US-Ireland R&D Partnership: Structure-property relationships of new polar liquid crystalline phases through synthesis and characterization using a range of analytical techniques

美国-爱尔兰 R

• 批准号: 2211347
• 负责人: Michael Fisch
• 金额: $ 51.19万
• 依托单位: Kent State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2211347&HistoricalAwards=false
• 关键词: US; Ireland; R&D; Partnership; Structure

Nontechnical Explanation:The well-known liquid crystal display is generally based on molecules that are rod-like and may be modeled as a pencil sharpened at both ends. In the past 10-15 years there has been significant scientific interest in liquid crystals formed from bent molecules, modeled as a hockey stick, which also coincide with their mirror image. The study of molecules with these two structural properties has led to the discovery of new liquid crystalline phases with unique properties that are largely unexplored. The purpose of this research is to chemically synthesize new molecules that have these structures and exhibit these new phases and then study their physical properties with the dual goals of better understanding the relationships between molecular structure and liquid crystal properties and facilitating future applications of these materials as photonic, energy storage, and switching devices. These goals are accomplished by the pooling of the complementary expertise of a synthetic chemist, a physicist, and an engineer, from Northern Ireland, the US, and the Republic of Ireland respectively. This provides students and post-doctoral fellows a unique multidisciplinary and multinational environment for scientific, professional, and cultural enrichment through collaboration, scientific residencies in other Principal Investigator’s laboratories and the acquisition of skills that are not obtainable by working in a single laboratory. Technical Description:Current liquid crystal technologies are almost exclusively based on rod-like (calamitic) molecules that form nematic, and/or smectic phases. However, over the past 10-15 years there has been great interest in non-chiral molecules that are not rod-like. This led to the discovery of new nematic phases and corresponding nematic-nematic phase transitions. These new phases are called the twist-bend, the splay-bend, the splay, and the ferro nematic. These phases and their phase transitions and physical properties are a largely unexplored frontier. Molecules of this geometry sometimes form polar smectic phases, and should such phases be found; they too will be studied. The goal of this research is to synthesize and study the physical properties of new liquid crystalline materials that form from “bent” molecules with the objective of better understanding and advancing the relationship between molecular structure, the resulting liquid crystalline phases, and the physical and chemical properties of the resulting polar nematic and smectic mesophases. This is achieved through systematic synthesis of new mesogens that form the desired phases from bent core, bimesogen, and twisted core moieties; determination of liquid crystal phases and their transition temperatures; use of electro-optical and complementary spectroscopic techniques (x-ray scattering, Raman scattering, infrared, birefringence, wideband dielectric spectroscopy, and second harmonic generation) to investigate the structure and physical properties of these phases. Finally, test cells with well oriented liquid crystal molecules will be fabricated. These will be used to investigate the effect of various (electric, magnetic, surface anchoring, and flow) fields to investigate applications of these phases as well as to facilitate measurements of physical properties.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.

非技术解释：众所周知的液晶显示通常基于类似杆状的分子，可以建模为两端尖锐的铅笔。在过去的10 - 15年中，对由曲棍球棒建模的弯曲分子形成的液晶具有很大的科学兴趣，这也与镜像相吻合。具有这两种结构特性的分子的研究导致发现了新的液晶相具有独特特性的新液晶相。这项研究的目的是化学合成具有这些结构并揭露这些新阶段的新分子，然后以双重目标的双重目标研究其物理性能，即更好地了解分子结构与液晶特性之间的关系，并支持这些材料作为光子，能量存储和开关设备的未来应用。这些目标是通过分别来自北爱尔兰，美国和爱尔兰共和国的合成化学家，物理学家和工程师的完整专业知识来实现​​的。这为学生和博士后研究员提供了一个独特的多学科和跨国环境，可通过合作，其他主要研究者实验室的科学住宅以及在单个实验室工作而无法获得的技能，从而为科学，专业和文化丰富。技术描述：当前的液晶技术几乎完全基于形成列表和/或近晶相的杆状（CALAMITIC）分子。但是，在过去的10 - 15年中，人们对不像杆状的非手续分子引起了极大的兴趣。这导致发现了新的列阶段和相应的列神经相变。这些新阶段称为弯曲，弯曲，splay和ferro nematic。这些阶段及其相变和物理特性在很大程度上是意外的边界。这种几何形状的分子有时会形成极性近晶相，应发现这些阶段。他们也将被研究。这项研究的目的是综合和研究由“弯曲”分子形成的新液晶材料的物理特性，目的是更好地理解和发展这种关系。在分子结构，产生的液晶相，以及所得的极性列列和近晶型中发育相的物理和化学特性之间。这是通过系统的合成新的中质质量来实现的，这些新中质成分形成了弯曲核，双列原生和扭曲的核心部分的所需阶段。确定液晶相及其过渡温度；使用电流和互补的光谱技术（X射线散射，拉曼散射，红外，双发性光谱，宽带饮食光谱和第二次谐波生成）来研究这些阶段的结构和物理特性。最后，将制造具有定向液晶分子的测试细胞。这些将用于研究各种（电气，磁，表面锚定和流动）场的影响，以研究这些阶段的应用以及促进物理特性的测量。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来通过评估来支持的。