Non-Debye segmental relaxation of poly-N-vinyl-carbazole in dilute solution

Abstract

Ultrasonic absorption measurements were carried out for poly-N-vinyl-carbazole in dilute 1,2-dichloro-ethane solution at frequencies from 1 to 50 MHz over a temperature range of 10–45°C with increments of 5°C under constant pressure. For the specific solution a single relaxation process was observed experimentally in the frequency range studied. The relaxation frequency of poly-N-vinyl-carbazole in 1,2-dichloro-ethane solution is comparable to the relaxation frequency observed in vinyl-type polymers despite the structural differences and the corresponding relaxation process is thermal in nature and assigned to the local segmental motions of some monomeric units. From the temperature dependence of the acoustic parameters we were able to estimate the thermodynamic parameters related to the segmental motion of the PVK polymer chains in solution. Furthermore, we performed molecular mechanics calculations on polymeric chains with a relatively low number of monomers to elucidate the mechanism behind the relaxation process and to establish the suggested local segmental motions of the polymer in 1,2-dichloro-ethane solution. The experimental and theoretical results have been compared and discussed in the context of relevant theories of the field.