Photophysics of Polyurethanes Based on 1,5-Naphthalene Diisocyanate in Solution and Film.
UNIVERSITY OF SOUTHERN MISSISSIPPI HATTIESBURG DEPT OF POLYMER SCIENCE
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Using both steady-state and transient fluorescence decay spectroscopy, the formation of intramolecular excimers in dilute solutions 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 monomer species in dynamic equilibrium with the excimer, the polymer decay kinetics can be adequately interpreted by an isolated monomer scheme involving both an interactive excimer forming and non-interactive isolated monomer excited naphthyl carbamate monomer. 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.
- Radiation and Nuclear Chemistry
- Atomic and Molecular Physics and Spectroscopy