Re‐Dispersible 1D and 2D Nanoparticle Solid Powders without any Surfactant.

Nanoparticles possess unique size‐dependent physical and chemical properties and hold considerable interest as ideal, defect‐free building blocks for nanostructured materials. However, due to irreversible and intrinsic self‐aggregation, it is challenging to obtain dried nanoparticle powders with good redispersibility. In this work, we propose a general method to increase the dispersibility of typical 1D and 2D nanoparticles, including cellulose nanowhiskers, graphene, Laponite and montmorillonite, by combining sol‐gel transitions and supercritical CO2 drying. In the resulting dried powders, the nanoparticles adopt a non‐full‐contact mode and maintain a loose packing structure formed during the gelation process; thus, they can be perfectly redispersed in water and some organic solvents under mild conditions. Such a promising strategy, without using a surfactant, deliberate surface‐modification and high energy consumption, provides a practical solution to the transportation, storage and large‐scale industrial applications of nanoparticles. Hang loose: Maintaining loose packing structures formed in the sol‐gel process is shown to be an efficient strategy to increase the dispersibility of 1D and 2D nanoparticles, including cellulose nanowhiskers, graphene, Laponite and montmorillonite. [ABSTRACT FROM AUTHOR]