Hydrophobic polymer films, having an aqueous phase distributed throughout the matrix, were formed by polymerizing a solution of dodecyl acrylate and 1,6 hexanediol diacrylate containing nanometer-sized drops of water stabilized by sodium bis(2-ethylhexyl) sulfosuccinate (ACT). Photopolymerization-incluced aggregation of the water drops and/or phase separation occurred, as the initially clear solutions became opaque films. The polymerized films became clear, as the relative humidity was reduced. Clear films still contained 20-50% of the initial water. The transition from opaque to clear films was reversible provided that the film did not become completely dry and form cracks. (c) 2007 Wiley Periodicals, Inc.