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，不仅仅是因为它们在千亿美元显示器产业的基础上扮演的角色。它们是创造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。与普通流体中的无序分子不同，液晶中的分子具有一定的有序性。不同类型的液晶在分子结构和排列上有很大的差异，这导致了不同的力学和光学性质。了解液晶之间的差异和相似之处不仅为创造下一代液晶显示器开辟了新的途径，也为创造更广泛的基于液晶的纳米材料开辟了新的途径；此外，它还有助于回答关于不同物质状态之间的跃迁的基本问题。这项研究的目的是通过使用聚合物作为介体来量化液晶相之间的异同。聚合物可以分散在液晶中，形成分子级的“印记”，然后转移到不同的液晶上。目标是设计一种新的分类方法，通过测量液晶相的兼容性来适应在其他液晶相中看到的分子有序性的扭曲。这个项目的影响超出了物理界。生物系统中存在排列整齐的聚合物网络，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造具有可定制特性的轻质材料。在社会影响方面，一个目标是通过关于液晶的外联活动让年轻学生和普通公众参与进来，液晶的视觉吸引力使他们能够有效地阐明科学概念。该项目还旨在为几篇本科生论文提供基础，包括与巴尔的摩地区大学合作的系桥项目招收的未被充分代表的少数族裔学生的论文。技术描述：这项研究项目使用液晶中的聚合物网络模板来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。一旦交联化，聚合物就携带了排列的记忆。如果液晶从聚合物网络中移除，可以在同一网络中重新填充另一种材料，这些材料必须符合聚合物施加的变形。该项目有不同的目标，其中包括(A)创建具有特定扭曲的模板化聚合物网络，(B)分析重新填充不同种类液晶的相同网络，以及(C)对扭曲之间的兼容性进行定量测量，并确定相之间的“距离”，从而提供了一种新的液晶相分类方法。其他项目目标包括将排列好的聚合物网络用于4D打印，或者作为生物或能源存储应用的轻质材料。利用光学显微镜、结合电子显微镜和小角X射线散射对液晶进行表征。材料研究部(DMR)的这项拨款支持研究液晶中的相结构和有序性，资金来自数学和物理科学(MPS)总监DMR中的凝聚态物理(CMP)计划。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。