Polymer networks to induce deformations and topological defects in liquid crystals

引起液晶变形和拓扑缺陷的聚合物网络

• 批准号: 2004532
• 负责人: Francesca Serra
• 金额: $ 44.76万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004532&HistoricalAwards=false
• 关键词: Polymer; networks; induce; deformations; topological

Non-technical Description:Liquid crystals are not only interesting for their role at the foundation of the 100-billion-dollar display industry. They are ideal materials to create soft structures that are controllable with external stimuli, and they provide a platform for physicists and chemists to address fundamental scientific questions. Unlike disordered molecules in common fluids, molecules in liquid crystals have some amount of order. Different types of liquid crystals have significant variability in terms of molecular structure and arrangement, which results in different mechanical and optical properties. Understanding the differences and the similarities between liquid crystal phases opens new paths to create not only the next generation of liquid crystal displays but also of a broader range of liquid crystal-based nanomaterials; furthermore, it helps answering fundamental questions regarding transitions between different states of matter. The goal of this research is to quantify the similarities and differences between liquid crystal phases by using polymers as mediators. Polymers can be dispersed in liquid crystals to create an “imprint” of the molecular order, which can then be transferred to a different liquid crystal. The goal is to devise a new classification method by measuring the compatibility of liquid crystal phases to accommodate distortions in the molecular ordering seen in other liquid crystal phases. The impact of this project extends beyond the physics community. Aligned networks of polymers are present in biological systems, and this project helps elucidate the role they have in tissues. Moreover, the broader goals of this project involve the creation of lightweight materials with customizable properties. In terms of societal impact, one goal is to involve young students and the general public through outreach events about liquid crystals, whose visual appeal makes them effective for illustrating science concepts. This project also aims to provide the basis for several undergraduate theses, including theses by under-represented minority students enrolled in a departmental bridge program in collaboration with Baltimore-area colleges. Technical Description:This research project uses polymer networks templated in liquid crystals to impose deformation on other liquid crystal phases. Templated polymer networks can be obtained by dispersing monomers in low concentration in liquid crystals. Once cross-linked, the polymers carry the memory of the alignment. If the liquid crystal is removed from the polymer network, the same network can be re-filled with another material, which will have to comply with the deformations imposed by the polymers. The project has various goals, which include (a) the creation of templated polymer networks with specific distortions, (b) the analysis of the same networks re-filled with different kinds of liquid crystals, and (c) the quantitative measure of compatibility between the distortions and the identification of a “distance” between phases that provides a new classification method of liquid crystal phases. Other project goals involve using aligned polymer networks for 4D printing or as lightweight material for applications in biology or energy storage. Characterization of the liquid crystals are performed with optical microscopy, combined with electron microscopy and small angle x-ray scattering.This Division of Materials Research (DMR) grant supports research to study phase structure and ordering in liquid crystals with funding from the Condensed Matter Physics (CMP) Program in DMR of the Mathematical and Physical Sciences (MPS) 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.

非技术描述：液晶之所以有趣，不仅仅是因为它在价值1000亿美元的显示产业中所扮演的基础角色。它们是创建可受外部刺激控制的软结构的理想材料，它们为物理学家和化学家提供了解决基本科学问题的平台。与普通液体中的无序分子不同，液晶中的分子有一定程度的有序。不同类型的液晶在分子结构和排列方面具有显著的差异性，从而导致不同的机械和光学性质。了解液晶相之间的差异和相似之处，不仅为创造下一代液晶显示器，而且为更广泛的液晶基纳米材料开辟了新的途径；此外，它有助于回答关于物质在不同状态之间转换的基本问题。本研究的目的是通过使用聚合物作为介质来量化液晶相之间的异同。聚合物可以分散在液晶中，形成分子顺序的“印记”，然后可以转移到不同的液晶中。目标是通过测量液晶相的相容性来设计一种新的分类方法，以适应在其他液晶相中看到的分子有序的扭曲。这个项目的影响超出了物理学界。聚合物的排列网络存在于生物系统中，该项目有助于阐明它们在组织中的作用。此外，该项目的更广泛目标包括创建具有可定制属性的轻质材料。在社会影响方面，一个目标是通过有关液晶的外展活动吸引年轻学生和公众，液晶的视觉吸引力使它们能够有效地说明科学概念。该项目还旨在为几篇本科论文提供基础，其中包括与巴尔的摩地区学院合作参加部门桥梁项目的少数族裔学生的论文。技术描述：本研究项目使用液晶模板化的聚合物网络对其他液晶相施加变形。通过在液晶中分散低浓度的单体，可以得到模板化的聚合物网络。一旦交联，聚合物就携带了排列的记忆。如果将液晶从聚合物网络中移除，则可以用另一种材料重新填充相同的网络，这种材料必须遵守聚合物施加的变形。该项目有多种目标，其中包括(a)创建具有特定畸变的模板化聚合物网络，(b)分析用不同种类的液晶重新填充的相同网络，以及(c)定量测量畸变之间的兼容性和识别相之间的“距离”，从而提供一种新的液晶相分类方法。其他项目目标包括使用排列的聚合物网络进行4D打印或作为轻质材料应用于生物或能源存储。利用光学显微镜，结合电子显微镜和小角度x射线散射对液晶进行了表征。该材料研究部（DMR）资助了由数学和物理科学（MPS）理事会DMR凝聚态物理（CMP）计划资助的研究，以研究液晶的相结构和有序。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。