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

Leaw, W.L., Mamat, C.R., Triwahyono, S., Jalil, A.A., Bidin, N.
Journal of colloid and interface science 2016 v.483 pp. 41-48
electron paramagnetic resonance spectroscopy, gelation, gels, light intensity, light microscopy, light scattering, liquid crystals, micropores, scanning electron microscopy, stearic acid
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 48.0wt% cholesteryl stearate gelled 4-cyano-4′-pentylbiphenyl, the turbid appearance could be switched to a transparent state using a 5.0V alternating current. The response time was about 3.7μs. This liquid crystal physical gel has potential for use in light scattering electro-optical displays.