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.