Time‐Resolved SAXS Study of Polarity‐ and Surfactant‐Controlled Superlattice Transformations of Oleate‐Capped Nanocubes During Solvent Removal. Issue 22 (6th May 2022)

• Record Type: Journal Article
• Authors: Lv, Zhong‐Peng; Kapuscinski, Martin; Járvás, Gábor; Yu, Shun; Bergström, Lennart
• Is Part Of: Small. Volume 18:Issue 22(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-06
• Subjects: anisotropic nanoparticles -- small angle X‐ray scattering -- superlattice transformation -- time‐dependent measurements; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202106768
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Structural transformations and lattice expansion of oleate‐capped iron oxide nanocube superlattices are studied by time‐resolved small‐angle X‐ray scattering (SAXS) during solvent removal. The combination of conductor‐like screening model for real solvents (COSMO‐RS) theory with computational fluid dynamics (CFD) modeling provides information on the solvent composition and polarity during droplet evaporation. Evaporation‐driven poor‐solvent enrichment in the presence of free oleic acid results in the formation of superlattices with a tilted face‐centered cubic ( fcc ) structure when the polarity reaches its maximum. The tilted fcc lattice expands subsequently during the removal of the poor solvent and eventually transforms to a regular simple cubic ( sc ) lattice during the final evaporation stage when only free oleic acid remains. Comparative studies show that both the increase in polarity as the poor solvent is enriched and the presence of a sufficient amount of added oleic acid is required to promote the formation of structurally diverse superlattices with large domain sizes. Abstract : Time‐resolved small‐angle X‐ray scattering (SAXS) measurements of nanocube superlattices in evaporating droplets and the correlated experimental data to multi‐scale simulations are performed. With the presence of poor‐solvent and free oleic acid, a tilted face‐centered‐cubic ( fcc ) superlattice forms at maximum polarity. An unusual tilted face‐centered cubic to regular simple‐cubic ( sc ) lattice transformation with a 10% droplet volume increase occurs when only free oleic acid remains.