Brunner Julian, Maier Britta, Rosenberg Rose, Sturm Sebastian, Cölfen Helmut, Sturm Elena V
Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Institute for Solid State Research, Leibniz Institute for Solid State and Materials Research Dresden, Helmholzstraße 20, 01069, Dresden, Germany.
Chemistry. 2020 Nov 26;26(66):15242-15248. doi: 10.1002/chem.202002873. Epub 2020 Oct 16.
Applications in the fields of materials science and nanotechnology increasingly demand monodisperse nanoparticles in size and shape. Up to now, no general purification procedure exists to thoroughly narrow the size and shape distributions of nanoparticles. Here, we show by analytical ultracentrifugation (AUC) as an absolute and quantitative high-resolution method that multiple recrystallizations of nanocrystals to mesocrystals is a very efficient tool to generate nanocrystals with an excellent and so-far unsurpassed size-distribution (PDI =1.0001) and shape. Similar to the crystallization of molecular building blocks, nonclassical recrystallization removes "colloidal" impurities (i.e., nanoparticles, which are different in shape and size from the majority) by assembling them into a mesocrystal. In the case of nanocrystals, this assembly can be size- and shape-selective, since mesocrystals show both long-range packing ordering and preferable crystallographic orientation of nanocrystals. Besides the generation of highly monodisperse nanoparticles, these findings provide highly relevant insights into the crystallization of mesocrystals.
材料科学和纳米技术领域的应用对纳米颗粒的尺寸和形状的单分散性要求日益提高。到目前为止，还不存在能彻底缩小纳米颗粒尺寸和形状分布范围的通用纯化方法。在此，我们通过分析超速离心法（AUC）这一绝对定量的高分辨率方法表明，纳米晶体多次重结晶形成介晶是一种非常有效的工具，可生成尺寸分布极佳（多分散指数PDI = 1.0001）且形状良好且迄今为止无与伦比的纳米晶体。与分子构建块的结晶过程类似，非经典重结晶通过将“胶体”杂质（即形状和尺寸与大多数不同的纳米颗粒）组装成介晶来去除它们。对于纳米晶体而言，这种组装可以是尺寸和形状选择性的，因为介晶既显示出纳米晶体的长程堆积有序性，又显示出择优晶体取向。除了生成高度单分散的纳米颗粒外，这些发现还为介晶的结晶过程提供了极具相关性的见解。
