Electrochemical deposition of polypyrrole films on organosilane-modified ITO substrates

We report in this work the organosilane modification of ITO substrates and subsequent electrodeposition of polypyrrole films. First, n-hexyltrichlorosilane (HTCS) and 6-(1'-pyrrolyl)-n-hexyltrichlorosilane (PyHTCS) were grafted on ITO substrates. The resulting monolayers were qualified by X-ray photoelectron spectroscopy, contact angle measurements and cyclovoltammetry, and they were found to be dense and well-covering. Second, pyrrole was electrochemically polymerized on modified ITO substrates in acetonitrile and aqueous solutions. Chronoamperometry was used to study the effect of the monolayers on polypyrrole growth kinetics. PyHTCS monolayers, compared to bare substrates, accelerate the polymer growth while HTCS monolayers delay and slow down the polymer growth. Qualitative peel tests and scanning electron microscopy (SEM) further evidenced the beneficial effect of PyHTCS monolayers. Polypyrrole grown from PyHTCS monolayers were found to be more uniform and more adherent, compared to bare and HTCS-modified ITO substrates. Cyclic voltamograms gave some additional indications in this sense. UV spectroscopy revealed differences in polymer quality arising from growth solutions: acetonitrile leads to better quality polymer films than aqueous solutions. (C) 2003 Elsevier Science B.V All rights reserved.