Stereospecific polymerization of methacrylonitrile. I. Characterization of crystalline polymethacrylonitrile

Methacrylonitrile (MAN) was polymerized with diethylmagnesium. Acetone-insoluble portions of the polymers are found to be crystalline. Highly crystalline portions can be isolated by further extraction of the acetone-insoluble parts with dimethylformamide (DMF). A film of DMF-insoluble fraction can be oriented uniaxially by hot-press rolling. The crystalline PMAN is insoluble in the usual solvents for amorphous PMAN because of their crystallinity and is easily soluble in CF₃COOH or Cl₂CHCOOH. The viscosity–molecular weight relationship was determined in Cl₂CHCOOH at 30°C. as η] = 3.24 × 10^?3M^0.520. We found several crystalline bands in the infrared spectra, for example, at 1192 and 885 cm.^?1. Formation of the carbonyl group in the polymer is discussed, and it is concluded that it may be formed by the hydrolysis of conjugated cyclic imine or hydrolysis of the nitrile group in the polymer to acid amide.