Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions
Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions
复制标题
DOI：
10.1021/acs.nanolett.0c01311
复制
发表时间：
2020-05-13
期刊：
影响因子：
10.8
通讯作者：
Milliron, Delia J.
中科院分区：
文献类型：
--
作者：
Cabezas, Camila A. Saez;Sherman, Zachary M.;Milliron, Delia J.
纳米晶体凝胶提供了一个强大的框架，可以将纳米级性质转化为块状材料，并通过组装的微观结构来设计紧急性质。然而，许多已建立的凝胶化策略依赖于化学反应和特定的相互作用，例如，稳定纳米晶体表面的配体或离子，因此不容易转移。在这里，我们报告了一种通过非特异性和纯熵耗尽吸引应用于三种类型的金属氧化物纳米晶体的一般凝胶化策略。两种组成不同的球形纳米晶体的凝胶阈值在定量上一致，证明了该方法对不同化学物质的适应性。与理论相行为预测一致，纳米晶体立方体比纳米晶体球体在更低的聚合物浓度下形成凝胶，允许形状作为控制凝胶的手柄。这些结果表明，耗竭驱动组装的基本基础，传统上与较大的胶体颗粒有关，也适用于纳米尺度。
Nanocrystal gelation provides a powerful framework to translate nanoscale properties into bulk materials and to engineer emergent properties through the assembled microstructure. However, many established gelation strategies rely on chemical reactions and specific interactions, e.g., stabilizing ligands or ions on the nanocrystals' surfaces, and are therefore not easily transferable. Here, we report a general gelation strategy via nonspecific and purely entropic depletion attractions applied to three types of metal oxide nanocrystals. The gelation thresholds of two compositionally distinct spherical nanocrystals agree quantitatively, demonstrating the adaptability of the approach for different chemistries. Consistent with theoretical phase behavior predictions, nanocrystal cubes form gels at a lower polymer concentration than nanocrystal spheres, allowing shape to serve as a handle to control gelation. These results suggest that the fundamental underpinnings of depletion-driven assembly, traditionally associated with larger colloidal particles, are also applicable at the nanoscale.