Synthesis and properties of liquid crystal monomers containing a reactive group in the lateral substituent

ABSTRACT

A series of nematic liquid crystal (LC) monomers containing a reactive group (double bonds) in the lateral substituent was designed and synthesised. Length of the lateral substituted groups that have one double bond varied from 1 to 4 methylene units. Length of the terminal substituted groups varied from 2 to 5 methylene units. The molecular structures of the intermediates and the LC monomers were characterised by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and nuclear magnetic resonance (NMR) spectroscopy. The thermal phase behaviour of the monomers was investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM) coupled with hot stage. Some molecules (V₁₅, V₂₅) with high aspect ratio exhibit enantiotropic nematic mesophase. The other compounds (V₁₂, V₂₂, V₄₂, V₄₃) show monotropic nematic mesophase during cooling. The relationship between the structure and mesomorphic property is also discussed.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal
• reactive group
• properties
• synthesis

Acknowledgements

We thank Dr. Sui Baohua for assistance in obtaining some of the NMR spectra and Dr. Chen Ying for analysis of DSC and FT-IR.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is financially supported by National Natural Science Foundation of China [grant number 51403050]; the Natural Science Foundation of Hebei Province, China [grant number E2015209274]; and the Tangshan Science and Technology Program, China [grant number 14130273a].