My primary research efforts are directed toward understanding how silanes bond to
metal surfaces at the molecular level. Silanes are used as adhesion promoters
between an organic coating and an inorganic substrate. They have the general
structure XnSiR4-n, where R is an organofunctional group chosen for its
compatibility with the organic overlayer and X is a hydrolyzable group that
eventually forms a metal-siloxane bond (Si-O-metal). We are characterizing the
bonding of silanes that have various organofunctional groups and single or
multiple hydrolyzable groups. Titanium is one of the substrates being used
because it is a biocompatible material.
We use glancing incidence FTIR to characterize vibrational frequencies at the silane-metal interface. This technique allows us to determine whether an Si-O-metal bond forms, and it can be used to find the bond angle. Concentrations and oxidation states of the metal and atoms in the adsorbed silane layer are determined using XPS. This technique is also used to confirm the bonding configuration of the silane. Our long-term goal is to understand the process of adhesion promotion at a molecular level and to apply this knowledge to improve macroscopic adhesion phenomena. We will also tether protein molecules to the silane layers to change the biocompatibility of the surface.
"A Comparative Analysis of Trimethylmethoxy- and Trimethylchloro- Silanes Bonding on Copper Surfaces", S. Mishra and J. J. Weimer, Journal of Vacuum Science & Technology A 13(3) (1995) 1281.