Liquid crystal physical gel formed by cholesteryl stearate for light scattering display material

• Main Authors: Leaw, W. L., Mamat, C. R., Triwahyono, S., Jalil, A. A., Bidin, N.
• Format: Article
• Published: Academic Press Inc. 2016
• Subjects: QD Chemistry
• Online Access: http://eprints.utm.my/id/eprint/71823/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989950900&doi=10.1016%2fj.jcis.2016.08.020&partnerID=40&md5=1770348798b1e76374e2a8363a770c48

A liquid crystal physical gel was prepared by the self-assembly of cholesteryl stearate in a nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical properties were tuned by varying the gelator concentration and the gelation conditions. Polarized optical microscopy revealed that cholesteric cholesteryl stearate induced chiral nematic phase in 4-cyano-4′-pentylbiphenyl during the gelation process. As a result, a plate-like gel structure consisting of spherical micropores was formed, as observed by scanning electron microscopy. Electron spin resonance spectroscopy showed that the liquid crystal director orientations in these macrophase-separated structures were massively randomised. For these reasons, the liquid crystal physical gel generated a strong light scattering effect. For 48.0 wt% cholesteryl stearate gelled 4-cyano-4′-pentylbiphenyl, the turbid appearance could be switched to a transparent state using a 5.0 V alternating current. The response time was about 3.7 μs. This liquid crystal physical gel has potential for use in light scattering electro-optical displays.