Robust hybrid raspberry-like hollow particles with complex structures: a facile method of swelling polymerization towards composite spheresElectronic supplementary information (ESI) available: Fig. S1-S3 as discussed in the text, and more experimental details. See DOI: 10.1039/c3sm52739e

A novel robust hybrid raspberry-like TiO 2 /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 TiO 2 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 TiO 2 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. The robust hybrid raspberry-like TiO 2 /crosslinked-PS hollow particles with double-shelled structure have been successfully prepared in large quantities via a facile swelling polymerization approach. Meanwhile, TiO 2 hollow spheres with complex structures are achieved by calcination or solvent treatment.