Electrochromic polyaniline/aramid nanofiber composites with enhanced cycling stability and film forming property

Polyaniline (PANI)/hydrothermal treatment aramid nanofibers (HANFs) nanocomposites were synthetized by in situ chemical oxidation polymerization of aniline monomers onto HANFs. The morphologies as well as the chemical structures and thermal stabilities of the composites were studied using scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). The results confirmed the core–shell structural of the obtained nanocomposites and the interactions between PANI and HANFs. The nanocomposites could be well dispersed in water and show excellent properties of film forming. The drop-coated nanocomposites films exhibited outstanding adhesion with the ITO glass and remarkably enhanced electrochromic properties. The optimized nanocomposite film with the PANI/HANFs ratio of 70/30 wt/wt% showed higher optical contrast values (58.1%), and faster response time, which was 1.1 s for bleaching and 1.3 s for coloring than those of pure PANI. And the electrochromic cycling stability investigation revealed that the nanocomposite film showed much more improved durability and retained 83.6% of the optical contrast value even after 500 coloring-bleaching cycles. The data indicated great promise for the novel aramid nanofiber-based nanocomposite as a potential electrochromic material with excellent properties.