ELECTROCHEMICAL AND ELECTROCHROMIC PROPERTIES OF POLY(DIALKYLSILYLENEFERROCENYLENE) FILMS

Thin films of poly(dialkylsilyleneferrocenylene) (poly(FCSiR2), R = me thyl, ethyl, n-butyl, and n-hexyl) were coated onto a platinum electro de, and their electrochemical behavior was measured while immersed in either an aqueous or organic electrolyte. The cyclic voltammograms of the films do not show the sharp symmetrical peaks expected for surface localized reactions. Instead, in 0.1 M aqueous H2SO4 there is one uns ymmetrical oxidation peak with a sharp current rise indicating that th e neutral films are poorly solvated and they become solvated when the break-in voltage of 0.54 V is reached. In the cathodic scan, the reduc tion peak is small and broad. In 0.1 M Et4NBF4/CH3CN two redox couples are observed as was previously reported for these polymers in solutio n. In this electrolyte, the lack of chemical reversibility in the redo x reaction of the film is observed. The films are electrochromic and c hange color from clear yellow (neutral) to light green (oxidized) when the applied potential is changed from 0.0 to 1.0 V. The oxidation pea k potentials shift with the size of the alkyl substituents on the poly mer.