Lyotropic Liquid Crystal Gels: Structure, Rheology, and Stimuli-Response

溶致液晶凝胶：结构、流变学和刺激响应

• 批准号: 289272413
• 负责人: Professor Dr. Frank Gießelmann
• 金额: --
• 依托单位: Institut für Physikalische Chemie (IPC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/289272413?language=en
• 关键词: Lyotropic; Liquid; Crystal; Gels; Structure

After we succeeded in the first part of the project to produce lyotropic liquid crystal (LLC) gels with lamellar as well as nematic and hexagonal order in a controlled and reproducible way, the follow-up project will mainly focus on the specific properties and possible applications of LLC gels as water-based stimuli-responsive materials. LLC gels are the lyotropic counterparts of thermotropic liquid crystal gels and elastomers (LCEs) which are today the workhorses in the rapidly emerging fields of soft robotics and biomimetic actuation. In comparison to their thermotropic counterparts, LLC gels are cheap to prepare and compatible to aqueous media - they are thus expected to respond to a completely different range of chemical and biological stimuli. We consider this an extremely promising perspective that is well worth being placed in the focus of our follow-up project. The ultimate goal of the follow-up project is thus to explore the potential of LLC gels as stimuli-responsive materials. However, to successfully pursue this overall objective, two basic requirements must first be met, namely:(1) the availability of (mainly) nematic LLC gels with tailored thermal, structural and rheo-logical properties and(2) the successful preparation of aligned LLC gels with well-defined macroscopically anisotropic director configurations.The central research questions which will thus be addressed in the follow-up project are as follows:(a) How can (nematic) LLC gels with tailored thermal, structural and rheological properties be rationally designed? How does the composition of the LLC parent system (surfactant, cosurfactant, water) and the gelator concentration affect the clearing temperature, the sol-gel temperature, the orientational order parameter and the rheological properties of the LLC gels?(b) How can (nematic) LLC gels be processed into aligned specimens with a well-defined macroscopically anisotropic director configuration? Possible options are magnetic field alignment, surface alignment in restricted geometries, or shear alignment.(c) How do aligned LLC gels swell in water, aqueous solutions or other water-miscible solvents such as alcohols? How does the solvent absorption affect the phase behaviour? To which extent is the associated change in shape anisotropic?(d) How do aligned LLC gels respond to changes in temperature and, in particular, to temperature induced phase transitions? To which extent is the associated change in shape anisotropic and reversible? How fast is the thermo-mechanical response?Together with the results from the preceeding projects, the answers to these questions will lead to a first coherent picture of the preparation, the structure and the application of LLC gels, which allows a meaningful completion of the overall project.

在我们以可控和可重复的方式制备具有层状、向列相和六方有序的溶致液晶(LLC)凝胶的第一部分成功后，后续的项目将主要关注LLC凝胶作为水基刺激响应材料的特性和可能的应用。LLC凝胶是热致液晶凝胶和弹性体(LCE)的溶致对应物，后者是当今迅速崛起的软机器人和仿生驱动领域的主力。与热致凝胶相比，LLC凝胶的制备成本低，并且与水介质兼容-因此，它们有望对完全不同范围的化学和生物刺激做出反应。我们认为这是一个非常有希望的前景，值得将其置于我们后续项目的重点。因此，后续项目的最终目标是探索LLC凝胶作为刺激反应材料的潜力。然而，为了成功地实现这一总体目标，首先必须满足两个基本要求，即：(1)(主要)具有定制的热、结构和流变性的向列型LLC凝胶的可用性；(2)成功地制备具有明确的宏观各向异性导向器构型的定向LLC凝胶。因此，将在后续项目中解决的中心研究问题如下：(A)如何合理地设计具有定制的热、结构和流变性的(向列型)LLC凝胶？LLC母体体系的组成(表面活性剂、助表面活性剂、水)和凝胶剂浓度如何影响LLC凝胶的澄清温度、溶胶-凝胶温度、取向有序参数和流变性？(B)如何将(向列型)LLC凝胶加工成具有明确宏观各向异性定向构型的排列样品？可能的选择是磁场排列、限制几何形状的表面排列或剪切排列。(C)排列的LLC凝胶在水、水溶液或其他可溶于水的溶剂(如醇)中如何膨胀？溶剂吸收如何影响相行为？形状的变化在多大程度上是各向异性的？(D)排列的LLC凝胶如何响应温度的变化，特别是温度引起的相变？相关的形状变化在多大程度上是各向异性和可逆的？热机械反应的速度有多快？与之前项目的结果一起，对这些问题的回答将导致对LLC凝胶的制备、结构和应用的第一个连贯的图景，这使得整个项目能够有意义地完成。