The effect of monomer and electrolyte concentrations during synthesis on the actuation of PPy(CF3SO3) films in aqueous electrolytes

Free-standing films of polypyrrole, PPy(CF3SO3), were electropolymerised galvanostatically from propylene carbonate solutions containing tetrabutylammonium trifluoromethanesulfonate of a range of pyrrole or electrolyte concentrations. The electrochemomechanical deformation (ECMD), measured in situ during cyclic voltammetry experiments, was found to increase when a higher concentration of pyrrole monomer or CF3SO3 electrolyte was used during the polymerisation. X-ray photoelectron spectroscopy was used to estimate the presence of different forms of carbon in the PPy(CF3SO3) films, including the α and β carbons of the pyrrole ring, the ‘disordered carbon’ and carbonyl carbon. These XPS results were correlated with the strains observed in ECMD measurements and the doping level estimated from N1s XPS spectra. The morphology of the films obtained for different growth conditions was also investigated by means of SEM.