Microencapsulation of oil in organically modified silicate glass by sol-gel process

Microencapsulation provides protection and sustained or controlled release of active core agents. The sol-gel process has opened up a new way for encapsulating oil droplets within an inorganic capsule. Silica microcapsules were prepared in silica precursor-oil mixtures/NH4OH water microemulsion system. In this step, the formation of capsules incorporating oil depended strongly on the type of silica precursor. A spherical silica microsheres were only obtained when oligomer, synthesized by the hydrolysis and co-condensation of equiweight of TEOS (tetraethylorthosilicate) and MTMS (methyltrimethoxysilane), was used as the wall materials. The particles size of silica microcapsules was in the range of 1similar to100 mum, depending on processing parameter such as a shear rate and O/W ratio etc. In controlled release system, the shell porosity is important to give an appropriate permeability, corresponding to the release rate. The pore structure, responsible for permeability, was adjusted by doping alkyl silane, and investigated with nitrogen sorption measurement.