General Synthetic Route toward Functional Hollow Spheres with Double‐Shelled Structures

Double agent: Controlled sulfonation of polystyrene hollow spheres gives hydrophilic layers with sulfonic acid groups that allow the formation of a wide variety of functional composites. In this way, double-shelled hollow spheres have been prepared in one step by using such sulfonated polystyrene hollow spheres as templates (see TEM image of titania sphere).