Photophysics of 1,5-Naphthalene Diisocyanate-Based Polyurethanes

Document Type

Article

Publication Date

11-30-1987

Department

Polymers and High Performance Materials

Abstract

Using both steady-state and transient fluorescence decay spectroscopy, the formation of intramolecular excimers in dilute solution of a naphthalene diisocyanate based polyurethane is identified. Investigation of an appropriate model compound leads to the conclusion that hydrogen bonding is a key factor in stabilizing excimers formed from naphthyl carbamates. While the decay kinetics of the model naphthyl carbamate are described by a typical Birks excimer scheme involving a single excited species in dynamic equilibrium with the excimer, the polymer decay kinetics can only be adequately interpreted by an "isolated monomer" scheme involving both an interactive (excimer forming) and non-interactive (isolated monomer) excited naphthyl carbamate moiety. The extent of excimer formation is dependent on the ability of the solvent to solvate the polyurethane, i.e., excimer formation is increased in poor solvents. In addition, excimer formation in solid polyurethane films is quite high where hydrogen bonding, as identified by the shift in the carbonyl stretching frequency, is prevalent.

Publication Title

ACS Symposium Series

Volume

358

First Page

201

Last Page

218

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