Alternating copolymerization and cyclocodimerization of acrylonitrile and butadiene in the presence of zinc chloride

The copolymerization of acrylonitrile (AN) and butadiene (BD) in the presence of zinc chloride was studied in further detail. The reaction yields as 1:1 copolymer of AN and BD together with varying amounts of the AN/BD cyclodimer 4‐cyanocyclohexane. The effects of varying monomer feed composition and molar proportion of ZnCl 2 /AN on the yield of the copolymer were determined. Further, it was observed, that the addition of free radical initiators and inhibitors markedly influence the course of the reaction. Initiators significantly reduce the polymerization induction period, characteristic of this copolymerization and enhance the yield of copolymer. Inhibitors conversely reduce the formation of copolymer but enhance formation of the cyclocodimer AN/BD. Addition of styrene (ST) to the system BD/AN/ZnCl 2 significantly increases the polymerization rate and results in the formation of a terpolymer AN/BD/ST containing 50 mole‐% AN. Based on these results, various aspects of the copolymerization mechanism of AN with BD catalyzed by ZnCl 2 are discussed.