Dielectric Manifestation of the Liquid–Liquid Transition in Poly(n-Alkyl Methacrylates)

The dielectric study of samples from the poly(n-alkyl methacrylates) series has been realized. It has been performed by thermo-stimulated currents (TSC) and dynamic dielectric spectroscopy (DDS). TSC experiments revealed the existence of a dipolar relaxation mode above Tg. The fractional polarizations protocol allowed us to establish the narrow relaxation times distribution of this mode, and the associated behavior laws. We showed that this relaxation mode is dependant on the chain structure, in other words, the alkyl side chain length. DDS experiments also exhibited an additional relaxation mode. From the comparison of both sets of data, we assigned this relaxation to the dielectric manifestation of the liquid–liquid transition.