We have developed a ring opening polymerization method in an aqueous dispersion for the formation of latex. By encapsulating a catalyst in micelles dispersed in water, a seeded catalytic polymerization of various monomers in water was successfully performed. An amphiphilic molecule was used to form a micelle with a hydrophobic core in water. The catalyst that was encapsulated within this structure and the formed microcapsules were used as microreactors for the formation of biodegradable elastomers.