Electromechanical Effects of Ferroelectric Nematic Liquid Crystals

铁电向列液晶的机电效应

• 批准号: 2210083
• 负责人: Antal Jakli
• 金额: $ 83.18万
• 依托单位: Kent State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210083&HistoricalAwards=false
• 关键词: Electromechanical; Effects; Ferroelectric; Nematic; Liquid

Non-Technical Description:This project focuses on investigating liquid crystals which exhibit a recently discovered special property called “ferroelectric nematic phase”. Ferroelectric nematic materials are remarkable in that even though they carry no net electric charge, they generate a spontaneous electric field, somewhat analogously to how certain materials such as iron become magnetic without the action of an external agent. Moreover, because ferroelectric nematics are fluid, the direction of their permanent electric orientation can be altered with a relatively small applied voltage. These properties make ferroelectric neumatic materials very attractive for new technological solutions for motion-control and energy conversion, which are important in applications ranging from soft robotics to green electricity generation. The project enables mentoring students at all levels in physics, chemistry and materials science, with a special focus on under-represented groups via the McNair Scholar and Research Experience for Undergraduates (REU) programs. It provides young scientists with interdisciplinary training that enable them to secure productive careers in cutting-edge STEM enterprise. An additional priority is the integration of highlights of the team’s research into hands-on, publicly accessible educational materials.Technical Description:Linear electromechanical coupling is an inherent property of ferroelectric materials, but has previously been explored only in crystals, polymers, and positionally ordered liquid crystals. The project’s research on ferroelectric nematic liquid crystals (FNLCs) explores the specific dependence of this coupling on both polarization and nanostructure. Complementary flexoelectricity studies illuminate the elastic and electric properties and reveal the role of ferroelectricity on flexoelectricity. The team’s materials’ synthesis effort furnishes an expanding library of FNLC compounds with optimized properties. Various experimental techniques are deployed to measure key material parameters, including ferroelectric polarization, dielectric constants, elastic constants, orientational viscosities, and intermolecular correlations that test current models predicting spatial modulation of the polarization orientation as an important feature of the ferroelectric phase. Detailed characterization of the collective molecular fluctuations elucidates the nature of phase transitions between different variants of polar nematic phases and explains variations of the electromechanical effects in antiferroelectric, ferroelectric, and modulated phases. The basic experimental results guide the way to new, comprehensive microscopic theories in addition to providing pathways to potential applications in emerging technologies such as soft robotics and clean electric energy generation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：这个项目主要研究最近发现的一种特殊性质的液晶，称为“铁电向列相”。铁电向列型材料的显著之处在于，即使它们不携带净电荷，它们也会产生自发电场，这在某种程度上类似于某些材料，如铁，在没有外部介质的作用下变得有磁性。此外，由于铁电向列相是流体，其永久电取向的方向可以在相对较小的外加电压下改变。这些特性使铁电气动材料对运动控制和能量转换的新技术解决方案非常有吸引力，这些技术解决方案在从软机器人到绿色发电的各种应用中都非常重要。该项目通过麦克奈尔奖学金和本科生研究经验(REU)计划，对物理、化学和材料科学方面的所有级别的学生进行指导，特别关注代表性不足的群体。它为年轻科学家提供跨学科的培训，使他们能够在尖端的STEM企业中获得富有成效的职业生涯。技术描述：线性机电耦合是铁电材料的固有属性，但以前只在晶体、聚合物和位置有序的液晶中进行探索。该项目对铁电向列相液晶(FNLC)的研究探索了这种耦合对极化和纳米结构的具体依赖。互补的挠曲电学研究阐明了弹性和电学性质，并揭示了铁电对挠曲电学的作用。该团队的材料合成工作提供了一个扩大的FNLC化合物库，具有优化的性能。各种实验技术被用来测量关键的材料参数，包括铁电极化、介电常数、弹性常数、取向粘度和分子间关联，这些测试电流模型预测极化方向的空间调制是铁电相的重要特征。集体分子涨落的详细表征阐明了极性向列相不同变体之间相变的本质，并解释了反铁电相、铁电相和调制相中机电效应的变化。基本实验结果不仅为软机器人和清洁电力发电等新兴技术的潜在应用提供了途径，还为新的、全面的微观理论指明了道路。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Ferroelectric nematic droplets in their isotropic melt

各向同性熔体中的铁电向列相液滴

• DOI: 10.1039/d2sm01395a
• 发表时间: 2023
• 期刊: Soft Matter
• 影响因子: 3.4
• 作者: Perera, Kelum;Saha, Rony;Nepal, Pawan;Dharmarathna, Rohan;Hossain, Md Sakhawat;Mostafa, Md;Adaka, Alex;Waroquet, Ronan;Twieg, Robert J.;Jákli, Antal
• 通讯作者: Jákli, Antal