Hofmeister effect-driven superlattice construction via hydrophilic/hydrophobic transition of poly(ethylene glycol) ligands

Nanocrystal (NC) superlattices assembled from functional inorganic nanoparticles have received extensive attention due to their intriguing integrated properties and various potential applications arising from strong plasmon coupling interactions. However, the controllable assembly of colloidal NCs in an aqueous solution, especially for dynamical sequential growth, still remains an enormous challenge. Herein, we develop a robust strategy to realize the precisely controllable self-assembly and sequential oriented growth of gold nanoparticles (AuNPs) tethered to poly(ethylene glycol) (PEG) polymeric ligands in a salt solution through the dehydration degree of PEG ligands induced by the Hofmeister effect, thus yielding two-dimensional (2D) monolayer hexagonally-packed superlattices, three-dimensional (3D) single crystals with face-centered cubic (FCC) lattices and adjustable layer numbers, and multiply twinned superlattices depending on the initial salt concentrations. This finding will offer an efficient and robust approach for preparing functional superlattice materials with predictable internal packing symmetry and adjustable dimensions.