Polyethylenimine-assisted synthesis of hollow silica spheres without shape deformation

Abstract

A self-templating method has been employed to explore both the concentration and size of template silica particles suitable for synthesis of rigid hollow spheres. Herein, polyethylenimine (PEI) was used as a surface protecting layer for the silica particles whose interiors were selectively dissolved in water to form the hollow particle structure. The morphology of hollow silica particles formed by the silica dissolution strongly depended on total surface area of the PEI-modified particles in aqueous solution. Spherical hollow particles were obtained in the range of low total surface area. In the range of high total surface area, however, hollow particle structures were deformed during the synthetic processes including the silica dissolution, centrifugation, and drying processes. The deformation phenomenon of hollow particles was explained using relative dimension of shell thickness to particle diameter. According to the total surface area of template silica particles studied above, the concentration of silica-coated gold nanorod in water was adjusted to selectively dissolve the particle interior, succeeding in hollow spherical particles containing a gold nanorod.