Cyclohexane-in-Water Emulsion as a Sacrificial Template for the Synthesis of Multilayered Polyelectrolyte Microcapsules

We report the application of cyclohexane-in-water emulsions as novel sacrificial templates for the fabrication of hollow microcapsules through layer by layer assembly of polyelectrolytes, polystyrene sulfonate (PSS) and polyallylamine hydrochloride (PAH). We demonstrate that aqueous-dispersed cyclohexane droplets can be frozen at manageable temperature by taking advantage of the unusually high melting point of cyclohexane (6°C) and used as solid templates for the layer by layer assembly of polyelectrolytes. Ethanol-assisted removal of cyclohexane from emulsions coated with eleven polyelectrolyte layers leads to the formation of hollow microcapsules preserving the spherical geometry. Majority of the microcapsules (>90%) are prepared with intact polyelectrolyte membranes as measured by the osmotic pressure induced deformation of microcapsules. This work provides a new route for the synthesis of multilayered microcapsules under mild operating conditions and would enable the use of sensitive biomolecules as building blocks.