Electromechanical Effects of Ferroelectric Nematic Liquid Crystals

非技术描述：本项目重点研究最近发现的具有“铁电向列相”特性的液晶。铁电向列材料的非凡之处在于，即使它们不携带净电荷，它们也会产生自发电场，这有点类似于某些材料（如铁）在没有外部介质作用的情况下变得磁性。此外，由于铁电向列是流体，它们的永久电取向的方向可以用一个相对较小的施加电压来改变。这些特性使得铁电气动材料对于运动控制和能量转换的新技术解决方案非常有吸引力，这在从软机器人到绿色发电的应用中都很重要。该项目能够指导物理、化学和材料科学各个层次的学生，并通过McNair本科生学者和研究经验（REU）项目特别关注代表性不足的群体。它为年轻科学家提供跨学科培训，使他们能够在尖端的STEM企业中获得富有成效的职业生涯。另一个优先事项是将团队研究的重点整合到实际操作的、可公开访问的教育材料中。技术描述：线性机电耦合是铁电材料的固有特性，但以前只在晶体、聚合物和位置有序液晶中进行了探索。该项目对铁电向列液晶（FNLCs）的研究探索了这种耦合对极化和纳米结构的特定依赖。互补挠性研究阐明了材料的弹性和电性，揭示了铁电性对挠性的影响。该团队的材料合成工作提供了一个不断扩大的具有优化性能的FNLC化合物库。采用各种实验技术来测量关键材料参数，包括铁电极化、介电常数、弹性常数、取向粘度和分子间相关性，以测试预测极化方向空间调制作为铁电相重要特征的电流模型。对集体分子波动的详细描述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、铁电和调制相中机电效应的变化。基本的实验结果为新的、全面的微观理论提供了指导，并为软机器人和清洁能源发电等新兴技术的潜在应用提供了途径。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.