Study of structural and electrochemomechanical properties of aniline/2 metoxianiline copolymers

W. ARMADA; G. CONTRAFATTI; L. LIZARRAGA; E. M. ANDRADE; F. V. MOLINA

Isla de Oleron

Conferencia; 2nd international conference on the Electrochemical Promotion of Catalysis and its Applications; 2008

Poly(aniline) and its derivatives undergo volume changes upon redox cycling, specially in the first redox step, when going from the fully reduced form, leucoemeraldine, to the intermediately oxidized one, emeraldine. In this work, structural and electrochemomechanical properties of copolymers of aniline (ANI) and 2-methoxyaniline (MOA) were studied and compared with their corresponding homopolymers. Experimental Copolymers were electrosynthesized[1] in variable ratios and characterized by elemental analysis, IR spectroscopy, and UV-MALDI-TOF mass spectrometry. The electrochemomechanical behaviour was studied on thick films (200 µm) through direct microscopical observation of volume changes caused by redox switching from leucoemeraldine to emeraldine state in a sulphuric and a perchloric acid media using a video recorder. Results and Discussion The copolymer composition obtained from elemental analysis was correlated with the feed composition through the Mayo-Lewis equation[2], confirming the higher reactivity of MOA. Figure 1 shows the volume changes in sulphuric acid media when cyclic voltammetry was applied for a copolymer film that was synthesized from a feed composition ANI:MOA 100:1. The observed volume changes for different copolymers during the first cycle were strongly dependent on the polymer composition, but also on the electrolyte anion. The behaviour revealed different anion/polymer interactions as the copolymer composition was changed. Besides, it was found that electropolymerized films had, for the same voltammetric charge, smaller volumes as the MOA/ANI ratio increased.