Decomposing Oil-Soluble Initiators in Particles: A Template-Free Method for the Preparation of Hollow Polymer and Silica Particles

[Image: see text] Nanovoids contained in hollow particles render them potential drug carriers. However, conventional methods for the synthesis of these particlhes involve complex processes. In this study, we developed a template-free method for the synthesis of hollow polymer and silica particles by initially preparing polystyrene core particles containing 2,2′-azobis(2-methylbutyronitrile) (V-59) through soap-free emulsion polymerization. The subsequent generation of nitrogen gas inside these particles upon the decomposition of V-59 at 70 °C led to the formation of voids. In addition, silica shells were synthesized on the surfaces of the V-59-containing polystyrene core particles through a sol–gel reaction at 40 °C, following which voids were formed by the decomposition of V-59 at 70 °C. The developed method involves straightforward steps and is environmentally friendly, as it does not require the use of surfactants, organic solvents, or templates.