Comparison of chemical cleaning methods of glass in preparation for silanization

The uniform deposition of a silane monolayer upon glass has been shown to r equire small amounts of water along with hydroxyl groups in an isolated or geminal configuration on the substrate surface. In order to expose these gr oups, organic compounds at the surface must be removed. We present a qualit ative evaluation of eight chemical methods commonly used to clean glass mic roscope slides in preparation for silanization. Mean contact angle of deion ized water was measured before covalent attachment of (3-mercaptopropyl)tri ethoxysilane to assess the efficacy of each procedure. Contact angles were also measured after silanization as a means of determining the uniformity a nd reproducibility of the silane monolayer. The results indicate that a 1:1 methanol/HCl wash followed by a bath in concentrated H2SO4 removes surface contaminants most effectively and allows for a very even silanization of t he glass surface. (C) 1999 Elsevier Science S.A. All rights reserved.