Functionalization of titanium surfaces with a simple electrochemical strategy

The control of the interface properties of titanium (Ti) and related alloys is of prime significance in dental implantology to enhance the biological compatibility of screws. In this work, we have investigated the use of electrochemical grafting of diazonium salts to modify the surface of titanium samples to propose a simple, low-cost, and reliable functionalization technique for titanium and titanium-based alloys. We have explored this electrochemical procedure by using two model salts in acidic aqueous solution, namely 4-nitrobenzenediazonium tetrafluoroborate (NBD) and 4-carboxybenzenediazonium tetrafluoroborate (CBD). A thorough chemical characterization of functionalized Ti surface enabled us to ascertain the presence of nitrophenyl or carboxyphenyl groups at titanium surfaces. The influence of the scan rate during the electrografting procedure on the properties of the modified surfaces was also analyzed by XPS. From our results, NBD is most probably electrografted according to an island-like model, as the equivalent thickness of the adsorbed layer, estimated from XPS measurements, is below one monolayer, while, CBD is electrografted in few multilayers of 2 to 3 nm thickness, depending on the scan rate used during electrografting.