Dynamics and Interactions of Colloidal Particles on Freely Suspended Smectic Films

自由悬浮近晶薄膜上胶体颗粒的动力学和相互作用

• 批准号: 191437318
• 负责人: Professor Dr. Ralf Stannarius
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/191437318?language=en
• 关键词: Dynamics; Interactions; Colloidal; Particles; Freely

Freely suspended smectic films are unique liquid structures with thicknesses between a few molecular layers and a few microns, with lateral extensions up to several centimeters. They represent easily prepared models of two-dimensional (2D) fluids. In the transition from three to two dimensions, the description of the dynamics often simplifies, but there are also qualitatively new phenomena. Under certain circumstances, the dynamics in a two-dimensional liquid can be relatively complicated (see, e.g. the Stokes paradox).Depending on the mesophase, smectic films may be anisotropic (smectic C or smectic C*) or isotropic (smectic A) in the film plane. We study the motion of particles in the quasi-2D geometry of such films, and their interactions with the surrounding director field.In the previous funding period, the preparation of solid and liquid inclusions in smectic films was developed and the motion of solid beads was studied with the aid of polarized light microscopy experiments. We could test and verify the Saffman-Delbrück model for the mobility of inclusions in 2D fluids and the transition between the limiting cases of the model was observed. A technique to shoot microdroplets onto smectic films was developed, and the impact of these droplets, their incorporation into the films or the tunneling through the films were described. Coalescence prozesses of circular islands were observed and analyzed quantitatively. The findings for 2D isotropic SmA films have now been published. We will now focus on the motion in anisotropic SmC films, and investigate anisometric (shape anisotropic) particles. Two new and interesting aspects are the incorporation of the set of shear viscosities and the rotational viscosity in anisotropic 2D fluids, as well as the reorientation dynamics of rod-shaped inclusions.For both topics, there are qualitative preliminary studies, but neither the group of the applicant nor other research groups so far have obtained experimental results. We plan both quantitative experiments and numerical (FEM) simulations. They will form the basis of a systematic description of hydrodynamic processes in quasi-2D anisotropic fluids.

自由悬浮的近晶薄膜是独特的液体结构，其厚度在几个分子层和几微米之间，横向延伸高达几厘米。它们代表易于制备的二维（2D）流体模型。在从三维到二维的过渡中，动力学的描述往往简化，但也有定性的新现象。在某些情况下，二维液体中的动力学可能相对复杂（参见，例如斯托克斯悖论）。根据中间相，近晶薄膜在薄膜平面上可能是各向异性的（近晶C或近晶C*）或各向同性的（近晶A）。我们研究了这种薄膜的准二维几何结构中粒子的运动，以及它们与周围指向矢场的相互作用。在上一个资助期，我们开发了近晶薄膜中固体和液体包裹体的制备，并借助偏振光显微镜实验研究了固体珠的运动。我们可以检验和验证Saffman-Delbrück模型的二维流体中的包裹体的流动性和模型的极限情况之间的过渡观察。提出了一种将微滴喷射到近晶薄膜上的技术，并对微滴的撞击、微滴的掺入和微滴的隧穿进行了描述。观察并定量分析了圆形岛的聚并过程。2D各向同性SmA薄膜的研究结果现已发表。我们现在将专注于各向异性SmC薄膜中的运动，并研究不等轴（形状各向异性）颗粒。两个新的和令人感兴趣的方面是在各向异性的2D流体中的剪切粘度和旋转粘度的集合的合并，以及棒状夹杂物的再取向动力学。对于这两个主题，有定性的初步研究，但到目前为止，申请人的小组和其他研究小组都没有获得实验结果。我们计划定量实验和数值（FEM）模拟。它们将形成准二维各向异性流体中的流体动力学过程的系统描述的基础。

项目成果

Defect Interactions in Anisotropic Two-Dimensional Fluids.

各向异性二维流体中的缺陷相互作用

• DOI: 10.1103/physrevlett.117.157801
• 发表时间: 2016
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: R. Stannarius;K. Harth
• 通讯作者: K. Harth

Stripe instabilities in the menisci of free-standing smectic films: influence of the phase sequence of the mesogenic material

独立式近晶薄膜弯月面的条纹不稳定性：介晶材料相序的影响

• DOI: 10.1080/02678292.2018.1446558
• 发表时间: 2017
• 期刊: Liquid Crystals
• 影响因子: 2.2
• 作者: R. Stannarius;A. Eremin;K. Harth
• 通讯作者: K. Harth

Brownian dynamics of elongated particles in a quasi-two-dimensional isotropic liquid

准二维各向同性液体中细长粒子的布朗动力学

• DOI: 10.1103/physrevfluids.2.124202
• 发表时间: 2017
• 期刊: arXiv: Fluid Dynamics
• 作者: C. Klopp;R. Stannarius;A. Eremin
• 通讯作者: A. Eremin

Smectic C to smectic A transition induced mechanically by the rupture of freely suspended liquid crystal films.

由悬浮液晶膜破裂机械诱导的近晶 C 到近晶 A 的转变

• DOI: 10.1039/c7sm00219j
• 发表时间: 2017
• 期刊: Soft matter
• 影响因子: 3.4
• 作者: T. Trittel;K. Harth;R. Stannarius
• 通讯作者: R. Stannarius

Rupture and recoil of bent-core liquid crystal filaments.

弯芯液晶丝的断裂和反冲

• DOI: 10.1039/c6sm00290k
• 发表时间: 2016
• 期刊: Soft matter
• 影响因子: 3.4
• 作者: S. M. Salili;T. Ostapenko;O. Kress;C. Bailey;W. Weissflog;K. Harth;A. Eremin;R. Stannarius;A. Jakli
• 通讯作者: A. Jakli