1. Study of Monolayer Formation on Alloys Ellen S
Study of Monolayer Formation on Alloys Ellen S. Gawalt Duquesne University-Department of Chemistry and Biochemistry
Surface modification or coating of metal alloys is prevalent in many industries for the purposes of adhesion enhancement, improving corrosion resistance and control of surface properties, such as wetting. However, finding a coating that adheres strongly to the alloy surface is often a process of trial and error. Understanding the chemical basis for successful attachment of thin films to alloys would help to eliminate this process and speed up the development of new or improved products such as sensors, pipeline coatings, and biomedical implants.
Overall we have found that the acidity and size of the organic headgroup play important roles in monolayer formation and more importantly, stability. For example, sulfonic acids form monolayers on stainless steel and all of its substituents but they are not stable to sonication. Therefore it is not a desirable system. Additionally, non-reactive metal oxides within the alloy do not prevent monolayer formation. For example, carboxylic acids form monolayers only on iron and stainless steel but not on any of the other components such as chromium. Below the modification is clear with an AFM of nickel oxide on the left and phosphonic acid modified-nickel on the right. The reduction in potential corrosion of the surface is easily seen by the reduction in the current measured on the surface (black is unmodified; grey is modified).