Influence of the length of end-group double bond substituents on the temperature change of phase transition in liquid crystals

ABSTRACT

A series of nematic liquid crystal (LC) monomers, containing a reactive group in the lateral substituent, were designed and synthesised through an organic synthesis reaction. Considerable changes were made to the properties of the liquid monomers by varying the terminal alkyl chain lengths. The molecular structures of the intermediates and the LC monomers were characterised by flourier infrared absorption spectrometry and proton nuclear magnetic resonance (¹H NMR) spectroscopy, leading to the identification of the target product. The phase transition temperatures of the LC monomers were observed and analysed using differential scanning calorimetry (DSC) and polarising optical microscopy (POM) with a hot stage. The two-way thermotropic liquid crystalline behaviour was observed during the heating process, providing insight into the effect of substituent changes on the phase transition temperature.

Graphical abstract

KEYWORDS:

• Liquid crystals
• double bond
• synthesis
• properties
• temperature

Acknowledgments

This work is financially supported by National Natural Science Foundation of China (Grant No.51403050), the Natural Science Foundation of Hebei Province, China (Grant No. E2015209274). We would like to thank Dr. Sui Baohua for assistance in obtaining some of the NMR spectra and Dr. Chen Ying for analysis of DSC and FTIR.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02678292.2024.2302495.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China (Grant No. 51403050), the Natural Science Foundation of Hebei Province, China (Grant No. E2015209274).