Finely formed porous silica nanoparticles and their strength evaluation

This paper reports on the precise control of the shape, size, and porosity of porous silica nanoparticles by using the atomized heating method. Self-assembly phenomenon of silica nanopowders and submicron polystyrene latex (PSL) balls was used for the fabrication. At the PSL concentration of around 3wt%, pores were uniformly arranged in sphere nanoparticles. By vacuum annealing at 1200°C for 30min, surface modification of the nanoparticles could be realized. The produced porous silica nanoparticles were subjected to strength test with a MEMS-based force sensor in a SEM. The annealed nanoparticles showed higher fracture strength by three times than the unannealed nanoparticles. Vacuum annealing would be effective as post-process for strengthening porous silica nanoparticles.