Abstract
The synthesis of alumina balloons using the microcapsulation method has been investigated, and was successful in producing a transparent balloon with a diameter of 50-80μm and a wall thickness of less than 1μm. The process is as follows. 10mass% solution of polystyrene in toluene and boehmite sots of approximately 1mol/kg concentration are mixed by a homogenizer. The resultant W/O emulsion is redispersed in water to obtain a (W/O) W emulsion which produces boehmite sols encapsulated by polystyrene in water. After keeping it for 2 days at 40°C, the products are filtered, dried and then the polystyrene crust is dissolved by toluene. The resultant balloon precursors of boehmite sols are dried, fired and then the alumina balloons are obtained. In this paper, the effects of the concentration of polystyrene or boehmite sots and the addition of ethylene glycol or tricresyl phosphate on the formation of alumina balloons were discussed in detail.
