Template process is of importance in the preparation of voided inorganic microspheres. In this paper, monodispersed polystyrene (PSt) template particles with diameter of 360 nm and surface carboxyl groups was first synthesized via batch soap-free emulsion copolymerization of styrene and methacrylic acid, and the core-shell PSt/SiO₂ composite microspheres with variable shell thickness were prepared by surface modification-precursor method (PHC) and layer by layer method (LBL), respectively, and the voided SiO₂ microspheres were finally obtained by calcining the PSt/SiO₂ composite microspheres at 500 ℃ for 4 h. The morphology of the microspheres was characterized on transmission electron microscopy (TEM) and scanning electron microscope (SEM). In the PHC method, when the PSt template particles were first modified with γ-aminopropyl triethoxysilane (KH-550) followed by reaction with tetraethoxysilane (TEOS) in the mixture medium of ethanol and water, the voided SiO₂ microspheres with controllable uniformly compact shell thickness and smooth surface were received by calcining. However, the voided SiO₂ microspheres resulted from LBL method were easy broken up because of their incompact shell structure, and their surface was much rough. In comparison, PHC method was much easier and more suitable than LBL method in the manufacture of voided SiO₂ microspheres via template process.

Key words: voided SiO₂ microsphere, modified precursor method, LBL method, template process, calcination