grafted these monomers onto the rubber. Volatile monomers (methyl methacrylate, styrene, 2,2,6,6-tetramethyl-4-piperidyl acrylate) can be easily grafted on EPDM-OOH film by irradiation in their vapor. Nonvolatile as well as volatile monomers and some stable nitroxyl radicals were grafted onto EPDM-OOH films in methanol solution of monomers or nitroxyl radicals. Concentration of grafted monomers depends on the starting hydroperoxide concentration. Hydroperoxidation as well as grafting occurs in the films; it is not simply a surface process only.