Effect of aqueous and organic solvent ratio on the electropolymerization of bithiophene in the mixed solutions

The use of suitable ratio of water to acetonitrile could lower the onset ox idation potential of bithiophene to about 0.6 V vs. Ag/AgCl in the aqueous/ organic mixed solution. This means that bithiophene can be electropolymeris ed at very low potential in such solutions, which is usually unachievable i n pure organic media. When the current density for electropolymerisation wa s kept constant as 1.0 mA/cm(2), the electropolymerization potentials for b ithiophene could be tuned to stable values of 0.8, 0.9, and 0.94 V by keepi ng the volume ratio of water to acetonitrile as 2:1, 1:1, and 1.4, respecti vely in the mixed solution. Evidence shows that the chemical structure of p olybithiophene synthesised by this technique is very similar to that of the polymer formed in organic media. The volume ratio of water to acetonitrile has a significant effect on electropolymerization of bithiophene as well a s on the electrochemical properties and morphology of the polybithiophene f ilms. (C) 1999 Elsevier Science S.A. All rights reserved.