Photograft Copolymerization of Methyl Methacrylate and Natural Rubber Using Quinoline-Bromine C.T. Complex as Photoinitiator in Benzene Solution

Photografting of poly(methyl methacrylate), PMMA chains on natural rubber (NR) chain backbones was studied in benzene solution using quinoline-bromine (Q-Br₂) charge transfer complex as photoinitiator and MMA as monomer at 35°C in visible light. Analysis of overall products for determination of grafting efficiencies was done following a method of selective extraction of only the free rubber fraction by benzene-petroleum ether mixtures followed by separation of the NR-PMMA graft copolymer from free PMMA in the residue (taken in benzene solution) by fractional precipitation with methanol. High grafting efficiencies in the range of 75–95% were easily and generally obtained. Effects of variation of concentrations of initiator, rubber, and monomer on grafting efficiencies were examined and reported. Prior photodegradation of the rubber resulted in substantial lowering in grafting efficiencies. Overall mechanism of graft copolymerization has been discussed.