Flexible self-assembled polyelectrolyte thin films based on conjugated polymer: Quartz cristal microbalance dissipation (QCM-D) and cyclic voltammetry analysis

Abstract

Abstract The fabrication of LbL (layer by layer) self-assembled thin films is attracting attention for various applications. Hence, the detailed characterization of these films is very vital. In this study, interaction between the conjugate/non-conjugated polyelectrolyte pairs, final film compositions and viscoelastic behavior of the LbL multilayer thin films are determined using the quartz crystal microbalance dissipation (QCM-D) technique. Firstly, anodic color changing polyaniline (PAni) based LbL films as electrodes are coated on flexible PET-ITO substrate and extensive characterizations are performed. Secondly, electrochemical characterization of these films in LiClO4/PC electrolyte is carried out. It is found from QCM-D and UV–vis analyzes that the films can be successfully coated on PET-ITO surface. Film thicknesses of (PAni/PAA)10, (PAni/PAA)20 and (PAni/PAA)40 films are determined from SEM images and they are found to be approximately 160, 240 and 410\u2009nm, respectively. Ra roughness values of the same films are determined to be 6.56, 14.4 and 13.7\u2009nm from AFM analysis. Also, cyclic voltammetry (CV) analysis reveals a significant reduction and oxidation peaks of the electroactive polymer. It is observed that (PAni/PAA)20 LbL film efficiently changed blue/green to light yellow/transparent color in LiClO4/PC liquid electrolyte over the potential range from −0.1 to 0.5\u2009V vs Ag wire.