Influence of the sacrificial polystyrene removal pathway on the TiO₂ nanocapsule structure

This study demonstrates the significant influence of the polystyrene removal pathway on the TiO₂ nanocapsules obtained from PS@TiO₂ core-shell particles. In a first step, the polystyrene spheres were coated with titanium oxide via hydrolysis and condensation of the titanium precursor to form PS@TiO₂ core-shell particles. Then, the creation of the empty cavity to form TiO₂ nanocapsules was achieved by removing the polystyrene template by i) thermal decomposition of the polystyrene or ii) dissolution of the polystyrene using Soxhlet extractor followed by a thermal procedure. These pathways to remove the polystyrene were investigated by thermogravimetric studies, IR spectroscopy, transmission and scanning electron microscopy and powder X-ray diffraction. The final TiO₂ nanocapsule structure strongly depends on the sacrificial polystyrene removal pathway. The preservation of the TiO₂ nanocapsules was obtained essentially when the polystyrene was dissolved before the crystallization of the TiO₂