Thermal and optical properties of amphitropic liquid crystals derived from cholesterol and cinnamic acid. Issue 4 (16th March 2021)

• Record Type: Journal Article
• Authors: Hung, Yi-Hua; Liu, Chun-Yen; Chen, Wei-Chieh; Liu, Jui-Hsiang
• Is Part Of: Liquid crystals. Volume 48:Issue 4(2021)
• Page Start: 542
• Page End: 554
• Publication Date: 2021-03-16
• Subjects: Cholesteric liquid crystals -- lyotropic -- thermotropic -- amphitropic -- Bragg reflection; Liquid crystals -- Periodicals; 548.905
• DOI: 10.1080/02678292.2020.1795737
• Languages: English
• ISSNs: 0267-8292

Abstract

ABSTRACT: In this paper, we firstly demonstrate the synthesis of chiral amphitropic liquid crystals derived from cholesterol as well as their thermal and optical properties. Chiral monomeric cholesteryl-4-(6-acryloyloxyhexyloxy) cinnamate (CCM) derived from cholesterol and cinnamic acid has been synthesised showing amphitropic liquid crystal phases. The synthesised CCM exhibits oily streak textures under a polarised optical microscope (POM), corresponding to cholesteric liquid crystal phase formed after heating over 120°C and after being treated with organic solvents such as dichloromethane, chloroform, tetrahydrofuran and toluene. Both the thermotropic and lyotropic cholesteric liquid crystals exhibit selective light reflection, and the wavelength of the reflected light falls in the visible light region showing colourful appearances. The results suggest that CCM could be used for the development of sensors for both temperature and solvents. Homopolymer (Poly-CCM) was synthesised via free radical polymerisation. The synthesised polymer did not exhibit any mesomorphic behaviour either by heating or being treated with solvents. These results indicate that the long chain hydrocarbons and sidechains of CCM were disturbed and restricted after polymerisation leading to the loss of liquid crystalline properties. However, cholesteric construction of monomeric CCM was fixed via UV-polymerisation. The synthesised Poly-CCM film shows Bragg reflection significantly. Graphical abstract: