Composite stability and electro-optical properties of carbon nanotubes/5CB-based nematic hybrid liquid crystals

ABSTRACT

This study examined the impact of different concentrations of carbon nanotubes (CNTs) on five nematic hybrid liquid crystals (LCs) based on 5CB. Electro-optical properties of the composite were tested, and the interaction between CNTs and LCs was theoretically analysed by first principles. Experimental results showed the effect of CNTs on electro-optical properties of hybrid LCs depended on the groups contained in monomer LCs. LCs with polar groups at the end increased the dielectric anisotropy of the composite, while the impact of CNTs on hybrid LCs containing non-polar terminal monomers was the opposite. The same variation was reflected in splay elastic constants and clearing points. Meanwhile, dielectric anisotropy, splay elastic constant, and rotational viscosity coefficients all changed with CNTs doping concentrations, reflecting the order of binding stability between representative groups and CNTs, and the variation of threshold voltage and response time reflected the order of binding stability between LC molecules and CNTs, consistent with theoretical calculations. Conductivity tests showed the additive of CNTs increased the conductivity of the composite and revealed the impact of CNTs on threshold voltage. Dielectric tests showed the incorporation of CNTs increased dielectric real and imaginary parts in low-frequency regions and increased relaxation frequency in high-frequency regions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Nematic liquid crystal
• multi-walled carbon nanotubes
• electro-optical parameters
• non-covalent interaction
• first principles

Disclosure statement

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

Additional information

Funding

This research is supported by the Natural Science Foundation of Hebei Province of China [A2021209005, A2019202235] and; the Provincial Department of Education Program of Hebei Province of China [QN2021118].