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Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

Leaw, Wai Loon and Mamat, Che Rozid and Triwahyono, Sugeng and Abdul Jalil, Aishah and Bidin, Noriah (2016) Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel. Materials Chemistry and Physics, 184 . pp. 197-202. ISSN 0254-0584

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Official URL: http://dx.doi.org/10.1016/j.matchemphys.2016.09.04...

Abstract

Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell.

Item Type:Article
Uncontrolled Keywords:liquid crystal physical gel, twisted nematic display
Subjects:Q Science > QD Chemistry
Divisions:Science
ID Code:69307
Deposited By: Siti Nor Hashidah Zakaria
Deposited On:22 Nov 2017 00:45
Last Modified:22 Nov 2017 00:45

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