Anionic polymerization of acrylonitrile by various catalysts

Abstract

AbstractThe polymerization of acrylonitrile was studied using cyclopentadienyllithium, cyclopentadienyl sodium, fluorenylithium, and phenyllithium, and was compared to polymerization with butyllithium. With phenyllithium and fluorenyllithium in tetrahydrofuran, termination was found to be by chain transfer to monomer. The homogeneous polymerization in dimethylformamide carried out at both high and low catalyst concentrations showed that at high catalyst concentrations the molecular weights of polymer increased sharply with monomer concentration using cyclopentadienyllithium and cyclopentadienyl sodium, unlike the case of polymer obtained with butyllithium and fluorenyllithium. The increase in molecular weight is due to what has been previously found that the cyclopentadienyl anion acts as a polyfunctional catalyst leading to initiation of polymerization at various places on the ring. The basic strength of the catalyst investigated, as determined from the ability to polymerize monomers of decreasing acidity, was as follows: butyl ⋍ phenyl > fluorenyl > cyclopentadienyl.