Excimer Formation of a Naphthalene Diisocyanate Based Polyurethane in Solution

摘要

Naphthyl carbamates are shown to form excimers which are stabilized by hydrogen bonding inherent in the participating species. Substitution of a methyl group on the central nitrogen atom of the carbamate moiety severely limits excimer formation. A polyurethane based on 1,5-naphthalene diisocyanate forms intramolecular excimers in dilute solutions of both good and poor solvents; however, excimer formation is significantly enhanced in poor solvents where intramolecular contact between naphthyl carbamate groups is favored. The photophysics of excimer formation in the polyurethane is interpreted on the basis of an isolated monomer scheme. By measuring the excimer to monomer intensity ratio in pure and mixed solvent systems, the solubility parameter of the polymer is estimated to be between 21 and 22 cu. m. to the 1/2 x .001.