Hollow composite microspheres can be prepared rapidly by Pickering emulsion polymerization initiated by ultraviolet light. Firstly, nano-SiO₂ were endowed with amphipathy and photosensitivity by grafting with 2-hydroxy-4-(2-hydroxyethoxy)-2-methyl-propiophenone (IHT-PI 659). Secondly, stable Pickering emulsion was fabricated by using this functional nano-SiO₂ particles as stabilizer. Finally, the SiO₂/polymethylmethacrylate composite microspheres with hollow structure were successfully synthesized by Pickering emulsion polymerization initiated by ultraviolet light at room temperature. The products were characterized by Fourier transformation infrared spectrum (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscope (SEM). A possible mechanism for the formation of the hollow composites by photo-initiation Pickering emulsion polymerization was also proposed.

Key words: UV initiation, Pickering emulsion polymerization, hollow composite microspheres