RUI: Thermoreversable hydrogen bonding in mesogenic assembly: enhancing mesogen structure, stability and formation

非技术总结：液晶（lc）存在于所有有数字显示的设备中：手机、笔记本电脑和平板电脑。它们是世界上最重要的光学活性分子之一。当被称为中原的异形分子排列成液体时，液晶相就形成了。通常认为LC相具有非常微妙的结构，少量的结构或物理缺陷可以破坏它。液晶相自我修复或愈合的能力对于理解这些分子在不利条件下如何排列是非常重要的。该项目由美国国家科学基金会材料研究部固态与材料化学项目资助，研究了液晶网络的新概念，该网络能够愈合和修复可能发生的任何结构损伤。通过改变液晶结构中分子键的类型，首席研究员和他的团队开发了一种新方法，如果化学键被破坏，液晶网络可以重新形成/自我修复。除了它的科学影响，该项目加强了研究基础设施，并支持威斯康星大学欧克莱尔分校的人力资源开发。威斯康星大学欧克莱尔分校是一所低成本的公立大学，有着悠久的本科生/教师研究合作的传统。几乎一半的学生是低收入的第一代学生，大约60%是女性，这两种群体在科学界的代表性都不足。该研究项目通过对先进设备的亲身体验，极大地促进了学生的训练和智力发展，并为学生提供了在国家会议上展示其研究成果的机会。技术概述：利用非共价相互作用组装液晶材料提供了许多有趣的特性，包括活体聚合物体系和介质自愈和修复宏观结构缺陷的能力。液晶网络是一个受到相当关注的领域，因为材料能够将介晶的顺序与材料的弹性耦合起来。热可逆组件在液晶网络中的应用是一个相对未被研究的领域。将氢键的愈合性和可逆性与交联介生系统的特性结合起来的能力可以生产出具有非常有趣的特性和性能的材料。该项目由美国国家科学基金会材料研究部固态和材料化学项目资助，能够合成一系列液晶前体网络剂，其中氢键受体与中心碳距离较远。通过改变分子的功能，从组装点到中心碳的距离（增加链长）以及氢键受体的大小和刚性，研究了这种远端交联对氢键液晶聚合物和网络形成能力的影响。一项推论研究确定了使用2-吡啶酮功能的双氢键组件来创建液晶聚合物的效果。利用光谱、x射线和热分析技术研究了一系列具有可变结构和间隔长度的2-吡啶酮芳香酯结构对中间相稳定性和结构的影响。这些新型液晶系统的创建为中间相在不利的、受限的（网络）条件下稳定的能力提供了有价值的见解，以及对通过多个氢键组装的系统的理解。赋予液晶系统新的特性提供了新的材料，将共价体的稳定性与氢键结合链结构的稳定性和愈合能力相结合。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。

Non-technical Summary:Liquid crystals (LCs) are in everything that has a digital display: phones, laptops and tablets. They are amongst the most important optically active molecules in the world. Liquid crystalline phases are formed when shaped molecules, called mesogens, align as a liquid. Common wisdom has been that LC phases have a very delicate structure and miniscule amounts of structural or physical defects can destroy it. The ability of a liquid crystalline phase to self-repair or heal would be very significant to understanding how these molecules align under adverse conditions. This project, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, investigates new concepts of liquid crystalline networks that are capable of healing and repairing any structural damage that may occur. By changing the type of molecular bonding in the liquid crystal structures, the principle investigator and his group develop a new approach that allows liquid crystal networks to re-form/self-repair, if chemical bonds are broken. Beyond its scientific impact this project enhances the research infrastructure and support human resource development at the University of Wisconsin-Eau Claire. The University of Wisconsin-Eau Claire is a low-cost public institution that has a long-established tradition of strong undergraduate/faculty research collaboration. Almost half of the student body are low-income, first generation students, and about 60% are female, both of which are underrepresented in the scientific communities. This research project greatly enhances student training and intellectual development through hands-on experience with sophisticated equipment and offers the students opportunities to present their findings at national meetings. Technical Summary:The assembly of liquid crystalline materials using non-covalent interactions offers many interesting features involving living polymeric systems and the ability of the mesogens to self-heal and repair macroscale structural defects. Liquid crystalline networks are an area that has received considerable attention due to the ability of the materials to couple the order of the mesogenic directors to the elasticity of the materials. The application of thermoreversible assemblies to liquid crystalline networks is a relatively unexamined area. The ability to combine the healing and reversibility of the hydrogen bond with the characteristics of a crosslinked mesogenic system could produce materials with very intriguing characteristics and properties. This project, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, enables the synthesis of a series of liquid crystal precursor networking agents in which the hydrogen bond acceptor is distanced from the central carbon. By varying the functionality of the molecule, the distance from the assembly point to the central carbon (increasing chain length) and the size and rigidity of the hydrogen bond acceptor, the effect of this distal crosslinking on the ability of a hydrogen-bonded liquid crystalline polymer and network to form is investigated. A corollary study determines the effects of using the double hydrogen bond assemblies of the 2-pyridone functionality to create liquid crystalline polymers. In these a series of 2-pyridone aromatic ester tectons are created with variable structure and spacer lengths to determine the effect on mesophase stability and structure, which are studied using spectroscopic, X-ray and thermal analytical techniques. The creation of these new liquid crystalline systems provides valuable insight into the ability of a mesophase to stabilize in unfavorable, constrained (networked) conditions, as well as an understanding of systems assembled through multiple hydrogen bond assemblies. Imparting new characteristics to liquid crystalline systems provides new materials, combining the stabilities of covalent species with the lability and healing capabilities of hydrogen bonded associative chain structures.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.