Nearest-neighbour nanocrystal bonding dictates framework stability or collapse in colloidal nanocrystal frameworks

by Williams, TE; Ushizima, D; Zhu, C; Anders, A; Milliron, DJ; Helms, BA

Chemical Communications (Cambridge, England); Apr 27 2017; doi: 10.1039/c6cc10183f

Block copolymers serve as architecture-directing agents for the assembly of colloidal nanocrystals into a variety of mesoporous solids. Here we report the fundamental order-disorder transition in such assemblies, which yield, on one hand, ordered colloidal nanocrystals frameworks or, alternatively, disordered mesoporous nanocrystal films. Our determination of the order-disorder transition is based on extensive image analysis of films after thermal processing. The number of nearest-nanocrystal neighbours emerges as a critical parameter dictating assembly outcomes, which is in turn determined by the nanocrystal volume fraction (fNC). We also identify the minimum fNC needed to support the structure against collapse.

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