An effect of chiral dopants on mesomorphic and electro-optical properties of ferroelectric smectic mixture

ABSTRACT

The aim of the presented research was an assessment of an effect of chiral dopants on the physical and electro-optical properties of a ferroelectric smectic mixture which is a key factor of elaboration of working ferroelectric liquid crystal (FLC) mixtures of tailored properties, especially with the tilt angle $\theta$value near 22.5° in a broad temperature range. Testing FLC mixtures were prepared using the common pyrimidine-based parent mixture F4 doped with three different chiral dopants. The thermal characteristic of the optical tilt angle ${\theta }_{OPT}$, tilt angle calculated by means of X-ray diffraction method ${\theta }_{XRD}$, spontaneous polarisation $P_s$ and layer spacing $d$ of obtained FLC mixtures were studied. Based on the above measurements and computer calculations, the relationship between spontaneous polarisation $P_s$ and tilt angle ${\theta }_{OPT}$ was discussed. Electro-optical performance of the Surface Stabilised Ferroelectric Liquid Crystal (SSFLC) structures was observed. The relation between the molecular properties of chiral dopants and the electro-optical and physical properties of obtained FLC mixtures is considered in frames of the extended microscopic model of the spontaneous polarisation in FLCs.

Graphical abstract

KEYWORDS:

• Induced chirality
• pyrimidine-based smectic
• surface stabilised ferroelectric liquid crystal (SSFLC)
• spontaneous polarisation - tilt coupling
• SmC*-SmA* phase transition

Acknowledgments

The work was partially supported by the Ministry of National Defence Republic of Poland Program - Research Grant MUT Project 13-995 and MUT University Grant RMN 08-691.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Wojskowa Akademia Techniczna [RMN 08-691]; Ministry of National Defence Republic of Poland [Project 13-995].