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

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).