Ligand Interactions and Nanoparticle Shapes Guide the Pathways toward Interfacial Self-Assembly
Ligand Interactions and Nanoparticle Shapes Guide the Pathways toward Interfacial Self-Assembly
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DOI：
10.1021/acs.langmuir.1c02804
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发表时间：
2022-01-27
期刊：
影响因子：
3.9
通讯作者：
Escobedo, F. A.
中科院分区：
文献类型：
--
作者：
Gupta, U.;Escobedo, F. A.
非平衡态分子动力学模拟被用来探测流体-流体界面处的多面体形纳米颗粒（NP）的高度有序的外延连接超晶格形成背后的驱动力。通过明确建模粗粒度的配体，盖NP表面，它表明，NP的形状和时间依赖性的小面特定的配体密度的差异引起了截然不同的转换机制。我们的研究结果表明，周围的溶剂化环境的屏蔽粒子间的相互作用的程度有显着的影响可逆性，并最终获得的最终二维超晶格的相干性。对于所研究的粒子形状，六方预组装和正方形超晶格最终组装（在优先配体从{100}面解吸时）是普遍的;然而，立方八面体NP形成中间外延键合的分支簇，其最终生长并重排成正方形晶格;与此相反，截短的八面体NP表现出由其众多的{111}-有利于线性NP棒堆叠的配体。为了跟踪系统中的初始顺序，我们还概述了一组新的顺序参数，用于测量最近邻对之间的局部方向对齐。在这项工作中先进的模拟协议可以铺平道路，探索与纳米粒子的界面自组装相关的巨大的相空间。
Non-equilibrium molecular dynamics simulations are used to probe the driving forces behind the formation of highly ordered, epitaxially connected superlattices of polyhedral-shaped nanoparticles (NPs) at fluid-fluid interfaces. By explicitly modeling coarse-grained ligands that cap the NP surface, it is shown that differences in NP shapes and time-dependent facet-specific ligand densities give rise to drastically different transformation mechanisms. Our results indicate that the extent of screening of the inter-particle interactions by the surrounding solvation environment has a significant impact on reversibility and ultimately the coherence of the final two-dimensional superlattice obtained. For the particle shapes examined, a hexagonal pre-assembly and a square superlattice final assembly (upon preferential ligand desorption from {100} facets) were prevalent; however, cuboctahedral NPs formed intermediate epitaxially bonded branched clusters, which eventually grew and rearranged into a square lattice; in contrast, truncated octahedral NPs exhibited an abrupt rhombic-to-square transition driven by the clustering of their numerous {111}-ligands that favored the stacking of linear NP rods. To track the incipient order in the system, we also outline a set of novel order parameters that measure the local orientation alignment between nearest-neighbor pairs. The simulation protocols advanced in this work could pave the way forward for exploration of the vast phase space associated with the interfacial self-assembly of NPs.