Partially functionalized Janus ZnO spheres prepared by protecting mask techniques

Asymmetric Janus ZnO spheres with partially attached PS spheres were prepared by both protecting layer mask technique and Pickering emulsion template in presence of polyelectrolyte (poly(allylamine hydrochloride)). The scanning electron microscopy images showed that the surface of ZnO sphere was clearly divided into two parts, one of which was densely packed with PS particles, and the other one was bare. As compared with Janus ZnO formed by Pickering emulsion, the protecting layer mask technique gave rise to more regular masked area on the ZnO spheres, thereby producing quite regular morphology of the PS patterned. More importantly, this approach provided a facile way to tune the Janus balance by controlling the geometry of the Janus ZnO spheres, which was achieved by adjusting the thickness of the wax layer.