Silica, zirconia and titania inverse opals from latex opals as templates

The self-assembly of monodispersed spheres into ordered three-dimensional structures has recently attracted great attention. These colloidal crystals have unique properties of light propagation and are expected to have application in optical devices such as photonic crystals [1]. A rich variety of chemical approaches are available for producing monodisperse colloidal spheres. In terms of organics colloidal systems, the best established and most commonly used method is the emulsion polymerization for polymer latex In this work, the free-surfactant polymerization process has been studied to obtain submicrometer monodispersed latex spheres [2]. The latex spheres have been synthesized according to a single stage polymerization process based on the formation and growth of polymeric nucleus dispersed in an emulsion constituted by water, styrene and potassium persulfate. The synthesis began with the introduction of water and styrene under continuous stirring into a round glass bottle. Three parameters have been controlled during the synthesis: temperature, impeller speed and initiator addition. The temperature was kept at 70 ± 2 oC and a mechanical stirrer controlled the impeller speed in the range from 250 RPM to 400 RPM (±1 rpm). An aqueous solution of potassium persulfate was used as initiator with controlled addition during 24 hours. The emulsion has been kept under continuous stirring for 4 hours after the complete addition of the initiator. The form and siz