Local Chain Dynamics of Several Polymers in Θ Solvents Studied by the Fluorescence Depolarization Method

Abstract

The relaxation times of local motion for five kinds of polymers: cis-polyisoprene (cis-PI), polystyrene (PS), poly (α-methylstyrene)(PαMS), syndiotactic-poly (methyl methacrylate) (s-PMMA), and poly (N-vinylcarbazole) (PVCz) were measured in the Θ solvents by the fluorescence depolarization technique. The viscosity reduced relaxation time T_m/η was in the following order with the activation energy in the same order: cis-PI < PS < PαMS < PVCz < s-PMMA. The relaxation time and the activation energy depend on whether the polymer is either mono-substituted or di-substituted, the bulkiness of the substituents, and also the stereoregularity. It was found that T_g, is closely correlated with the local chain mobility obtained in dilute solution.