Limonene as a chiral dopant for liquid crystals: Characterization and potential applications

The chiral molecule D(L)-Limonene was used to induce thermotropic cholesteric-liquid-crystal phases. A description of the methods used to identify and characterize the chiral nematic phase and its features will be given. D-Limonene was substituted for conventional synthesized chiral dopants in a twisted-nematic (TN) cell and a bistable cholesteric reflective cell and showed an improvement in the response time. Further analysis showed that D(L)-Limonene reduces the rotational viscosity of the mixture by a considerable amount. It may be considered as a "molecular lubricant." It is surprising how many more synthesized chiral molecules have been used as the liquid-crystal field moves forward in comparison to naturally occurring molecules. Despite the large number of synthesized molecules used as a chiral dopant, D(L)-Limonene, can be used as a dopant for making cholesteric phases having the advantage of being a naturally occurring substance, environmentally friendly, and with very low cost.