Titania coatings are prepared by dip coating anhydrous titanium ethoxide solutions on glass substrates. Titanium ethoxide reacts with atmospheric water during deposition and drying to form coatings with a variety of microstructures. Transparent gel layers are prepared by coating in dry nitrogen and then exposing the coating to humid atmosphere or using slow withdrawal rates. Hydrated titania particles form in coatings deposited in atmospheres with relative humidity levels greater than ≈ 15%. These coatings are typically composed of agglomerates of small particles (≈0.3 μm); increases in substrate withdrawal rate and Ti ethoxide concentration in the solution bath lead to increases in thickness, particle size and extent of agglomeration. Particle aggregation is prevented by adding hydroxypropyl cellulose (HPC) to the coating solution before deposition.
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Acknowledgemenist madet o the Donorso f the Petroleum ResearchF und, administeredb y the AmericanC hemicalS ocietyf or the supporto f this researchS. upportf rom theU niversityo f Minnesota UndergraduatRee searchO pportunitiePsr ograma nd the useo f the High ResolutionE lectronM icroscopy Center at the Centerf or InterfacialE ngineeringa re also acknowledged.