Steric Frustration at the Nanoscale: Self-Assembly, Chirality, and Fluctuations

纳米尺度的空间挫败：自组装、手性和涨落

• 批准号: 1710711
• 负责人: Noel Clark
• 金额: $ 55万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-15 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1710711&HistoricalAwards=false
• 关键词: Steric; Frustration; Nanoscale; Self; Assembly

NONTECHNICAL ABSTRACTThe packing of odd-shaped three dimensional objects can lead to steric frustration, meaning that it's hard to fill space. If the objects are molecules, however, thermal agitation samples all of the packing possibilities, either finding unexpected new arrangements or remaining disorganized. A recently discovered example of this is the heliconical nematic phase, a liquid in which banana-shaped molecules fill space by arranging themselves into molecular-scale helical structures. In this project bent molecules will be designed and synthesized and their phase behavior studied with the goal of exploring the geometrical and statistical principles that govern how such steric frustration is accommodated in materials. The resulting design criteria would have wide ranging applications in the development of new materials based on the control and use of steric frustration. This project will provide its junior scientists (undergraduate student, graduate student, and postdoctoral researchers) with opportunities to participate in broadly interdisciplinary research in an exciting area of soft materials science. TECHNICAL ABSTRACTRod-shaped molecules form nematic liquid crystal phases, three dimensional fluids in which steric packing of rods induces long-range orientational order in thermal equilibrium. But introducing a simple chemical change to make the rods bent in shape produces an exotic new (heliconical nematic) phase in which the molecules spontaneously organize into chiral helical lattices of varying molecular orientation and nanoscale periodicity. The project hypothesis is that these distinctive new structures are a result of steric frustration: the bent molecular shape creates pockets of space which are difficult to fill, thereby attracting the most strongly fluctuating molecular sub-components. This newly formulated organizing principle will be explored in a broad-based, coordinated program of molecular design, chemical synthesis, physical characterization, and computer simulation of heliconical nematic phases. In particular, resonant soft x-ray scattering will be used to characterize their nanoscale orientational structure, and will be extended to probe molecular orientational fluctuations at the nanoscale. What is learned will be applied to a variety of soft matter systems, including liquid crystals, polymers and nanofabrications, with the intention of creating broadly useful, powerful means of probing and understanding nanoscale molecular orientational dynamics. The strong collective nanoscale chirality of the heliconical nematic phase makes it attractive for application in separation of enantiomers of chiral guest molecules, and as a templating medium for asymmetric synthesis. These applications of the heliconical nematic phase will be explored.

非技术性摘要 奇怪形状的三维物体的堆积可能会导致空间挫败，这意味着很难填充空间。 然而，如果物体是分子，热搅拌会对所有堆积可能性进行采样，要么发现意想不到的新排列，要么保持混乱状态。 最近发现的一个例子是螺旋向列相，这是一种液体，其中香蕉形分子通过将自身排列成分子级螺旋结构来填充空间。 在该项目中，将设计和合成弯曲分子，并研究它们的相行为，目的是探索控制材料中如何适应这种空间挫败的几何和统计原理。 由此产生的设计标准将在基于空间挫败的控制和使用的新材料的开发中具有广泛的应用。 该项目将为青年科学家（本科生、研究生和博士后研究人员）提供参与软材料科学这一令人兴奋的领域的广泛跨学科研究的机会。 技术摘要棒状分子形成向列液晶相，这是一种三维流体，其中棒的空间堆积在热平衡中引起长程取向顺序。 但是引入简单的化学变化使杆弯曲形状会产生一种奇特的新相（螺旋向列），其中分子自发组织成不同分子取向和纳米级周期性的手性螺旋晶格。 该项目的假设是，这些独特的新结构是空间挫败的结果：弯曲的分子形状产生了难以填充的空间袋，从而吸引了波动最强烈的分子子成分。 这种新制定的组织原则将在分子设计、化学合成、物理表征和螺旋向列相计算机模拟等基础广泛的协调程序中进行探索。 特别是，共振软X射线散射将用于表征其纳米级取向结构，并将扩展到探测纳米级分子取向波动。 所学到的知识将应用于各种软物质系统，包括液晶、聚合物和纳米加工，旨在创建广泛有用、强大的手段来探测和理解纳米级分子取向动力学。螺旋向列相的强集体纳米级手性使其在手性客体分子对映体的分离以及作为不对称合成的模板介质中的应用具有吸引力。将探索螺旋向列相的这些应用。

项目成果

Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase

扭转弯曲向列液晶相的纳米限制螺旋结构

• DOI: 10.1080/02678292.2018.1508770
• 发表时间: 2018-09
• 期刊: Liquid Crystals
• 影响因子: 2.2
• 作者: You, Ra;Park, Wongi;Carlson, Eric;Ryu, Seong Ho;Shin, Min Jeong;Guzman, Edward;Ahn, Hyungju;Shin, Tae Joo;Walba, David M.;Clark, Noel A.;et al
• 通讯作者: et al

Polar in-plane surface orientation of a ferroelectric nematic liquid crystal: Polar monodomains and twisted state electro-optics

铁电向列液晶的极性面内取向：极性单畴和扭曲态电光

• DOI: 10.1073/pnas.2104092118
• 发表时间: 2020-12-30
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Xi Chen;Eva D Korblova;M. Glaser;J. Maclennan;D. Walba;N. Clark
• 通讯作者: N. Clark

Precision adiabatic scanning calorimetry of a nematic – ferroelectric nematic phase transition

向列相变的精密绝热扫描量热法 - 铁电向列相变

• DOI: 10.1080/02678292.2021.2007550
• 发表时间: 2021-12
• 期刊: Liquid Crystals
• 影响因子: 2.2
• 作者: Thoen, Jan;Korblova, Eva;Walba, David M.;Clark, Noel A.;Glorieux, Christ
• 通讯作者: Glorieux, Christ

Surface alignment of ferroelectric nematic liquid crystals

铁电向列液晶的表面排列

• DOI: 10.1039/d1sm00734c
• 发表时间: 2021-09
• 期刊: Soft Matter
• 影响因子: 3.4
• 作者: Caimi, Federico;Nava, Giovanni;Barboza, Raouf;Clark, Noel A.;Korblova, Eva;Walba, David M.;Bellini, Tommaso;Lucchetti, Liana
• 通讯作者: Lucchetti, Liana

First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics

热致向列液晶中铁电性的第一原理实验演示：极性域和引人注目的电光

• DOI: 10.1073/pnas.2002290117
• 发表时间: 2020-06
• 期刊: Proceedings of the National Academy of Sciences
• 作者: Chen, Xi;Korblova, Eva;Dong, Dengpan;Wei, Xiaoyu;Shao, Renfan;Radzihovsky, Leo;Glaser, Matthew A.;Maclennan, Joseph E.;Bedrov, Dmitry;Walba, David M.;et al
• 通讯作者: et al