The assembly of (nano)particles into compact hierarchical structures yields emergent properties not found in the individual constituents. The formation of these structures relies on a profound knowledge of the nanoscale interactions between (nano)particles, which are often designed by researchers aided by computational studies. These interactions have an effect when the (nano)particles are brought into close proximity, yet relying only on diffusion to reach these closer distances may be inefficient. Recently, physical confinement has emerged as an efficient methodology to increase the volume fraction of (nano)particles, rapidly accelerating the time scale of assembly. Specifically, the high surface area of droplets of one immiscible fluid into another facilitates the controlled removal of the dispersed phase, resulting in spherical, often ordered, (nano)particle assemblies. In this review, we discuss the design strategies, computational approaches, and assembly methods for (nano)particles in confined spaces and the emergent properties therein, such as trigger-directed assembly, lasing behavior, and structural photonic color. Finally, we provide a brief outlook on the current challenges, both experimental and computational, and farther afield application possibilities.

中文翻译：

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密闭空间中（纳米）粒子三维组合的涌现特性

将（纳米）颗粒组装成紧凑的分层结构会产生单个成分所没有的新特性。这些结构的形成依赖于对（纳米）颗粒之间纳米级相互作用的深刻了解，这些知识通常是由研究人员在计算研究的帮助下设计的。当（纳米）粒子非常接近时，这些相互作用会产生影响，但仅依靠扩散来到达这些较近的距离可能效率低下。最近，物理限制已成为一种有效的方法来增加（纳米）粒子的体积分数，从而迅速加快组装的时间尺度。具体而言，一种不混溶流体的液滴与另一种流体的液滴的高表面积有利于分散相的受控去除，从而产生球形、通常有序的（纳米）颗粒组件。在这篇综述中，我们讨论了有限空间中（纳米）粒子的设计策略、计算方法和组装方法以及其中的新兴特性，例如触发定向组装、激光行为和结构光子颜色。最后，我们对当前的实验和计算挑战以及更远的应用可能性进行了简要展望。