Water-dispersible polyaniline-carbon nanotubes composites with interface covalent bond and their enhanced electrochemical and electrochromic properties

The water-dispersible electrochormic nanocomposites, polyaniline (PANI) connected multi-walled carbon nanotubes (MWCNTs) by covalent bond were synthesized through a grafting polymerization process of aniline monomer with functionalized MWCNTs. N,N ′-dicyclohexylcarbodiimide (DCC) was used as dehydrant for functionalization process of MWCNTs with p -phenylenediamine (PPD). The transmission electron microscope (TEM), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) were used to study the morphologies, thermal stabilities and chemical structures of the nanocomposites, respectively. The UV-vis absorbance spectra and cyclic voltammetry behaviors of nanocomposites were tested by UV-vis spectrometer and electrochemical workstation, respectively. It is shown show that PANI-MWCNTs nanocomposites not only exhibit good water solubility, but also exhibit excellent film-forming properties. The results confirm that the π-π interactions and interfacial covalent bond between PANI and MWCNTs endow PANI-MWCNTs excellent electrochemical and electrochromic properties. The conductive network composed of PANI and MWCNTs can significantly improve the ion transports, electron conduct and electrochromic performance of PANI. The PANI-MWCNTs-0.6% nanocomposite film shows highest optical contrast value (0.78) and shortest response time (3.8 seconds for coloring and 3.2 seconds for bleaching) among neat PANI and PANI-MWCNTs nanocomposites.