Glass Surface Chemistry - Understanding Effects of Alkali Ions on Water Activity on Glass

NON-TECHNICAL DESCRIPTION: Although multicomponent silicate glasses are involved in a variety of advanced technical applications, little is known about its surface chemistry in humid ambience. Thus, researchers, engineers and manufacturers must rely on literature and analytical methods relevant to amorphous silica to understand complex glasses even though it is clear that the surface chemistry of multicomponent silicate is quite different than silica. It is the thesis of this study that the structure and reaction of water films on silicate glasses are a function of the glass surface composition as well as the process through which the surface is created and the presence of applied or residual surface stress. This study consists of a series of carefully-designed experiments to test this hypothesis. The outcome of this research will benefit not only the glass science field, but also other engineering technologies, manufacturing, and life science research. Considering the broad range of engineering and science technologies that work with glass, it is an ideal medium through which to educate the broader community about materials, in general. This research is being integrated with education by participating in a summer Research Experiences for Undergraduates (REU) program, delivering short courses at a historically black university, mentoring undergraduate students as well as underrepresented minority students on research projects, and introducing young women from high school into research.

NON-TECHNICAL DESCRIPTION: The over-arching hypotheses of this study are: (1) the presence of local stress, whether intrinsic, applied, residual or due to local atomic/molecular structure, is a factor in determining the water layer structure, its adhesion and its reactivity, and (2) water molecules on multicomponent silicate glasses form a highly-structured interfacial layer, including hydration of metal ions, which acts as an integral part of the glass surface. Non-linear laser spectroscopy and advanced thermodynamic measurements are being used to directly measure the thickness, structure and energy of the chemisorbed as well as physisorbed water layer on multicomponent glass surfaces with varying concentrations of alkali ions. This information about the adsorbed water layer is being related to the adhesion and friction-induced dissolution of multicomponent glass surfaces in humid ambience.