Alternating copolymerization of vinyl pyrrolidone with methyl methacrylate using triphenylbismuthonium 1,2,3,4- tetraphenylcyclopentadienylide as a radical initiator

The radical copolymerization of methyl methacrylate with vinyl pyrrolidone in dioxan at 60 ± 0.1°C for 1 hr. in the presence of triphenylbismuthonium 1,2,3,4-tetraphenylcyclopentadienylide follows ideal kinetics and results in the formation of alternating copolymer. The activation energy is 51 kJ/mol. The FTIR spectrum of the copolymer(s) shows the bands at 1730 cm–1 and 1681 cm–1 for methoxy group and carbonyl group of methyl methacrylate and vinyl pyrrolidone, respectively. The 1H-NMR spectra of the copolymers show peaks in the range 3.70-375  due to methoxy protons of methyl methacrylate. The values of reactivity ratios calculated by Kelen-Tüdos method are r1(VP) = 0.0035 and r2(MMA) = 0.081. The ESR spectrum shows that the ylide dissociates to form a phenyl radical, which brings about the polymerization. The glass transition temperature (Tg) of the copolymer determined by DSC, is 130°C.