Synthesis and Characterization of Electrochromic Polyamides with Well-Defined Molecular Structures and Redox Properties


  • This work was supported by a grant from the Cross Enterprise Technology Development Program of the National Aeronautics and Space Administration (NASA). We also thank the Laboratory Directed Research and Development (LDRD) fund of Los Alamos National Laboratory under the auspices of the United States Department of Energy for their support.


In this paper we report the synthesis and characterization of a series of electrochromic polyamides (alternating copolymers). The synthesis proceeds via the condensation polymerization between amine-capped oligoaniline and acyl chlorides such as isophthaloyl dichloride, terephthaloyl chloride, azelaoyl chloride, and dodecanedioyl dichloride. Both the orthogonal tert-butoxycarbonyl (BOC) group on the oligoaniline segment and the non-conjugated aromatic or aliphatic segment on the polymer backbone play a vital role in the formation of the final polyamides with good solubility in common organic solvents. We cast thin polyamide films from their chloroform solutions and studied their electrochemical behavior and spectroscopic properties. In contrast to the polyaniline, the copolymers bearing oligoaniline segments show four distinct oxidation states, which were fully characterized using IR and UV-vis spectroscopy. The copolymer thin films also exhibit electrochromic behavior when a linear potential sweep is applied. Compared with the polyaniline, the polyamides adhere much more strongly to the indium tin oxide (ITO) coated glass and show no signs of delamination after hundreds of redox cycles in a hydrochloric acid solution. We believe that these factors make these novel polyamides very attractive as electrochromic materials.