Kinetics of polymerization of nitroethylene. II. Study of molecular weights (by cryoscopic method)

The study of the polymerization of nitroethylene in methyl ethyl ketone and catalyzed by bases of the pyridine series—as reported in part I—was extended in the present work. The MW of a number of polymers was determined by a semimicro cryoscopic method, which is described in detail. Of all the reaction parameters, at 20°C., the MW was found to depend only on the initial monomer concentration. To account for this dependence, an additional step was included in the three‐step mechanism suggested earlier, namely, that of catalyst transfer to monomer. Spectroscopic examination of the polymers support the suggestion that termination, or transfer, is accompanied by ring closure and the formation of cyclic structures.