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Research Article

Fluorinated liquid crystals and their mixtures giving polar phases with enhanced low-temperature stability

, , , , , , & show all
Pages 558-568 | Received 05 Oct 2023, Accepted 12 Jan 2024, Published online: 25 Jan 2024
 

ABSTRACT

The fluid ferroelectrics, called ferroelectric nematics (NF), have recently become available by incorporating strong polarity into rod-shaped liquid crystal molecules. Its unprecedented electro-optic properties have created significant excitement in soft matter research. The further progression from the NF phase to the antiferroelectric smectic Z (SmZA) phase, and ultimately to the ferroelectric Smectic A (SmAF) phase, represents a remarkable journey in emerging polar liquid crystal states. Nevertheless, the limitation of NF liquid crystal materials remains one of the prominent obstacles to physical property optimization and optoelectronic device development. In this work, we synthesized a series of fluorinated liquid crystal molecules with large dipole moments and systematically investigated their phase behavior. We designed them with a similar fluorinated aromatic skeleton and varied the structures of the terminal group and bridging bond. We found that the dipole moment density and shape anisotropy significantly affect the phase behavior. Notably, diverse polar liquid crystal phases, including NF, SmZA, and SmAF were observed. Through a multi-component mixing strategy, we successfully achieved a much-expanded temperature window and improved low-temperature stability not only in the NF phase but also in the SmZA and SmAF phases.

GRAPHICAL ABSTRACT

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/10.1080/02678292.2024.2306309.

Additional information

Funding

This work is supported by National Key Research and Development Program of China [No. 2022YFA1405000], the National Natural Science Foundation of China [NSFC No. 52273292], the Recruitment Program of Guangdong [No. 2016ZT06C322], the International Science and Technology Cooperation Program of Guangdong province [No. 2022A0505050006] and the Fundamental Research Funds for the Central University [No. 2022ZYGXZR001].

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