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器通常基于棒状分子，可以将其建模为两端削尖的铅笔。在过去的 10-15 年中，人们对由液晶形成的液晶产生了浓厚的科学兴趣。弯曲的分子，被建模为曲棍球棒，这也与它们的镜像一致。对具有这两种结构特性的分子的研究导致发现了具有很大程度上未被探索的独特特性的新液晶相。到化学合成具有这些结构并表现出这些新相的新分子，然后研究它们的物理性质，其双重目标是更好地理解分子结构和液晶性质之间的关系，并促进这些材料在光子、能量存储和开关等方面的未来应用这些目标是通过汇集分别来自北爱尔兰、美国和爱尔兰共和国的合成化学家、物理学家和工程师的互补专业知识来实现​​的，这为学生和博士后研究员提供了独特的多学科。和跨国环境的科学，通过合作、在其他首席研究员实验室进行科学驻留以及在单个实验室工作中获得显着的技能来丰富专业和文化。 技术描述：当前的液晶技术几乎完全是基于棒状（棒状）分子获得的。然而，在过去的 10-15 年里，人们对非棒状的非手性分子产生了极大的兴趣，这导致了新的向列相的发现。这些新相称为扭曲弯曲、张开弯曲、张开和铁向列相，这些相及其相变和物理性质是该分子的一个很大程度上未探索的领域。几何形状有时会形成极性近晶相，如果发现这种相，这项研究的目标是合成和研究由此形成的新型液晶材料的物理性质。 “弯曲”分子的目的是更好地理解和推进分子结构、所得液晶相以及所得极性向列相和近晶中间相的物理和化学性质之间的关系，这是通过系统合成形成的新介晶来实现的。弯曲核、双介晶和扭曲核部分的所需相；使用电光和互补光谱技术（X 射线散射、拉曼散射、红外、双折射、宽带介电光谱和二次谐波产生）来研究这些相的结构和物理性质，最后，将制造具有良好取向的液晶分子的测试单元，这些将用于研究各种（电）的影响。 、磁性、表面锚定和流动）研究这些相的应用并促进物理特性的测量。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查进行评估，被认为值得支持标准。