Droplet evaporation on super liquid-repellent surfaces: A controllable approach for supraparticle fabrication

Supraparticles are agglomerates of nano- and/or microparticles with sizes ranging from tens to hundreds of microns, making them more accessible for handling and recovery than the building blocks. Supraparticles not only inherit the properties and functions of primary particles but also exhibit characteristics such as high porosity, large specific surface area, and improved functionalities, which can be attributed to the synergism, coupling, and co-localization among the constituents. Therefore, supraparticles hold promising applications in catalysis, drug delivery, sensing, etc. Among the various synthesizing strategies, evaporating droplets on a liquid-repellent surface is proposed as an effective approach to fabricate supraparticles with unique structural features and functions. The boundary conditions of such droplet-confinement methods significantly drive the formation of supraparticles by reducing or avoiding the use of solvents or processing liquids, which further accelerates the development and utilization of supraparticles. This paper presents an overview of recent developments in the fabrication of supraparticles by evaporating droplets on liquid-repellent surfaces. The review focuses on the evaporation processes on lubricant and superhydrophobic surfaces, structural regulation, and applications of supraparticles. Finally, an outlook on the future directions of evaporation on liquid-repellent surfaces mediated supraparticle fabrication is presented.