Electromechanical Effects of Ferroelectric Nematic Liquid Crystals

非技术性说明：本项目的重点是研究最近发现的具有特殊性质的液晶，称为“铁电性液晶相”。铁电磁性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，这有点类似于某些材料（如铁）在没有外部介质的作用下如何变得具有磁性。此外，由于铁电向列相是流体，其永久电取向的方向可以用相对小的施加电压改变。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非常重要。该项目能够指导学生在物理，化学和材料科学的各个层次，通过麦克奈尔学者和本科生研究经验（REU）计划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的研究重点整合到实践中，公开访问教育材料。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，聚合物和位置有序液晶中进行过探索。该项目对铁电液晶（FNLC）的研究探索了这种耦合对极化和纳米结构的特定依赖性。互补挠曲电性研究阐明了弹性和电性能，并揭示了铁电性对挠曲电性的作用。该团队的材料合成工作扩展了具有优化特性的FNLC化合物库。部署各种实验技术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，和分子间的相关性，测试当前的模型预测的空间调制的极化方向的铁电相的一个重要特征。集体分子波动的详细表征阐明了极性极性相变的不同变体之间的相变的性质，并解释了反铁电，铁电和调制相的机电效应的变化。基本的实验结果不仅为软机器人和清洁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方向。该奖项反映了NSF的法定使命，通过使用基金会的智力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.