Intermolecular excimer formation in poly(2-naphthyl methacrylate) solutions

Efficient intermolecular excimer emission is observed for solutions of poly(2-naphthyl methacrylate) and copolymers of 2-naphthyl methacrylate and methyl methacrylate, only above a critical concentration. From analysis of the dependence of this concentration upon the polymer molecular weight and the thermodynamic character of the solvent, it is concluded that the results cannot be explained only in terms of an excluded volume effect, and that the different behaviour for dilute and concentrated regions is mainly a consequence of a change in the factors which control the rate of intermolecular excimer formation. The efficient excimer formation in the concentrated solutions is attributed to the contribution of migration of the excited energy to the formation of the excimeric pair.