MN as a rate-accelerating additive for styrene polymerization mediated by TEMPO

Styrene polymerization mediated by TEMPO was distinctly accelerated by the addition of small amounts of malononitrile(MN). The polymerization proceeded in a living fashion as indicated by the increase in molecular weight with time and conversion and relatively low polydispersities. It was found that the polymerization rate was so quick that the conversion reached 70% within 1 h at 125 ℃ when n(MN)∶ n(TEMPO) equaled to 4∶1. Moreover the molecular weight could be controlled to 10 5 and the reaction temperature could be reduced to 110 ℃. Analysis of 1H NMR showed that MN only acted a catalyst to enhance the polymerization rate and reduce clearly the temperature by weakening the bond of C-O.