Templated synthesis of silica hollow particles by using spray pyrolysis

It is commonly accepted that one hollow particle is formed from one droplet in conventional spray pyrolysis or drying. Therefore, the particles size distribution is closely related to the droplet size distribution. In this report, however, a new aerosol process was proposed, in which multiple hollow particles were produced from one liquid droplet with the aid of salt and polystyrene (PS) bead. In this process, the particles size and size distribution were determined by the PS beads, not by the droplets. Silica hollow particles of 160 nm in diameter and 10 nm in shell thickness were prepared after washing off the salt with water. Geometric mean dispersion of hollow particles were 1.02, whereas the geometric mean deviation of droplets was 1.3. The role of salt was to keep nano-size hollow particles desegregated while the PS template beads were burnt off at 500degreesC.