Template assisted synthesis of organic, inorganic and organic-inorganic hybrid hollow spheres

The development of new materials has a strong demand for increased functionality even on the level of the single particles. A good combination of functionalisation and miniaturisation are hollow spheres which consist of a solid organic or inorganic shell which encloses a gas filled cavity. Due to this structure lightweight fillers and spheres with improved properties can be obtained. This thesis presents the synthesis of organic, inorganic as well as organic-inorganic hybrid hollow spheres of titanium dioxide by the template sacrificial method using microcapsules as templates. Described is the synthesis of melamine-formaldehyde-capsules enclosing tetradecane as a model core substance and their subsequent coating with titanium dioxide by the thermal hydrolysis of titanium oxysulphate. After burning out of the microcapsules or extraction of the tetradecane inorganic or organic-inorganic hybrid hollow spheres are formed. Important points in the investigation of the microencapsulation and the coating with titanium dioxide were the control of the size and the wall thickness of the hollow spheres as well as the development of a fundamental understanding of the basic mechanisms and processes.