Structure and dynamics of nematic phases with strong smectic fluctuations formed by bent-core mesogens

具有非圆柱形介相的介相具有显著的复杂结构，并且在某些相中具有非常快的电光响应。例如，由弯曲介质的空间相互作用驱动的极性和近晶波动增强，导致形成对外部场具有强敏感性的簇相。这种高响应材料具有广阔的应用前景。介原的形状也可以通过外部刺激如光异构分子中的光来控制。这个提议是基于我们在马格德堡的小组和哈雷马丁·路德大学有机化学系（C. Tschierske和M. Alaasar）之间的广泛合作。该提案的主要目的是研究光可调谐纳米结构对液晶的微观和宏观性质的影响。我们建议研究复杂的液晶体系，如形成向列相的光开关介元，扭曲-弯曲向列相，具有螺旋纳米结构的弯核近晶相，以及新发现的极性向列相。核心问题是中间相的纳米结构和光刺激如何影响液晶的体积和表面特性，以及它如何影响基于这些材料的胶体的行为。我们将研究液晶在块状、液滴和细丝中的行为。拟议的研究将分五个阶段进行，首先是体特性的表征，然后将重点转移到纯光可切换化合物和仅具有光可切换表面的系统中的光驱动锚定转换的研究。我们将运用所学的知识来理解LC矩阵中固体夹杂物的行为。将研究胶体粒子在向列相、扭弯向列相和铁电向列相中的平移和旋转运动。在最后阶段，我们将探索具有光异构介原的液晶细丝的动力学。本研究的结果将阐明光驱动介晶形态变化、结构形成和新型液晶系统性能之间相互作用的机制。

Mesophases with mesogens of non-cylindrical shapes exhibit remarkable complex structures and, in some phases, a very fast electro-optical response.Enhanced polar and smectic fluctuations, driven by steric interactions of bent mesogens, for instance, result in the formation of cluster phases with strong susceptibility to external fields. Such highly responsive materials have broad perspectives for applications. The shape of the mesogens can also be controlled by external stimuli such as light in photoisomerisable molecules. This proposal is based on the extensive collaboration between our group in Magdeburg and the Department of Organic Chemistry at Martin Luther University Halle (C. Tschierske and M. Alaasar). The proposal's primary aim is to investigate the effects of the photo-tuneable nanostructures on liquid crystals' micro and macroscopical properties in bulk and restricted geometry. We propose to study complex liquid crystalline systems such as photoswitchable mesogens forming nematic, twist-bend nematic phase, bent-core smectic phases with the heliconical nanostructure, and the newly discovered polar nematic phase.The central questions are how the nanostructure of the mesophase and photo-stimulation affect the bulk and surface properties of liquid crystals, how it affects the behaviour of colloids based on such materials. We will study the behaviour of liquid crystals in bulk, in droplets and filaments as well. The proposed research will be conducted in five stages, starting with the characterisation of the bulk properties and shifting the focus to the studies of light-driven anchoring transitions in pure photoswitchable compounds and systems with photoswitchable surfaces only. We will employ the acquired knowledge for understanding the behaviour of the solid inclusions in an LC matrix. The translational and rotational motions of colloidal particles will be investigated in the nematic, twist-bend nematic and ferroelectric nematic phases. At the final stage, we will explore the dynamics of liquid crystal filaments with photoismerisable mesogens. The output of this research will elucidate the mechanisms underlying the interplay between the light-driven mesogenic shape changes, structure formation and the properties of the novel liquid crystalline systems.