The Nature of the Cross-linking Reaction in Polymers of Unsaturated Isocyanates∗

Copolymers of vinyl isocyanate, β-allyloxylethyl isocyanate, and 9-decenyl isocyanate having low mole fractions of isocyanate monomer were soluble, linear structures. However, at high mole fractions of the isocyanate monomer in the copolymer, the copolymers were insoluble and cross-linked. Evidence has been obtained which supports the postulation that the cross-links are formed at high isocyanate ratios by a mechanism similar to that by which isocyanates are converted to dimers, the uretidenedione structure, or to trimers, the isocyanurate structure.