Dielectric Behavior of Poly(methyl methacrylate)s in Dilute Solutions

Abstract

Dielectric measurements were carried out on dilute solutions of isotactic and syndiotactic poly(methyl methacrylate)s in toluene and dioxane in the frequency range of 1—150 MHz over a wide range of temperature. A symmetrical dielectric loss curve was observed for each solution. The dielectric relaxation behavior of these two types of poly(methyl methacrylate)s was not much affected by the solvent viscosity. It is suggested that the dipole attached to a flexible side-chain performs a frictionless motion across a single potential barrier arising from intramolecular interactions between chain segments. The relaxation time calculated by using the Kramers rate constant for small friction is in close agreement with that observed. This agreement indicates that the motional unit involved in the relaxation process is fairly small. It is shown that the distribution of relaxation times and its temperature dependence can be well interpreted in terms of the equation presented by Frohlich.