Inward template synthesis of intact hollow spheres

A facile and general one-step approach is presented to synthesize hollow spheres with varied composition by an aerosol-assisted solvent evaporation process. The monomer of ethyl-2-cyanoacrylatemide contained in the aerosol droplets can form an outer shell by a fast polymerization around the droplets. Materials inside the droplets further grow inwardly against onto the interior surface of the first shell forming another shell forming composite hollow spheres. The hollow spheres are derived by dissolution of the outer shell, therefore the intact shell can be well preserved. Many approaches can be exploited forming the second shell for example sol-gel process of oligomers and phase separation from polymer solutions. Microstructure of the hollow spheres can be tuned from smooth to porous. The methodology is general.