Thick silicate glass film by an interfacial polymerization

A silicate glass film of 2–20 µm in thickness has been formed on a fused quartz substrate by a sol-gel process using an interfacial polymerization technique. A partially hydrolyzed silicon alkoxide was dissolved in hexane and brought into contact with ammonia water in a cylindrical Teflon container. A silica gel film formed at the interface between the two immiscible liquids by the polycondensation of the partially hydrolyzed silicon alkoxide was gently placed on a substrate at the bottom of the container, by draining the liquid. The crack free gel film was dried in an ambient atmosphere and dip-coated with boron ethoxide, followed by sintering in an oven at 1250°C for 1 h. The glass film thus obtained was highly transparent and 2–20 µm in thickness depending on the concentration of the precursor solution and the pH of ammonia water.