Ballooning Behavior of Droplet Sizes in Pickering Emulsions Prepared by Flocculated PS Latexes

Pickering emulsions were prepared by mixing silicone oil whose methyl groups had been partly substituted by amine groups and water containing polystyrene (PS) latex particles in the presence of NaCl. The oil droplets rapidly enlarged after approximately 2 days of their preparation, and thereafter reached a steady-state size. After the ballooning behavior of the droplet growth, the droplet surfaces covered with PS latex particles were observed by a confocal laser scanning microscope. At NaCl concentrations above and below the critical flocculation concentration of the PS latex particles, the PS latex particles were flocculated into loosely packed and close-packed structures on droplet surfaces, respectively.