Robust hybrid raspberry-like hollow particles with complex structures: a facile method of swelling polymerization towards composite spheres

Abstract

A novel robust hybrid raspberry-like TiO₂/PS hollow particles with complex double-shelled structures have been fabricated in large quantities by a facile swelling polymerization approach based on commercially available hollow polystyrene (PS) spheres. The crosslinked-PS protrusions are wedged firmly into the TiO₂ shell, making the resultant particles both chemically and mechanically robust. By simply tuning the monomer concentration, the hierarchical morphology (the size and number of protrusion) of the surfaces can be well-controlled. Due to the dual-sized hierarchical morphology, the particulate coating possesses superhydrophobicity (water contact angle ≈ 161°). Moreover, the well-compartmentalized character is similar to that of typical Janus particles. The special particles with interfacial activity can stabilize water-in-toluene (w/o) emulsions well. Meanwhile, a TiO₂ double-shelled hollow sphere with a complex structure is achieved by calcination or solvent treatment. All these unique features derived from a readily available method will endow the products with a broader range of applications.