Effects of Additives in Radical Graft Polymerization of Vinyl Monomers onto Polybutadiene

Abstract

Effects of additives in radical graft polymerization of vinyl monomers onto 1, 2 and 1, 4polybutadiene were studied by using α, α'-azobisisobutyronitrile (AIBN) as an initiator in ben zene at 60°C. The grafting efficiency of vinyl monomers onto polybutadiene decreased in the order of acrylamide, methyl methacrylate (MMA), vinyl acetate and styrene. In the graft polymerization of MMA, the grafting efficiency and the degree of grafting increased by adding a small amount of Lewis acid (AlCl₃, ZnCl₂) but then decreased by further addition. In the graft polymerization of styrene, they increased with increasing the quantity of Lewis acid (AlCl₃, ZnCl₂). These results would be due to the complex formation between styrene and Lewis acid, which affects the graft polymerization. Complex formation between MMA and Lewis acid would accelerate both homopolymerization and grafting reaction. The order of the effect of Lewis acid on the degree of grafting and the grafting efficiency in the graft polymerization of styrene onto 1, 2-polybutadiene was as follows: ZnCl₂>AlCl₃>ZnI₂ Lewis base did not affect the degree of grafting and the grafting efficiency. In the graft polymeri zation onto 1, 4-polybutadiene, Lewis acid and Lewis base had little effects for the grafting efficiency and the degree of grafting. Zinc iodide retarded the graft polymerization.