Institut für Theoretische Physik, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Wien, Austria.
CNR-ISC, Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy.
Int J Mol Sci. 2020 Nov 16;21(22):8621. doi: 10.3390/ijms21228621.
Non-spherical colloids provided with well-defined bonding sites-often referred to as patches-are increasingly attracting the attention of materials scientists due to their ability to spontaneously assemble into tunable surface structures. The emergence of two-dimensional patterns with well-defined architectures is often controlled by the properties of the self-assembling building blocks, which can be either colloidal particles at the nano- and micro-scale or even molecules and macromolecules. In particular, the interplay between the particle shape and the patch topology gives rise to a plethora of tilings, from close-packed to porous monolayers with pores of tunable shapes and sizes. The control over the resulting surface structures is provided by the directionality of the bonding mechanism, which mostly relies on the selective nature of the patches. In the present contribution, we investigate the effect of the patch size on the assembly of a class of anisotropic patchy colloids-namely, rhombic platelets with four identical patches placed in different arrangements along the particle edges. Larger patches are expected to enhance the bond flexibility, while simultaneously reducing the bond selectivity as the single bond per patch condition-which would guarantee a straightforward mapping between local bonding arrangements and long-range pattern formation-is not always enforced. We find that the non-trivial interplay between the patch size and the patch position can either promote a parallel particle arrangement with respect to a non-parallel bonding scenario or give rise to a variety a bonded patterns, which destroy the order of the tilings. We rationalize the occurrence of these two different regimes in terms of single versus multiple bonds between pairs of particles and/or patches.
具有明确定义的结合位点的非球形胶体——通常被称为补丁——由于其能够自发组装成可调表面结构，因此越来越受到材料科学家的关注。具有明确定义结构的二维图案的出现通常由自组装构建块的性质控制，这些构建块可以是纳米和微米级的胶体颗粒，甚至是分子和大分子。特别是，颗粒形状和补丁拓扑之间的相互作用产生了大量的平铺图案，从紧密堆积到具有可调形状和大小的多孔单层。对所得表面结构的控制是由结合机制的方向性提供的，该方向性主要依赖于补丁的选择性。在本研究中，我们研究了补丁尺寸对一类各向异性补丁胶体组装的影响，即具有四个相同补丁的菱形血小板，它们沿着颗粒边缘以不同的方式排列。较大的补丁有望增强键的灵活性，同时降低键的选择性，因为每个补丁的单键条件——这将保证局部键合排列和远程图案形成之间的直接映射——并不总是得到保证。我们发现，补丁尺寸和补丁位置之间的复杂相互作用既可以促进相对于非平行键合情况的平行颗粒排列，也可以产生各种键合图案，从而破坏平铺的有序性。我们根据粒子对之间的单键和/或双键来解释这两种不同情况的发生。
