Three-dimensionally ordered array of air bubbles in a polymer film

We report the formation of a three-dimensionally ordered array of air bubbl es of monodisperse pore size in a polymer film through a templating mechani sm based on thermocapillary convection. Dilute solutions of a simple, coil- like polymer in a volatile solvent are cast on a glass slide in the presenc e of moist air flowing across the surface, Evaporative cooling and the gene ration of an ordered array of breath figures Leads to the formation of mult ilayers of hexagonally packed water droplets that are preserved in the fina l, solid polymer film as spherical air bubbles. The dimensions of these bub bles can be controlled simply by changing the velocity of the airflow acros s the surface. When these three-dimensionally ordered macroporous materials have pore dimensions comparable to the wavelength of visible Light, they a re of interest as photonic band gaps and optical stop-bands.