Polymer networks to induce deformations and topological defects in liquid crystals

非技术性描述：液晶不仅因为其在1000亿美元显示器行业的基础中所起的作用而令人感兴趣。它们是创造可通过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程度的有序性。不同类型的液晶在分子结构和排列方面具有显著的可变性，这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开辟了新的道路，而且还为更广泛的基于液晶的纳米材料开辟了新的道路;此外，它有助于回答有关不同物质状态之间转变的基本问题。本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相似性和差异性。聚合物可以分散在液晶中以产生分子顺序的“印记”，然后可以将其转移到不同的液晶中。我们的目标是设计一种新的分类方法，通过测量液晶相的相容性，以适应在其他液晶相看到的分子有序的扭曲。这个项目的影响超出了物理学界。聚合物的对齐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，该项目更广泛的目标涉及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联活动，让青年学生和公众参与进来，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，包括与巴尔的摩地区学院合作参加系桥课程的代表性不足的少数民族学生的论文。技术描述：该研究项目使用液晶中的聚合物网络模板对其他液晶相施加变形。模板聚合物网络可以通过将单体以低浓度分散在液晶中来获得。一旦交联，聚合物就携带对准的记忆。如果从聚合物网络中移除液晶，则相同的网络可以用另一种材料重新填充，这将必须符合聚合物施加的变形。该项目有各种目标，其中包括（a）创建具有特定扭曲的模板聚合物网络，（B）分析用不同种类的液晶重新填充的相同网络，以及（c）定量测量扭曲之间的相容性并识别相之间的“距离”，从而提供液晶相的新分类方法。其他项目目标包括将对齐的聚合物网络用于4D打印或作为生物学或储能应用的轻质材料。 用光学显微镜进行液晶的表征，结合电子显微镜和小角X射线散射。材料研究部（DMR）的这项资助支持研究相结构和液晶有序性，并由数学和物理科学（MPS）DMR中的凝聚态物理（CMP）计划提供资金。该奖项反映了NSF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 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.