PHOTOPHYSICAL DEGRADATION OF POLY(1-VINYLNAPHTHALENE) AND POLY(METHYL METHACRYLATE) BLENDS

A reversible photophysical degradation of P1VN/PMMA blends is observed at 77 K upon prolonged irradiation. In the dilute blends, the ratio of singlet excimer to monomer emission increases as exposure time increases. However, thermal annealing even below the glass transition temperature can restore the original ratio of singlet excimer to monomer. The photodegradation is also monitored by its effect on the fractal-like triplet exciton transport, i.e., via delayed fluorescence and phosphorescence time decays. It reduces the heterogeneity (fractional) exponent characterizing the exciton transport. However, these exponents still exhibit consistent dependence on chromophore concentration even as irradiation time varies. © 1990 American Chemical Society.