A Physical Method of Fabricating Hollow Polymer Spheres Directly from Oil/Water Emulsions of Solutions of Polymers

Summary: A new physical method of fabricating hollow spheres from different polymers has been developed. In this method, emulsions were prepared by mixing organic solutions of polystyrene, poly( D , L ‐lactide‐ co ‐glycolide) (PLGA), and bacterial poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) (PHBV), water, and surfactants. The evaporation of solvents at room temperature caused a phase separation that eventually yielded hollow spheres. Molecular weights, concentrations of polymers, and the natures of surfactant and solvent were important aspects of hollow sphere formation and structure. A mechanism for the formation of hollow spheres is proposed based on observations made using an optical microscope equipped with a digital camcorder and using scanning electron microscopy images of hollow spheres obtained under different conditions.A scanning electron microscopy image of a broken smaller hollow sphere prepared using a 7 wt.‐% polystyrene solution (diameter of the sphere ∼10 micrometers).