Janus Anisotropic Hybrid Particles with Tunable Size from Patchy Composite Spheres

We have developed a facile approach to synthesize anisotropic Janus hybrid particles by selective modification of bulgy patches on the composite spheres, which are in situ grown by phase separation during seeded emulsion polymerization. Janus particles are achieved by dissolution of the seed polymer particles. It is the key to control phase separation to form multiple bulges and tune their size by pH and monomer fraction. The size of the Janus particles is continuously tunable from submicrometer to nanometer scale. They can be massively synthesized since many bulges are derived from one seed sphere.