Kinetics and mechanism of copolymerization of styrene with acrylonitrile using triphenylbismuthonium 1,2,3,4-tetraphenylcyclopentadienylide as the radical initiator

The radical copolymerization of styrene with acrylonitrile in dioxan at 60 +/- 0.1 degrees C for 1 h. in the presence of triphenyl-bismuthonium 1,2,3,4-tetraphenylcyclopentadienylide follows ideal kinetics, with bimolecular termination and results in the formation of alternating copolymer as evidenced from the values of the reactivity ratios as r(1) (Sty) = 0.266 and r(2) (AN) = 0.054. The overall energy of activation is computed to be 21 kJ mol(-1). The FTIR spectrum of the copolymer shows the presence of bands at 3054 cm(-1) assigned to the phenyl group of styrene and at 2238 cm(-1) assigned to the cyanide group of AN. The H-1-NMR spectrum of the copolymer shows peaks between 7.25 and 7.71 delta assigned to the phenyl protons of styrene. The nitrogen percent for AN was evaluated by elemental analysis.