Evolution of well-characterized macromolecules containing aromatic substituents whose excited-state decay kinetics can be adequately described by simple models would be invaluable in attempts to evaluate the conjunct roles adopted by energy and material diffusions within intramacromolecular energy-transfer processes. Achievement of simple temporal dependences, even under the conditions of the high local chromophore concentrations encountered within coiled polymers in fluid solution, might be sougth either through structural design of the macromolecule or by incorporation of chromophores of appropriate photophysics, such that self-quenching interactions are precluded. In this context, it has been reported (Hargreaves, J. S.; Webber, S. E. Macromolecules 1984, 17, 235) that the time-resolved fluorescence behavior of the "phenylanthracene-based" polymer system poly[(10-phenyl-9-anthryl)methyl methacrylate], PPA, may be adequately modeled by a first-order decay law. In this paper, it is shown that rigorous analysis of PPA fluorescence decays recorded under magic angle sampling conditions following pulsed excitation using the Synchrotron Radiation Source (Daresbury, UK) reveals that the excited-state decays are not single exponential in character. It is proposed that the observed complexities might have origins in the formation of an excited-state complex of low emissivity. © 1991 American Chemical Society.
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|Published - 1991