Graft frequency of graft copolymers by chain transfer of growing polymer radicals to trunk polymers containing nitro groups

摘要

AbstractThe relationship between the chain transfer constant, extent of monomer conversion, and number of branches was derived for the graft copolymerization through chain transfer of growing polymer radicals to the pendent aromatic nitro groups on the trunk polymer. The equation derived enables us to predict the number of branches for a given monomer trunk polymer. The relationship obtained is compared with the experimental data previously reported for the graft copolymerization of styrene onto poly(vinylp‐nitrobenzoate). The value of α′, the ratio of nitro groups with branches to those which are attacked by polystyrene radicals, is less than unity except for the graft copolymers obtained with high initiator concentrations and at early stages of the reaction. This lowering of α′ is attributed to the steric hindrance of branches already formed on the trunk polymer which prevents the attack of polystyrene radicals on the nitro groups and side reactions, such as reaction of the nitroso groups formed as an intermediate with