The Interfacial Chemistry of Organic Materials on Commercial Glass Surfaces

Open Access
Author:
Banerjee, Joy
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
September 03, 2014
Committee Members:
  • Carlo G Pantano, Dissertation Advisor
  • Seong Han Kim, Committee Member
  • Karl Todd Mueller, Committee Member
  • David Lawrence Allara, Committee Member
Keywords:
  • glass
  • silane
  • silanization
  • surface analysis
  • composite materials
  • sodium
  • interfacial chemistry
  • adsorption
Abstract:
The hydrolytic stability of glass is dependent on its composition. Glasses are exposed to water during their processing and in many applications; therefore, their surface or interface with other materials must withstand hydrolytic attack. Multi-component silicate glasses are widely used but have been the least studied. In coatings-based applications, these glasses come in contact with organosilanes and organic molecules where the adsorption may be affected by surface water. For example, the influence of glass composition on the wet strength of a glass/polymer composite material is unclear, but it is presumed to be driven by the hydrolytic stability of the interfacial chemistry. Organosilanes are critical for increasing the performance of composite materials in humid environments but the precise manner by which the improvement occurs has not been verified. The current school of thought is that the application of silane coatings on a multi-component glass surface transforms the chemically heterogeneous surface into a homogenous and hydrolytically stable surface. In this study, multi-component silicate glass surfaces were silanized by both aqueous and non-aqueous methods. The effect of glass composition and surface hydration on silane coverage was quantified by X-ray Photoelectron Spectroscopy (XPS) analysis. The monolayer-level adsorption results showed that the low-sodium content glasses had greater coverage than a high-sodium content glass in dry conditions in contrast to an equivalent coverage in wet conditions. The hydrolytically-stable coverage on multi-component silicate glass surfaces by both silanization methods was found to be sub-monolayer. A thin film model in conjunction with XPS and Infrared Spectroscopy was used to probe the interfacial region of a fiberglass insulation material containing a sodium-rich multi-component silicate glass and an acrylate resin binder. Upon the application of the aqueous binder, the leaching of sodium from the glass promoted the formation of sodium carboxylate salts that were found to be detrimental to the hydrolytic stability of the interfacial region. The silanization of the glass improved the hydrolytic stability of the interfacial region by the mitigation of sodium carboxylate salt formation. The lack of interfacial failure indicated that the adsorption of the silane molecules and their interactions with the resin binder were hydrolytically stable.