ICAR ATRP of acrylonitrile utilizing a moderate temperature radical initiator

Initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) of acrylonitrile was first conducted at various ambient temperatures (30–45 °C). The key to success is ascribed to the usage of an appropriate low temperature radical initiator (2,2′-azobis(2,4-dimethylvaleronitrile)) and a high reactivity catalytic system (CuBr₂/Me₆TREN). The molar ratio of Cu catalyst to AN as low as 1:20000 was used to prepare well-defined polyacrylonitrile with controlled molecular weight and a narrow polydispersity index range of 1.08–1.30, while the monomer conversion was up to ca. 98%. The apparent activation energy of the polymerization was calculated to be 128.45 kJ/mol, suggesting that the polymerization strongly depended on reaction temperature. The very high chain-end functionality of the resultant polymer was confirmed by ¹H-NMR and GPC analyses as well as chain extension reaction.