Photophysics of Pyrenyl-Functionalized Poly(isobutylene-alt-maleic anhydride) and Poly(isobutylene-alt-maleic N-alkylimide). Influence of Solvent, Degree of Substitution, and Temperature

Abstract

A series of polymers derived from poly(isobutylene-alt-maleic anhydride) (PIMA) with ca. 1% to >90% of the anhydride units randomly substituted with 1-pyrenylmethylimido groups (Py-PIMA) has been synthesized and characterized. The remaining anhydride units in the Py-PIMA with 10% pyrenyl substitution have been converted to N-hexyl and N-decyl imides. The photophysical properties of these polymers, as obtained from steady-state fluorescence intensities, time-correlated single photon counting experiments, and time-resolved emission spectra, have provided insights into the dependence of the polymer conformations and their labilities on the degree of pyrenyl substitution, the nature of the appended alkyl chains, temperature, and solvent properties according to the Flory interaction coefficient and Hansen solubility parameters. None of the solvent characteristics, alone, can account for all aspects of the polymer behavior. The interactions of the medium with the polymer chains and the excited singlet states of...