RTILs VS VOCs : the role of the electropolymerization medium on the features of inherently chiral polymer films

A typical drawback of electrochemical processes consists in the employment of volatile organic solvents (VOCs), which imply safety problems and require the addition of high amounts of a supporting electrolyte to obtain the necessary conductivity. Both problems could be overcome by shifting to non-conventional media such as room temperature ionic liquids (RTILs). In fact, RTILs present various desirable advantages over molecular solvents, including negligible vapour pressure, high intrinsic conductivity without addition of supporting electrolyte and easy recyclability. Moreover, specifically dealing with electropolymerizations, preliminary studies[1,2] point to ionic liquids, both as such and as cosolvents, significantly improving the regularity and the mechanical and morphological properties of the conducting films to be employed e.g. in the energetic, optoelectronic, and sensoristic domains. In this context, we present the results obtained in our research work, concerning a class of inherently chiral polymer films[3], studied and characterized as racemates and as separated enantiomers, by means of cyclic voltammetry and electrochemical impedance spectroscopy, together with SEM imaging. In order to finely discriminate among the racemate and enantiomer film properties, and above all to achieve optimized enantiomer electrode surfaces for applications as chiral sensors, reproducibility is a necessary but hard task. In this frame, the present work is aimed to compare the polymer features obtained in different conditions (i.e., RTILs vs VOCs, on various electrode surfaces and for increasing thickness of the electrodeposited films) to select the best working medium for the preparation of the electroactive films. [1] F. Endres, A.P. Abbott, D.R. MacFarlane, Electrodeposition from Ionic Liquids, 2008, Wiley-VCH, ISBN 978-3-527-31565-9 [2] A.Pietrzyk, W.Kutner, R.Chitta, M. E. Zandler, F. D’Souza, F. Sannicolò, P.R. Mussini, Anal. Chem., 2009, 81(24), 10061-10070. [3] F. Sannicolò, S. Rizzo, T. Benincori, W. Kutner, K. Noworita, J.W. Sobczak, V. Bonometti, L. Falciola, P.R. Mussini, M. Pierini, Electrochim. Acta, 2010, 55(27), 8352-8364.