Self-Organized Colloidal Assemblies in Confined Spaces:Formation Mechanism, Internal Structure and Resulting Optical Properties

密闭空间中的自组织胶体组件：形成机制、内部结构和由此产生的光学性质

• 批准号: 338276051
• 负责人: Professor Dr. Michael Engel
• 金额: --
• 依托单位: Lehrstuhl für Multiscale Simulation of Particulate Systems (MSS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/338276051?language=en
• 关键词: Self; Organized; Colloidal; Assemblies; Confined

The spontaneous organization of individual building blocks into ordered structures is extensively used in nature and found at all length scales, from crystallization processes, via composite materials, to living cells constituting complex tissue. Understanding the relationship between building blocks, environmental conditions, and resulting structure is of fundamental importance for controlling materials properties. Here we propose a joint experimental-theoretical investigation of the self-organization of spherical polymer colloidal particles in confined spaces. Such particles can easily be synthesized with high precision and serve as simple, nanoscale building blocks to study structure-property relationships in self-assembly processes. If sufficiently uniform in size, these particles self-assemble in a close-packed face-centered cubic lattice. These so-called colloidal crystals exhibit intense structural colors.Confining elements imposed upon the self-organizing particles can significantly alter the assembly process and may lead to entirely different colloidal crystals. Especially interesting confinements are emulsion droplets that prevent the formation of periodic structures by introducing boundaries and curvature. In preliminary experiments, we observed spherical assemblies with astonishing structural precision and geometry that enable us to investigate the effect of confinement on the resulting structure in unprecedented details. To date, the only model available to describe the assembly in spherical confinement relies on entropy maximization of non-interacting spheres with hard boundaries. While our observed structures follow the general trends predicted by this model, details of the formed structures indicate a richer phase behavior than expected. We anticipate that the kinetics of the assembly as well as the softness and deformability of the interface play a crucial role in the assembly process as well. Within this proposal we aim to establish a coherent model for the mechanism of confined self-assembly, to gain predictive power over the great many structural details arising from the self-organization of colloidal particles under external confinements and to reliably produce such particles in a uniform fashion using droplet-based microfluidics. Towards this aim, we will combine experimental, theoretical, and computational efforts to correlate experimentally observed assembly structures with particle simulations and free energy-minimization computations based on density and entropy as well as surface tension, deformability of the interface and its interaction with the colloidal particles. Finally, we will investigate the resulting optical properties of the assembled superstructures as an example of a functional property that can be tailored via the internal structure of the self-organized spherical colloidal assemblies.

个体构建块自发组织成有序结构在自然界中广泛使用，并且在所有长度尺度上都有发现，从结晶过程，通过复合材料，到构成复杂组织的活细胞。了解构建块、环境条件和最终结构之间的关系对于控制材料性能至关重要。在这里，我们提出了一个联合的实验和理论研究的球形聚合物胶体粒子在有限空间中的自组织。这种颗粒可以很容易地以高精度合成，并作为简单的纳米级构建块来研究自组装过程中的结构-性能关系。如果尺寸足够均匀，这些粒子会自组装成紧密堆积的面心立方晶格。这些所谓的胶体晶体呈现出强烈的结构色彩。施加在自组织颗粒上的限制元素可以显著改变组装过程，并可能导致完全不同的胶体晶体。特别有趣的限制是乳液液滴，通过引入边界和曲率来防止周期性结构的形成。在初步实验中，我们观察到了具有惊人结构精度和几何形状的球形组件，使我们能够以前所未有的细节研究限制对所产生结构的影响。到目前为止，唯一的模型可用于描述组装在球形约束依赖于熵最大化的非相互作用的领域与硬边界。虽然我们观察到的结构遵循该模型预测的一般趋势，但形成的结构的细节表明比预期更丰富的相行为。我们预期组装的动力学以及界面的柔软性和可变形性在组装过程中也起着至关重要的作用。 在这个建议中，我们的目标是建立一个连贯的模型的机制，限制自组装，获得预测能力的大量结构细节所产生的胶体粒子的自组织下外部约束，并可靠地产生这样的粒子在一个统一的方式使用液滴为基础的微流体。为此，我们将结合联合收割机的实验，理论和计算的努力，相关的实验观察到的组装结构与粒子模拟和自由能最小化计算的基础上密度和熵以及表面张力，变形的接口和它的相互作用的胶体颗粒。最后，我们将研究组装的超结构的光学性质，作为可以通过自组织球形胶体组装体的内部结构来定制的功能性质的一个例子。