Competition of shape and interaction patchiness for self-assembling nanoplates

• Published in: Nature chemistry Vol. 5; no. 6; pp. 466 - 473
• Main Authors: Ye, Xingchen, Chen, Jun, Engel, Michael, Millan, Jaime A., Li, Wenbin, Qi, Liang, Xing, Guozhong, Collins, Joshua E., Kagan, Cherie R., Li, Ju, Glotzer, Sharon C., Murray, Christopher B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2013; Nature Publishing Group
• Subjects: 639/638/563; 639/925/357/341; Analytical Chemistry; Biochemistry; Chemistry; Chemistry/Food Science; Engineering; Inorganic Chemistry; Ligands; Materials science; Monte Carlo simulation; Nanocrystals; Organic Chemistry; Physical Chemistry; Ann Arbor Michigan; United States > US; Massachusetts; Pennsylvania; Michigan
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.1651

Progress in nanocrystal synthesis and self-assembly enables the formation of highly ordered superlattices. Recent studies focused on spherical particles with tunable attraction and polyhedral particles with anisotropic shape, and excluded volume repulsion, but the effects of shape on particle interaction are only starting to be exploited. Here we present a joint experimental–computational multiscale investigation of a class of highly faceted planar lanthanide fluoride nanocrystals (nanoplates, nanoplatelets). The nanoplates self-assemble into long-range ordered tilings at the liquid–air interface formed by a hexane wetting layer. Using Monte Carlo simulation, we demonstrate that their assembly can be understood from maximization of packing density only in a first approximation. Explaining the full phase behaviour requires an understanding of nanoplate-edge interactions, which originate from the atomic structure, as confirmed by density functional theory calculations. Despite the apparent simplicity in particle geometry, the combination of shape-induced entropic and edge-specific energetic effects directs the formation and stabilization of unconventional long-range ordered assemblies not attainable otherwise. Thin lanthanide fluoride nanoplates are shown to self-organize at the liquid/air interface into long-range-ordered two-dimensional planar tilings. In this joint experimental–computational, multiscale investigation, the assembly behaviour is shown to be dictated by entropic forces arising from particle shape and enthalpic forces arising from interaction anisotropy.