Solvation-Layering-Assisted Formation of Highly Concentrated Colloidal Sub-10-nm-Diameter Layered Double Hydroxide Nanoparticles Using Acetylacetone

High-solid-concentration colloidal nanoparticles have become increasingly important in various applications. Herein, we report a novel colloidal system of layered double hydroxide (LDH) nanoparticles in which an organic molecule, acetylacetone, acts as a surface modifier to regulate the solvent layering, allowing highly concentrated dispersion in polar solvents (40 wt %) with optical transparency. The dispersion mechanism was systematically investigated by nuclear magnetic resonance, small-angle X-ray scattering, and acoustic spectroscopy. The results suggested that the high-density layering of the solvent on the solid surface is the origin of the high dispersibility of the NiAl-LDH nanoparticles. The dispersion of LDHs at high nanoparticle concentration will contribute to enhancing the efficiency of LDHs in applications such as catalysis, sensing devices, optical materials, and drug delivery.