Highly porous nanocoatings tailored for inverse nanoparticle-polymer composites

A novel nanoparticle‐polymer composite is proposed, named inverse nanocomposites in this work. First, a rigid percolating scaffold of nanoparticles is formed, which is filled with a matrix and then polymerized. Targeted for use in thin‐film applications, these mesoporous nanoparticle scaffolds are prepared by combining the sol-gel chemistry of functionalized silanes with nanoparticles in dispersions. The nanoparticle coatings have high porosity, low density, good adhesion to the substrate, and interesting non‐classical properties, such as absorbency of highly viscous fluids. The porosity, which can be adjusted by changing the composition and preparation parameters, reaches 75%. The porous scaffold can be infiltrated with various fluids, including acrylic and epoxy monomers and even highly viscous pressure‐sensitive adhesives. If the monomers are polymerized after imbibition, the inverse nanocomposite is formed, consisting of a percolating particle network surrounded by a polymeric binder. Hence, the morphology comprises an interpenetrating system of two co‐continuous phases and not merely particles dispersed in a polymeric phase, as is typical for conventionally prepared nanocomposites.