Nano-sized silica hollow spheres: Preparation, mechanism analysis and its water retention property

In this article, synthesis of nano-sized silica hollow spheres applying positive charged polystyrene as sacrificial templates was introduced. Firstly, nano-sized polystyrene particles were synthesized by emulsifier-free emulsion polymerization under solvothermal condition. Secondly, silica hollow nanospheres were formed through a simultaneous ‘coating–etching’ process. PVP played a key role in the evolution of nano-sized hollow spheres even if the templates were positive charged and the formation mechanism was different from that of previous studies. TEM results revealed that the morphologies of nano-sized silica hollow spheres not only strongly relied on the amount of reactant, but also the sequence of adding them. TGA illustrated that the interiors of nano-sized silica hollow spheres were not completely ‘hollow’. Brunauer–Emmett–Teller (BET) analysis showed that this material had a specific area of 399 m2/g. The water retention property of the materials was also investigated.