Preparation of novel hybrid inorganic-organic hollow microspheres via a self-template approach

BACKGROUND: Hollow microspheres, especially biodegradable polymeric microspheres, have attracted considerable attention due to their particular characteristics. Up to now, microspheres have been prepared via various strategies, for instance the template synthesis method and the self-assembly process. However, economic, novel and simple methods to prepare hollow microspheres are still being sought. RESULTS: Phosphazene-containing microspheres, which contain self-assembled core-shell structures, were prepared at high colloid contents using an ultrasonic bath via a self-template approach. Along with the controlled self-degradation of the internal core, the corresponding hybrid inorganic-organic hollow microspheres appeared. The mechanism was evidenced by means of transmission and scanning electron microscopy, cross-polarization with magic angle spinning NMR, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. CONCLUSION: It was clarified that the phosphazene-containing microspheres could be formed and stably dispersed without aggregation even at high colloid contents using the ultrasonic bath method and the microspheres contain self-assembled core-shell structures. Along with the controlled self-degradation of the internal core, the corresponding hollow microspheres appeared. The mechanism of this preparation is of great significance because it is completely different from the conventional template synthesis method and the self-assembly process. The absence of any stabilizing agent and special templates might inspire creative imagination in the design of new morphologies of micro- and nanostructures. (c) 2007 Society of Chemical Industry.