Confining the polymerization of aniline to generate yolk-shell polyaniline@SiO2 nanostructures

The polymerization of aniline was realized in a confined space by using CeO2 nanoparticles as reactive templates that were encapsulated by SiO2. The weak solubility of CeO2 in acidic solution, resulting in the slow release of Ce4+ ions with a high oxidizing potential, and the porous structure of the SiO2 shell allowed an equilibrium to be established between the diffusion of aniline inward and Ce4+ ions outward from the shell, and the polymerization of aniline in the cavity. The influence of the shell thickness, reaction temperature and aniline concentration on the generation of the yolk-shell nanostructures was investigated in detail. By virtue of the excellent photothermal property of polyaniline that was confined in the SiO2 shell, the product was applied in drug loading and photothermal release using 5-fluorouracil as a representative anticancer drug.