Molecular Twisting Power of Cholesteryl Propionate, Nonanoate and Myristate

Abstract

We have measured the pitch of cholesteryl propionate-nonanoate mixture at different weight ratio for various temperature. The pitch of ternary mixture, cholesteryl propionate, nonanoate and myristate, was also measured as a function of temperature and concentration of cholesteryl myristate when the weight ratio of propionate and nonanoate is kept equal. The molar twisting power (p) was calculated by employing Bak and Labes' equation and the relation between twisting power and temperatures is found to be linear for cholesteryl propionate, nonanoate and myristate in the temperature range away from transitions.For the mixture with smectic mesophase the temperature coefficient of the pitch is anomalous. The v (critical exponent describing the divergence of the smectic correlation length) for cholesteryl nonanoate is found to be 0.611 which is in excellent agreement with de Gennes' prediction. I NTR 0 DU CTlO NIt is well known that the pitch of cholesterics can be changed by pressure, temperature and concentration. In the binary mixture of the cholesteric liquid crystal, the relation between pitch, temperature and concentration has been investigated by many auth01-s.'~~ Chen and Chou8 also had calculated the molar twisting power of cholesteryl propionate and acetate by using the equation derived by Bak and Labes. They found that the molar twisting power is linear in temperature for the temperature range which is away from the transitions. The dependence of pitch on concentration had been studied theoretically by many people.9P13 Bak

Combinatorial Approach for the Rapid Determination of Thermochromic Behavior of Binary and Ternary Cholesteric Liquid Crystalline Mixtures

“…Previous studies have explored the transitional and color play behavior of simple binary or ternary cholesteric mixtures. − However, the disparate nature of the information and the lack of extensive experimental trials on how incremental compositional changes within mixtures containing two or more components can affect the overall thermochromic behavior of those mixtures led to further investigation of this relationship. Ultimately, the identification of compositions appropriate for use as thermochromics across specific and defined temperatures ranges has been achieved.…”