Dielectric studies of liquid crystals: the influence of molecular shape

One of the first applications of the molecular field theory developed by Maier and Saupe (Maier W.; Saupe, A. Z. Naturforsch. 1958, 13a, 564–566) was to the static dielectric properties of a nematic liquid crystal by Maier and Meier (Maier, W.; Meier, G. Z. Naturforsch. 1961, 16a, 262). Then, in a paper published in 1966 with G. Meier, (Meier, G.; Saupe, A. Mol. Cryst. 1966, 1, 515) Saupe developed a simple theory to explain the low-frequency dielectric relaxation observed in the nematic phase around 1 MHz, but absent in the isotropic phase, and indeed absent in all other isotropic molecular fluids. This paper reviews this work of Saupe and the subsequent development of the theory by Martin, Meier and Saupe (Martin, A.J.; Meier, G.; Saupe, A. Symp. Faraday Soc. 1971 , 5, 119), and then by others such as Nordio, Rigatti and Segre (Nordio, P.L.; Rigatti, G.; Segre, U. Mol. Phys. 1973, 25, 129). These theories described the effect of a nematic potential on the dipole relaxation times for a molecule, and prov...