Influence of the Sacrificial Polystyrene Removal Pathway on the TiO₂Nanocapsule Structure

Abstract

This study demonstrates the significant influence of the polystyrene removal pathway on the TiO 2 nanocapsules obtained from PS@TiO 2 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@TiO 2 core-shell particles. Then, the creation of the empty cavity to form TiO 2 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 TiO 2 nanocapsule structure strongly depends on the sacrificial polystyrene removal pathway. The preservation of the TiO 2 nanocapsules was obtained essentially when the polystyrene was dissolved before the crystallization of the TiO 2 .

Ag Nanoencapsulation for Antimicrobial Applications

“…PS spheres can be synthesized without difficulty in various diameters and are easily removed by either dissolution in e.g. toluene, [13] THF, [14] xylene containing trimethylamine [15] or chloroform, [16] or by calcination at a minimum temperature of 500 °C. For the synthesis of silver containing hollow ceria NC (AgNO 3 -CeO 2 and Ag-CeO 2 ,Figs 1 and 2, A and B) 220 nm PS spheres were coated with CeO 2 by hydrolysis of Ce(acac) 3 in a sol-gel process.…”

“…As titania shells demonstrated such efficient control over the Ag + ion release the same synthetic approach was used to synthesize pure TiO 2 NC. [16] The emulsion polymerization resulted in 190 nm PS spheres that were coated with TiO 2 by hydrolysis and condensation of titanium isopropoxide similar to the synthetic route of Imhof (Fig. 1D).…”