Fused anti-soiling and anti-reflective coatings

Abstract

A method for applying a coating to a surface includes the step of providing a reaction mixture comprising a silicon alkoxide and an alcohol. A reaction limiting amount of water is added. The silicon alkoxides and water are allowed to react to form silica precursor particles during an initial reaction period. A coating precursor composition is prepared by adding an acid soluble in the alcohol to the reaction mixture during a second reaction period after the initial reaction period. The precursor silica particles grow to form silica nanofeatures having a major dimension that is larger than a major dimension of the silica precursor particles. The coating precursor composition is applied to a surface, and the alcohol and water are allowed to evaporate and the silica nanofeatures to adhere to the surface and form a nanostructured layer on the surface. A coating precursor composition and a coated article are also disclosed.

We claim: 
     
         1 . A coating precursor composition, comprising a sol-gel comprising water, alcohol, and silica nanofeatures, the silica nanofeatures comprising at least one selected from the group consisting of silica spheres and silica rods, and being the reaction product of silicon alkoxide and water. 
     
     
         2 . A coated article comprising a silica substrate and a continuous coating of silica nanofeatures, the coating having a thickness of between 0.01 μm-1 μm, the nanofeatures having a diameter of 10 nm-500 nm, a width of 200 nm-1500 nm, a height of 10 nm-100 nm, and a spacing of 1 nm-500 nm. 
     
     
         3 . The coated article of  claim 2 , wherein the silica nanofeatures are silica rods.