Acrylonitrile and methacrylonitrile polymers

Polymers from acrylonitrile are used in synthetic fibers, in elastomers, and in plastic materials. The monomer can be formed by dehydration of ethylene cyanohydrin  

Other commercial processes exist, like condensation of acetylene with hydrogen cyanide, or ammoxidation of propylene  

Acrylonitrile polymerizes readily by a free-radical mechanism. Oxygen acts as a strong inhibitor. When the polymerization is carried out in bulk, the reaction is autocatalytic. In 

Acrylonitrile polymerizes also by anionic mechanism. There are many reports in the literature of polymerizations initiated bv various bases. These are alkali metal alkoxides, butvl-lithium, metal ketyls, solutions of alkali metals in ethers, sodiummalonic esters, and others. The propagation reaction is quite sensitive to termination by proton donors. This requires the use of aprotic solvents. The products, however, are often insoluble in such solvents. In addition, there is a tendency for the polymer to be yellow. This is due to some propagation taking place by 1,4 and 3,4 insertion in addition to the 1,2 placement 1 

Another disadvantage of anionic polymerization of acrylonitrile is formation of cyanoethylate as a side reaction. This, however, can be overcome by running the reaction at low temperatures. An example is polymerizations initiated by KCN at-50 °C in dimethylfonnamide, or by butyllithium in toluene at -78 Both polymerizations yield white, high molecular weight products that are free from cyanoethylation. 

Acrylonitrile polymerizes readily by free-radical mechanism. Oxygen acts as a strong inhibitor. When the polymerization is carried out in bulk, the reaction is autocatalytic [242, 243]. In solvents, like dimethylformamide, however, the rate is proportional to the square root of the monomer concentration [242]. The homopolymer is insoluble in the monomer and in many solvents. 

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