Fabrication of silicone oil microcapsules with silica shell by miniemulsion method

Silicone oil microcapsules with thin silica shell (about 20 nm in thickness) were readily prepared by miniemulsion technique. The emulsion droplets consisting of tetraethoxysilane (TEOS), dimethylsilicone fluid and octadecyltrimethoxy (OTMS) were first stabilized in water with sodium laurylsulfonate/triton X-100 (SLS/OP-10) as surfactants and subsequently aged under stirring at pH value of 7.5, during which the silica shell formed through hydrolysis and condensation of TEOS/OTMS at the oil droplet/water interface. The obtained microcapsule latex had a solid content of as high as 17.6 wt% and very good long-term storage stability, which are absolutely benefit for practical application. The microcapsule size, around at 200 nm, was slightly changed with the mass ratios of SLS/OP-10 and TEOS/OTMS. The silicone oil microcapsules were directly embedded into waterborne coatings and showed a good slow-releasing property.