LAUSR

The steady-state fluorescence (SSF) spectra and time-resolved fluorescence (TRF) decays of five poly(isobutylene-alt-maleic anhydride) copolymers (PIMA), randomly labeled with N-(1-pyrenylmethyl)succinimide groups (Py-PIMA), have been analyzed in order to describe their long-range, polymer chain dynamics (LRPCD) and to assess the stiffness of the PIMA backbone compared to that of a series of poly(alkyl methacrylate)s whose LRPCD had already been investigated. The SSF spectra, recorded under dilute concentration conditions where only intrachain events are important, show that the intensity ratio of pyrenyl excimer to pyrenyl monomer emission (i.e., (IE/IM)SSF) increases linearly with increasing pyrenyl content as a result of increased pyrenyl–pyrenyl contacts and diffusive encounters. The slope of the straight line, m(IE/IM), that reflected the efficiency of pyrenyl excimer formation for Py-PIMA, was found to be 60% smaller than for even poly(octadecyl methacrylate) (PC18MA), a polymer exhibiting slow LRPC...