The fluorescent spectra of two series of sulfonated polyelectrolytes respectively labeled with dansyl and pyrenyl groups were determined as a function of volume fraction φ THF of THF in DMSO/THF mixed solvents. When φ THF 0.65, the maximum wavelength λ em and the intensity R F relative to that in DMSO for a band of dansylated samples, as well as I 1/I 3 for pyrene labeled samples varied slightly with increasing φ THF , indicating the capability of polyelectrolyte to maintain its chain solvation stable.As long as φ THF beyond 0.70, there was an abrupt drop in R F and λ em showing the sudden change in the chain solvation layer. I 1/I 3 decreased with an increase in the charge density of polyelectrolyte samples,suggesting the existence of aggregated structure even in pure DMSO.
