Tunable Micro/Nanomaterial Encapsulation in Porous Melamine Sponges by Rotational Vortexing: Implications for Functional Nanomaterial Recycling

A fully tunable encapsulation of functional micro/nanomaterials inside three-dimensional (3D) porous structures by the unique rotational vortexing operation is reported. The constantly swirling liquid flow through a porous matrix induces efficient particle stacking onto the supporting substrate fiber surface via van der Waals interaction. Homogeneous or gradient distributions of functional nanomaterials inside porous structure are achievable, depending on the relative dimensions between filling material and matrix pore size, while the vortexing duration and precursor concentration affect the total captured particle quantity. This unique stereo control over particle packing relies on gradient accumulations of colloidal particles from the exterior edge to the center by three pairs of directional filtration from two opposite faces of a cubic sponge. This material filling approach overcomes conventional obstacles such as process complexity, expensive equipment necessity, and material distribution uncertainty, which should inspire the development of filling technology for diverse stereo-architecture-related applications.