Pickering emulsions stabilized by shape-controlled silica microrods

Silica microrods with aspect ratios (AR) varying from 1 to 16 but similar surface chemical characteristics are synthesized and their potential in preparing stable oil-in-water Pickering emulsions is explored. The stability of hexadecane/water emulsions is found to strongly depend on the AR and concentration of particles. Emulsions stabilized with these silica microrods are quiescently stable for quite a long period of time (over months), while emulsions with spherical particles of similar diameters destabilize after only dozens of hours. The superior stabilization efficiency of microrods with larger ARs is attributed to their higher steric hindrance, interface adsorption energy and capillary forces.