FLUORESCENCE FROM POLY(N-VINYLCARBAZOLE) IN UNIAXIALLY STRETCHED POLYMER-FILMS

Steady-state and time-resolved fluorescence properties of poly(N-vinyl carbazole) (PVCz) dispersed in a polystyrene (PS) cast film were studi ed under tensile loadings at room temperature. The excited monomer emi ssion of PVCz located around 350 nm decreased with increasing applied tensile strain from 0 to 0.8%. The strain enhanced the emission which was ascribed to the partial-overlap excimer of PVCz in a 360-430 nm re gion. The emission due to the full-overlap excimer of PVCz between 430 and 500 nm was unchanged by the action of the tensile loadings. The r atio of fluorescence intensities at 375 nm and 345 nm I-375/I-345 was proportional to the applied strain. The time-resolved fluorescence stu dy indicated that the lifetimes of the excited monomer and of the part ial-overlap excimer were not affected by the strain. The obtained resu lts mean that the strain applied to the PS matrix increases the partia l-overlap conformation of two adjacent carbazolyl chromophores in a PV Cz chain and suggest that PVCz is a useful probe for detecting residua l strains in polymer matrices. (C) 1997 John Wiley & Sons, Inc.