Hybrid microballs with polystyrene cores coated by titania nanoparticles were prepared by miniemulsion polymerization. The crystallization morphology and photovoltage properties of the hybrid particles after calcination were characterized by Scanning Electron Microscope(SEM), X-ray diffraction and surface photovoltage spectra(SPS). The crystal morphology has a critical effect on the threshold. It is found that the materials become prous, the thresholds of TiO 2 particles blue-shift with their particle sizes decreasing and crystal phase changing from anatase TiO 2 to rutile TiO 2. The SPS results showed that the peak height was three times the height of common TiO 2 nanoparticles.
The core-shell particles consisting of poly(butyl acrylate)(PBA) core and silica shell were synthesized. The 3-methacryloxy propyl trimethoxysilane (MPS) was used as functional comonomer to modify the PBA latex particle surface with silanol(SiOH) groups via semicontinuous emulsion polymerization. The resulted emulsion was transferred into water/ethanol mixture without loss of stability and functionalized PBA latex was used as seeds for further silica shell growth. The coating process was achieved by Stber method, base-catalyzed hydrolysis and condensation of tetraethoxysilane(TEOS). The functionalized latex and core/shell particles were characterized by using differential thermal analysis(DTA), transmission electron microscope and light scattering. It has been confirmed that the PBA latex particles have been entirely enveloped with silica shell and the core/shell particles are monodisperse. The thickness of silica shell can be estimated by the size difference of functionalized PBA-SiO 2 core-shell particles.
