Thin films inverse-opal

Scientists also have learned how to mimic the surface of a butterfly wing. Polystyrene beads and smaller silica nanoparticles are suspended in water and mixed thoroughly using ultrasound. When a glass slide is dipped into the suspension and slowly withdrawn, a thin film forms on the glass surface. This film is a regular array of beads encased in a matrix of nanoparticles. Heating the film destroys the polystyrene beads but leaves the silica web intact. The result is a silica inverse opal film. 

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