Anionic homogeneous polymerization of acrylonitrile and methacrylonitrile by quaternary ammonium hydroxides

Aqueous solutions of quaternary ammonium hydroxides were used, for the first time, as initiators for the anionic homogenous polymerization of acrylonitrile and methacrylonitrile in dimethylformamide. The molecular weight of polyacrylonitrile was independent of catalyst and monomer concentrations, while that of polymethacrylonitrile increased linearly with monomer concentration. Infrared spectra showed the presence of primary alcohol groups in both polyacrylonitrile and polymethacrylonitrile. Polyacrylonitrile contained terminal double bonds which were absent in the methacrylonitrile polymers. On the basis of these and additional evidence, initiation by hydroxyl anion and termination by chain transfer to monomer is suggested for acrylonitrile polymerization; while termination of methacrylonitrile polymerization is by water. Molecular weight decreased with increase in size and electropositivity of the quaternary ammonium positive counterion in the following order: (CH3)4NOH > (C2H5)4NOH > (CH3)3C6H5CH2NOH.