Electropolymerization of pyrrole on silanized polycrystalline titanium substrates

In this work is reported the silanization of titanium substrates and subsequent polymerization of pyrrole on the resulting substrates. First, titanium substrates were modified by n-hexyltrichlorosilane (HTCS) and 6-(1′-pyrrolyl)-n-hexyltrichlorosilane (PyHTCS). The corresponding self-assembled monolayers were characterized by X-ray photoelectron spectroscopy and contact angle measurements. They were found to be densely packed. Second, pyrrole was electrochemically polymerized on silanized titanium substrates. Chronoamperometry was used to study the growth of polypyrrole films. The polymer films were characterized by qualitative peel tests, cyclic voltametry and scanning electron spectroscopy. Polypyrrole grown from PyHTCS was found to adherent as compared to HTCS modified and bare substrates. Cyclic voltametry indicated that polymer films formed from PyHTCS have an oxidation peak potential located at higher values than HTCS-modified and bare substrates. Moreover, the films grown on the three types of substrates were found to be equally uniform. Finally, we improved the electrochemical properties of the polypyrrole films using a two-step process, electroreticulation of the PyHTCS monolayers followed by a pyrrole polymerization.