Ferroelectric Nematic Liquid Crystals

摘要：铁电向列是一种本质上由棒状分子组成的流体，这些分子自发地组织成具有宏观极性秩序的畴。最近这种液晶相的发现为探索和理解广泛软材料（包括聚合物、生物材料、液晶和胶体）中自发极化的外观创造了机会。铁电向列的极性特性使其具有许多新颖的应用，包括电光和非线性光学器件，并将导致向列液晶科学和应用的新发现。本项目为少数民族高中生提供了极好的本科研究参与和实习机会。技术摘要：铁电向列相（FN）是一种新的、基本上尚未开发的流体状态，它出现在液晶的传统向列相之下，首次在任何均匀的三维流体中结合了取向顺序和自发极化。估计的FN极化密度比许多固态铁电体大，其量级意味着向列分子偶极子几乎完美的极性排列。由于其大的自发极化，FN材料对施加的电场有一个简单、快速的定向响应，几乎给每一个向列效应和应用一个新的维度。一个广泛的、协调的分子设计、合成和物理表征的努力将继续进行，以表征铁电向列态，并逐步了解其纳米尺度的起源、新兴的介观性质和潜在的应用。实验方法包括电光研究、x射线散射、光学和SHG显微镜以及介电光谱，将用于表征FN分子组织、宏观结构和场响应动力学。连续体模型将被开发来描述一个新的向列弹性流体动力学体系，其中极化空间电荷稳定成为一个主要的参与者。该材料研究部（DMR）拨款支持铁电向列液晶的研究，该研究由数学和物理科学理事会DMR的凝聚态物理（CMP）项目资助。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。

Nontechnical Abstract:Ferroelectric nematics are fluids of essentially rod-shaped molecules that spontaneously organize into domains with macroscopic polar order. The recent discovery of this liquid crystal phase has created an opportunity to probe and understand the appearance of spontaneous polarization in a broad range of soft materials, including polymers, biomaterials, liquid crystals and colloids. The polar nature of the ferroelectric nematic makes it attractive for a host of novel applications, including electrooptical and non-linear optical devices, and will lead to new discoveries in the science and applications of nematic liquid crystals. This project offers excellent opportunities for undergraduate research participation and internships for minority high school students.Technical Abstract:The ferroelectric nematic (FN) is a new and essentially unexplored fluid state that occurs below the conventional nematic phase of liquid crystals, combining orientational order and spontaneous polarization for the first time in any homogeneous three-dimensional fluid. The estimated FN polarization density is larger than many solid state ferroelectrics, its magnitude implying almost perfect polar alignment of the nematic molecular dipoles. Because of their large spontaneous polarization, FN materials give a facile, rapid orientational response to applied electric fields, giving virtually every nematic effect and application a new dimension. A broad-based, coordinated effort of molecular design, synthesis, and physical characterization will be pursued to characterize the ferroelectric nematic state and to evolve an understanding of its nanoscale origins, emergent mesoscopic properties, and potential applications. Experimental methods including electro-optic studies, x-ray scattering, optical and SHG microscopy, and dielectric spectroscopy will be used to characterize FN molecular organization, macroscopic structure, and field response dynamics. Continuum modeling will be developed to describe a new regime of nematic elasto-hydrodynamics where polarization space charge stabilization becomes a dominant player.This Division of Materials Research (DMR) grant supports research to understand ferroelectric nematic liquid crystals with funding from the Condensed Matter Physics (CMP) program in DMR of the Mathematical and Physical Sciences Directorate.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.