Magneto-optically switchable anisotropic suspensions and gels

在这个项目中，我们联合收割机结合软物质物理学的两个成功的概念，磁流体和液晶。目标是开发一类对磁场敏感的新型多功能材料，并可用于磁光开关和磁机械效应。我们将联合收割机铁磁流体和功能化的磁性纳米颗粒与溶致液晶悬浮液和热致液晶相结合。铁磁性纳米颗粒提供对磁场的敏感性。不等轴微晶或液晶介晶有助于双折射光学性质。这种组合打开了多种应用的潜力。稳定的悬浮液的制备和表征在本专题计划的前期应用中，此外，我们还成功地尝试制备各向异性铁凝胶。该项目计划开展的活动的目的是研究磁性纳米颗粒与不同系统中的局部复杂各向异性基质的相互作用。重点放在基体结构对复合材料的磁光和粘弹性性能的影响上：外部磁场引起磁性纳米颗粒的自组织，从而重新组织各向异性环境（基体）。矩阵的反馈决定了磁性亚相的结构形成动力学以及光学和机械性能。我们将研究三种不同的基质系统，分散在各向同性液体介质中的板状和棒状颜料颗粒（颜料微晶），具有线状内部结构的有机凝胶和有机液晶。一个特殊的方面是从各向同性到各向异性矩阵的过渡。最相关的实验表征技术是磁光开关，磁致双折射和二向色性的测量，以及磁致机械扭矩。这些技术伴随着流变学研究，磁弛豫测量法（MRX）和磁弛豫测量法（ACS），以及与专题计划中其他小组合作的其他方法。

In this project we combine two successful concepts of Soft Matter physics, magnetic fluids and liquid crystals. The goal is the development of a new class of multifunctional materials that are sensitive to magnetic fields and can be used for magneto-optical switching and magneto-mechanical effects. We combine ferrofluids and functionalized magnetic nanoparticles with lyotropic nematic suspensions and thermotropic liquid crystals. Ferromagnetic nanoparticles provide the sensitivity against magnetic fields. Anisometric crystallites or liquid-crystalline mesogens contribute birefringent optical properties. This combination opens the potential for multiple applications. Stabile suspensions were prepared and characterized in the previous application periods of this topical program, in addition we made successful attempts to prepare anisotropic ferrogels. The aim of the planned activities in this project is the investigation of the interactions of magnetic nanoparticles with the localen complex anisotropic matrix in different systems. The focus is laid on the influence of the matrix structure on the magneto-optical and viscoelastic properties of the composites: External magnetic fields cause a self-organization of the magnetic nanoparticles, which in turn reorganize the anisotropci environment (the matrix). The feedback of the matrix determines the structure forming dynamics of the magnetic subphase as well as the optical and mechanical properties. We will investigate three different matrix systems, plate-like and rod-like nonmagnetic particles (pigment crystallites) dispersed in an isotrop liquid medium, organo-gels with thread-like internal structure and organic liquid crystals. A special aspect is the transition from isotropic to anisotropic matrices. The most relevant experimental characterization techniques are magneto-optical switching, measurements of magnetically induced birefringence and dichroism, as well as magnetically induced mechanical torques. These techniques are accompanied by rheological studies, magnetorelaxometry (MRX) and susceptometry (ACS), and other methods in cooperation with other groups within the topical program.