Robust Anisotropic Composite Particles with Tunable Janus Balance

We report a general emulsion approach to protrude a lobe by swelling the polymer core from a core–shell structure, achieving anisotropic Janus composite particles with tunable chemistry, shape, size, and size ratio of the two parts thus Janus balance. Oil-in-water emulsion is employed to swell a polymer core through the crack open hole within the shell, and the core protrusion is restricted in the particle/oil confined compartments enveloped with surfactant. When monomers are used as the oil solvents, cross-linking can strengthen the polymer lobe to tolerate against organic solvents. By tuning polymerization time and monomer/particle weight ratio, the size ratio of the polymer/inorganic parts thus Janus balance of the composite particles is continuously tunable across from more hydrophilic to more lipophilic. The robust anisotropic particles with tunable Janus balance can be further used as solid surfactants to tune microstructure of emulsions.