Straight-chain alkanediol derivatives leading to glassy cholesteric liquid crystals with visible reflection

ABSTRACT

Straight-chain alkanediols such as ethylene glycol are commonly found in our daily life as they are used to produce cosmetics, antifreezes, polyesters and polyurethanes. In this article, we report on the promising potential use of straight-chain alkanediols for rewritable full-colour imaging applications by the preparation of glassy cholesteric liquid crystals (G-CLCs). A series of straight-chain alkanediol derivatives possessing two cholesteryl groups through carbonate ester linkages (Cn-DiCh) showed thermotropic cholesteric liquid crystal phase with visible reflection. The thermally induced shifting ranges of reflection peaks were dependent on the central carbon chain length (n) of Cn-DiCh. Although the pristine Cn-DiCh showed narrow wavelength ranges of the reflection peaks by changing the temperature, we successfully prepared a mixture of two different kinds of Cn-DiCh at their equivalent weight ratio, which exhibited the reflection peak shift throughout a wide visible-wavelength range between 400 nm and 850 nm. Moreover, the binary mixtures of Cn-DiCh were rapidly cooled from the CLC temperatures to 0°C, whereupon the reflection colours could be preserved even at room temperature over 2 months. Such rapid cooling treatment enabled the straightforward preparation of solid-state G-CLCs with visible reflection characteristics, thereby leading to the applications of rewritable full-colour imaging media.

Graphical abstract

KEYWORDS:

• Alkanediols
• cholesteric liquid crystals
• visible reflection
• glassy
• full-colour imaging

Acknowledgments

All authors are grateful to helpful comments in the peer-review. Also, the authors would like to express sincere thanks to Mr. H. Onishi for his technical cooperation and advices concerning the XRD measurement and the Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This research was supported in part by the Ministry of Education, Science, Sports and Culture of Japan under the Grant-in-Aid for Scientific Research (B) (No. 25288103); Shorai Foundation for Science and Technology; NEXCO Group Companies’ Support Fund to Disaster Prevention Measures on Expressways.