The self-assembly of nanoparticles at interfaces

受配体保护的金属纳米颗粒被认为是新兴纳米技术中很有前途的一类材料，现在可以合成具有无数大小和形状可调的光学、电子和磁性能。表面上的金属纳米颗粒阵列因其在从纳米光子学到生物分子传感装置等各种应用中的潜力而受到广泛的研究。实现这些应用程序的一个主要障碍是用于制作具有不同复杂性和可调空间参数的阵列的可访问方法很少。目前，纳米颗粒阵列的制备面临两大挑战。首先，它们不形成具有长程有序的格；其次，对纳米颗粒间距的控制仅限于保护配体外壳涂层的厚度。本研究将通过研究纳米颗粒单层在水和疏水介质界面上的组装来解决这些挑战。我们将系统地探讨纳米粒子核心尺寸、配体尺寸和温度对单组分和多组分阵列自组装的影响。此外，将通过改变配体外壳和/或疏水介质（即空气与油）的疏水性来探索纳米颗粒与水和疏水介质之间的界面力平衡。同时测量薄膜的集体光学特性将用于跟踪薄膜的组装过程。在将这些薄膜转移到固体衬底上后，电子显微镜和原子力显微镜将用于可视化薄膜内单个纳米颗粒的排列。阐明控制纳米粒子自组装的规则有几个令人兴奋的结果。装配纳米粒子阵列的能力与独立控制纳米粒子的大小、形状和间距，目前是前所未有的。在这样做的过程中，人们将根据应用程序的要求访问他们的个人或集体材料属性。

Ligand-protected metal nanoparticles, which have been identified as a promising class of materials for emerging nanotechnologies, can now be synthesized with a myriad of size- and shape-tunable optical, electronic, and magnetic properties. Metal nanoparticle arrays on surfaces are under intense investigation for their potential in a variety of applications, ranging from nanophotonics to biomolecular sensing devices. A major hindrance to the realisation of these applications is the small number of accessible methods for making arrays with varying complexity and tunable spatial parameters.   Currently, the preparation of nanoparticle arrays faces two major challenges. First, they do not form lattices with long-range order; and secondly, control over nanoparticle spacing is limited to the thickness of the protective ligand shell coating. This research will address these challenges by studying the assembly of nanoparticle monolayers at the interface of water and a hydrophobic medium.  Nanoparticle core size, ligand size and temperature will be systematically explored for their influence on the self-assembly of single and multi-component arrays. Furthermore, the balance of interfacial forces between the nanoparticles and the water and hydrophobic media will be explored by changing the hydrophobicity of the ligand shell and/or the hydrophobic medium (i.e. air vs. oil). Simultaneous measurements of the film's collective optical properties will be used to track the film assembly process.  After transferring these films to solid substrates, electron microscopy and atomic force microscopy will be used to visualise the arrangement of individual nanoparticles within the films.   Elucidating the rules which govern nanoparticle self-assembly has several exciting consequences. The capability to assemble nanoparticle arrays with independent control over the nanoparticle size, shape, and spacing, is currently unprecedented. In doing so, one will gain access to either their individual or collective materials properties, as required by the application.