Addition Polymers of Monofunctional Isocyanates

High molecular weight polyisocyanates have aroused considerable interest since their original preparation over a decade ago. A number of papers have dealt with their preparation, their chemical structure, and their crystallinity in the solid form, but the greatest interest has centered on the unusual properties of the polymers in solution. These properties appear to be due to the extraordinarily high chain extensions which dominate solution behavior. The purpose of this article is to bring together and review critically the work published on the various aspects of these polymers. This deals mainly with methods of polymerization, chemical and crystalline structure, and conformational behavior in solution. Practically nothing has been published on the bulk properties of the polymers. Alkyl and aryl monoisocyanates have long been known to give cyclic dimers and trimers in the presence of basic reagents [l]: In 1959 Shashoua et al. [2, 3] prepared a series of high polymers from a variety of alkyl, aryl, and substituted arylisocyanates. Their products represented the first examples of addition polymerization by opening of the bond: The products were classified as N-substituted 1-nylons, by analogy with 6-nylon made from caprolactam.