Electrochemical polymerisation of thiophene derivative induced by Lewis acid: Electrosynthesis of poly[(R)-(−)-2-(3′-thienyl)ethyl-(3′,5″-dinitrobenzoyl)-α-phenylglycinate]

Films of poly[(R)-(−)-2-(3′-thienyl)ethyl-(3′,5″-dinitrobenzoyl)-α-phenylglycinate] were deposited on ITO electrodes by potentiodynamic, potentiostatic and galvanostatic methods using a (C4H9)4NBF4/CH3CN electrolyte system containing 20% boron trifluoride diethyl etherate. Polymerisation occurred as a charge dependent process at a potential of 1.4 V vs. Ag/Ag+(CH3CN). The surface morphologies of the films so-formed were examined using atomic force microscopy. The film deposited by the galvanostatic method displayed more homogeneous grain geometry and a larger superficial area than those formed by the other methods. Cyclic voltammetry revealed a well defined redox couple at the anodic region, attributable to polymer p-doping, and a poorly defined redox pair at the cathodic region, attributable to the reduction of the nitro group. The polymeric films obtained were yellow in colour (λmax 425 nm) in the reduced state and light blue (λmax 745 nm) in the oxidised state.