Anisotropic self-assembly structures from isotropic building blocks

来自各向同性构件的各向异性自组装结构

• 批准号: 324078907
• 负责人: Professor Dr. Nicolas Vogel
• 金额: --
• 依托单位: Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/324078907?language=en
• 关键词: Anisotropic; self; assembly; structures; isotropic

Spherical particles form structures with hexagonal packing at all scales. The densest possible packing of spheres in three dimensions is formed by stacking hexagonally close packed arrangements of spheres in three dimensions. This intuitive structure translates all scales and is observed from the crystal structure of many atomic crystals to the macroscopic ordering of spherical objects. Self-assembly of spherical building blocks in two dimensions, for example at the surface of a water body, similarly results in hexagonally close-packed structures. In the first funding period, we have demonstrated that spherical colloidal particles can self-assemble into highly unexpected structures, for example anisotropic chains or phases with square symmetry. We have elaborated that these structures form at the air/water interface in the presence of amphiphilic additives, provided the following criteria are fulfilled. First, the amphiphiles need to adsorb to the interface irreversibly; second, they must not phase separate but mix with the colloidal particles; and third, they must be compressible. The essential finding of the first funding period was that these criteria lead to the formation of a two-dimensional, compressible shell around the particles at the interface. Upon compression on a Langmuir trough, these shells induce a repulsive component to the interaction potential of the particles. This repulsive component, in turn, causes the formation of the unconventional phases as minimum energy structures. Such phases were theoretically predicted by Jagla using particles interacting via a square-shoulder repulsion potential two decades ago and were for the first time experimentally realized in this project. Depending on the shape of the potential, theoreticians have predicted a wide range of complex phases, including different quasicrystalline structures. The approach developed in the first funding period provides a general strategy to achieve the required interaction potentials. However, the two-component mixtures prevented an accurate engineering of the interaction potential, required to experimentally access the entire range of complex assemblies predicted theoretically. In the second funding period, we will use the established knowledge to design one-component core-shell particles with controllable interfacial interaction potentials to experimentally realize the broad range of assembly structures predicted from Jagla-type interactions. The advantage of a one-component system is the potential to accurately engineer the interaction potential via the size and compressibility of the shell. With these tailored particle systems, we will deepen our understanding of the interfacial properties of particles in general, demonstrate that we can engineer their interaction potential, and use this possibility to generate self-assembled structures with unprecedented structural versatility, for example for surface nanostructuration using colloidal lithography.

球形粒子在所有尺度上形成六边形堆积结构。在三维空间中，最密集的球体排列是由球体的六边形紧密排列堆叠而成的。这种直观的结构可以转换所有尺度，从许多原子晶体的晶体结构到球形物体的宏观有序都可以观察到。球形构件在二维空间的自组装，例如在水体表面，同样会产生六边形的紧密排列结构。在第一个资助期，我们已经证明球形胶体粒子可以自组装成高度意想不到的结构，例如各向异性链或具有方形对称性的相。我们已经详细阐述了在两亲性添加剂存在的情况下，这些结构在空气/水界面形成，前提是满足以下标准。首先，两亲体需要不可逆地吸附到界面上；其次，它们不能相分离，而是与胶体颗粒混合；第三，它们必须是可压缩的。第一个资助期的重要发现是，这些标准导致在界面处粒子周围形成二维可压缩壳。当压缩在朗缪尔槽上时，这些壳层诱导出粒子相互作用势的排斥分量。这种排斥成分反过来又导致非常规相的形成，作为最小能量结构。20年前，Jagla利用粒子通过方肩斥力相互作用，从理论上预测了这种相，并在这个项目中首次通过实验实现。根据势的形状，理论家们预测了大范围的复杂相，包括不同的准晶体结构。在第一个供资期间制订的办法提供了实现所需相互作用潜力的一般战略。然而，双组分混合物阻碍了相互作用势的精确工程，这需要通过实验获得理论预测的整个复杂组合范围。在第二个资助期，我们将利用已建立的知识来设计具有可控界面相互作用势的单组分核壳粒子，以实验方式实现由jagla型相互作用预测的广泛组装结构。单组分系统的优点是可以通过壳体的大小和可压缩性精确地设计相互作用势。有了这些定制的粒子系统，我们将加深对粒子界面特性的理解，证明我们可以设计它们的相互作用潜力，并利用这种可能性产生具有前所未有的结构多功能性的自组装结构，例如使用胶体光刻技术进行表面纳米结构。