Cyclic polymerization of N‐dimethacrylamides

Monomer dimethacrylamides are polymerized on heating in bulk and in solution, yielding soluble and fusible polymers which contain practically no unsaturation. Similar polymers are obtained by partial thermal deamination of polymethacrylamides at 300°C. in vacuum. Infrared spectroscopy has shown that the polymers obtained by the polymerization of the monomer N‐substituted dimethacrylamides consist of fivermembered cycles (the region of carbonyl absorption 1700‐1790 cm.−1) linked by a bridge of two methylene groups. The polymers obtained by deamination of polymethacrylamides contain six‐membered cycles (carbonyl absorption in the range from 1680 to 1730 cm.−1) linked by one methylene group. This is confirmed by a comparison of the infrared spectra of the polymers and of model compounds: imides of succinic and glutaric acids. Dimethacrylamide is an exception, its polymerization yields a polymer consisting of 5‐membered cycles as well as 6‐membered ones. X‐ray analysis shows the polymer obtained by thermal deamination of polymethacrylamide to be oriented and highly crystalline. Some properties of the polymers obtained are described.