Excimer Studies of Polymer Solutions Over the Entire Concentration Range

Abstract

Results of excimer fluorescence studies on solutions of polystyrene, polyethylene terephthalate and polybenzamide from dilute, semidilute and concentrated solutions and on the solid films have been discussed and summarized. For flexible chain polymers, a fractional power dependence of the excimer to monomer fluorescence intensity ratio on concentration in the semidilute region have been found to be a polymer effect resulting from a shrinkage of the coil dimension in solution with increasing concentration. This is true also in a $\theta$-solution. In very concentrated solutions and in the amorphous solid film of polyethylene terephthalate pronounced excimer fluorescence observed indicates the presence of local stacking of terephthaloyl chromophores during the process of condensed phase formation and some local parallel chain segment aggregation. For the rigid chain polybenzamide evidence for the stacking of the planar chromophores in going from a dilute solution to a nematic solution has been found in concentrated sulfuric acid solution by excimer fluorescence.