Microcapsules with siloxane walls formed in situ

A lipophilic cosmetic, chemical, biological or pharmaceutical active material composition is encapsulted by mixing it with a water reactive silicon compound and emulsifying the mixture in an aqueous medium under shear and in the presence of at least one surfactant, thereby forming an aqueous suspension of microcapsules having a core of the active material composition surrounded by a shell of silicon-based network polymer. The polysiloxane shell is preferably made by condensation of a tetraalkoxy- or trialkoxy-alkylsilane such as tetraethoxysilane (TEOS). The preferred active material is a sunscreen.