Thermotropic reentrant isotropic symmetry and induced smectic antiferroelectricity in the ferroelectric nematic material RM734

• 成果类型: Article
• 署名作者: Chen, Xi; Shuai, Min; Zhong, Bingchen; Martinez, Vikina; Korblova, Eva; Glaser, Matthew A.; Maclennan, Joseph E.; Walba, David M.; Clark, Noel A.
• 署名单位: University of Colorado System; University of Colorado Boulder; University of Colorado System; University of Colorado Boulder
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11741
• DOI: 10.1073/pnas.2424917122
• 发表日期: 2025-04-22
• 关键词: liquid-crystals; modulated phases; cubic phase; nanostructure; breaking; field

摘要

We report a transition from the ferroelectric nematic liquid crystal (NF) phase to a lower-temperature, apolar fluid phase having reentrant isotropic symmetry (IR), in the liquid crystal compound RM734 doped with small concentrations of the ionic liquids 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) or 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI). Even a trace amount of ionic liquid dopant facilitates the kinetic pathway for the transition from the NF to the IR, enabling simple cooling to produce this isotropic fluid phase rather than resulting in immediate crystallization. The IR was also obtained in the absence of specific ionic liquid doping by appropriate temperature cycling in three distinct, as-synthesized-and-purified batches of RM734, two commercial and one from our laboratory. Ionic liquid doping also stabilizes the smectic ZA, an additional birefringent antiferroelectric phase having the director parallel to fluid smectic layers, significantly increasing its temperature range between the paraelectric and ferroelectric nematic phases with increasing BMIM concentration.