MICROENVIRONMENTS IN POLY(ETHYLENE-TEREPHTHALATE) FILM REVEALED BY MEANS OF FLUORESCENCE MEASUREMENTS

The fluorescence behaviour of poly(ethylene terephthalate) (PET) films prepared by using a spin-casting method was measured. The wavelength of the fluorescence peak was found to be dependent on the casting temp erature, T-cast. This fluorescence is neither from a ground state dime r nor from an excimer. It is the redshifted fluorescence of either the phenylene group or the phenylene exciplex due to interactions involvi ng some contributions of charge-transfer stabilization among phenylene and carbonyl groups and/or phenylene groups. Both d.s.c. and i.r. mea surements clearly showed that the fluorescence reflects whether the ma in-chain phenylene ring of PET is in the crystal region or in the amor phous region. Copyright (C) 1996 Elsevier Science Ltd.