Molecular mobility of diepoxy nematics studied by dielectric spectroscopy

The molecular mobility of four liquid crystalline epoxy compounds was studied by dielectric spectroscopy in a wide range of frequency (10−1–109 Hz). All the investigated materials form a nematic liquid crystalline phase at temperatures above 60 °C, one of them additionally exhibits a smectic A phase. Two of the compounds have molecules composed of a mesogen and two symmetric tails with eight alkyl groups each. Their properties were compared with the homologous pair having two alkyl groups in each tail. The length of the carbon chain influences the temperature range of the mesophase, which was also observed in this study. Characteristic relaxation processes were observed in the different mesophases. These processes were quantitatively analyzed and the estimated parameters were discussed in detail in dependence of the structure of the materials.