Ionic Liquid Crystals Confined in Nanoporous Solids: Self-Assembly, Molecular Mobility and Electro-Optical Functionalities

离子液晶(ILC)架起了传统液晶和离子物质之间的桥梁。已经发现盘状柱状相以及柱状相中非常高的一维离子迁移率，并从势能的角度对其进行了研究。这些功能在很大程度上取决于方向类型和翻译顺序。原则上，可以通过在纳米结构固体模板中嵌入ILC来优化这些顺序。然而，关于纳米限制对ILC的影响的知识非常稀少，尽管它提供了全新的自组装路径，从而提供了电光功能。在这里，我们建议探索离子液晶在纳米多孔固体中的相行为，并将其与相应的体相唯象联系起来。应仔细检查作为孔大小和孔表面化学函数的行为如何变化，特别是关于亲水和疏水孔壁。为此，应对单块纳米多孔二氧化硅、硅和氧化铝薄膜中的ILCs进行基于同步加速器的X射线衍射、介电光谱和量热分析。这将使我们能够详细了解受限介元的结构和动力学。该项目尤其得益于所涉研究小组的互补专业知识，即微观平移和定向有序(HUBER)、热力学和分子动力学(舍恩哈尔斯)和ILCs的量身定制合成(Laschat)。此外，还将系统地探索光学各向异性、旋光性、介电性质和电导率方面的功能，并针对中间相形成和介元-孔壁相互作用量身定制介元相互作用，以优化这些功能。具体地说，我们打算探索沿着柱状轴形成具有高载流子迁移率的盘状六方相的ILC。此外，将研究手性ILCs与孔的相互作用，关于限制诱导的手性中间相的形成，体态中没有手性中间相。预计通过适当的孔表面接枝和孔径选择，可以调谐光学和电学功能。这项研究的目的是对受限ILC的物理化学有一个基本的了解，同时也是为了了解所产生的杂化材料的功能，这些杂化材料包括在整体固体中提供机械稳定性的软功能ILC填充物。该项目的成功实现需要三个研究小组的密切合作，因为化学分子结构(合成)决定了纳米多孔固体中的超分子结构和分子动力学以及与约束壁的相互作用。除了预期的科学成果的协同效益外，博士生还将从他们的科学教育和本研究项目的合作精神中受益匪浅。

Ionic liquid crystals (ILC) bridge the gap between conventional liquid crystalline and ionic matter. Discotic columnar phases along with very high 1-D ion mobility in columnar phases have been found and studied with regard to potential functionalities. These functionalities depend strongly on the type of orientation and translation order. In principle, these orders can be optimized by embedding ILCs in nanostructured solid templates. However, very sparse knowledge is available about the effect of nanoconfinement on ILCs, even though it provides entirely novel self-assembly paths and thus electro-optical functionalities. Here we propose the exploration of the phase behavior of ionic liquid crystals in nanoporous solids and to relate it to the corresponding bulk phenomenology. It shall be scrutinized how the behavior changes as a function of pore-size and pore-surface chemistry, in particular with regard to hydrophilic and hydrophobic pore walls. To this end synchrotron-based X-ray diffraction, dielectric spectroscopy, calorimetry on ILCs confined in monolithic nanoporous silica, silicon and alumina membranes shall be performed. This will allow detailed insights in the structure and dynamics of the confined mesogens. The project particularly profits from the complementary expertise of the research groups involved, i.e. microscopic translational and orientational order (Huber), thermodynamics and molecular dynamics (Schoenhals) and tailored synthesis of ILCs (Laschat). Moreover, the functionalities with regard to optical anisotropy, optical activity, dielectric properties and electrical conductivity will be systematically explored and the mesogen interactions tailored with respect to mesophase formation and mesogen-pore wall interaction in order to optimize these functionalities. Specifically, we intend to explore ILCs forming discotic hexagonal phases with high charge carrier mobilities along the columnar axis. In addition, interactions of chiral ILCs with the pores will be studied regarding confinement-induced formation of chiral mesophases, absent in the bulk state. It is expected that by proper pore surface-grafting and pore-size selection optical and electrical functionalities can be tuned. The study is aimed at a fundamental understanding of the physical chemistry of confined ILCs, but also at the functionalities of the resulting hybrid materials, consisting of soft functional ILC fillings in monolithic solids providing mechanical stability.The successful realization of the project requires an intense cooperation between the three research groups because the chemical molecular structure (synthesis) determines the supermolecular structures and the molecular dynamics as well as the interaction with the confining walls in nanoporous solids. Besides the expected synergistic benefit on the scientific results the PhD students will significantly profit in their scientific education and from the cooperative spirit of this research project.