Preparation of Mannitol@Silica core–shell capsules via an interfacial polymerization process from water-in-oil emulsion

Mannitol@Silica core–shell capsules were prepared from W/O emulsion by adding silicon precursor into the oil-continuous phase to form silica shell through interfacial polymerization reaction. The bicomponent mixture of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTS) was used as silicon precursor to form relatively thick silica shell. The reaction was triggered by the penetration of APTS from oil-continuous phase into the aqueous phase and the silica shell formed as both TEOS and APTS hydrolyzed and polymerized after diffusing through the W/O interface. The growth of the shell layer was believed to be an outside-in mode. The mannitol crystal was well sealed inside the silica capsule under an optimized condition and the leakage was successfully avoided. The Mannitol@Silica core–shell capsules own irreversible phase change character in the range of 142.1–166.2 °C with latent heat of 147.4 J/g.