Cette conférence sera prononcée (en anglais) par le Professeur Mark T. McDermott de l'Université de l'Alberta.
The use of diazonium salts to chemically modify graphitic carbon surfaces dates back to the early 90s. Since then these types of regents have been used to tailor the surface chemistry of a variety of materials. Our interest in thin gold films for biosensing lead us to explore the structure and properties of diazonium derived aryl films on gold. The resulting aryl films are anchored to the gold surface via a stronger interaction than the gold-sulfur bond of a thiol-derived self-assembled monolayer. Another important characteristic is the ability to control the thickness of the films from mono-to multilayers by tuning the electrochemical deposition conditions. We have conducted a number of studies to probe the stability of diazonium-derived films on gold as well as the nature of the interaction. Nitrobenzene layers from the corresponding thiol and diazonium cation were directly compared. Under a number of conditions, diazonium derived films are more stable than the thiolate counterpart. This led us to explore films consisting of both thiol-derived and diazonium-derived components. We have found interesting reactivity between thiolate monolayers and diazonium cations, which will be discussed. Finally, we have utilized diazonium cations to tailor the surface chemistry of nanoparticles. Diazonium derived films of gold nanoparticles enable the probing of the nature of interaction using surface enhanced Raman spectroscopy. These reagents are also useful in controlling the chemistry of non-metallic nanoparticles. We have used this chemistry to modify cellulose nanocrystals (CNC) which enables their incorporation into polymers. The resulting nanocomposite materials exhibit enhanced mechanical properties.