Thin functional polymer films by electropolymerization

Abstract

Intrinsically conducting polymers (ICPs) have been widely utilized in organic electronics, actuators, electrochromic devices, and sensors. Many potential applications demand the formation of thin polymer films, which can be generated by electrochemical polymerization. Electrochemical methods are quite powerful and versatile and can be utilized for investigation of ICPs, both for educational purposes and materials chemistry research. In this study, we show that potentiodynamic and potentiostatic techniques can be utilized for generating and characterizing thin polymer films under the context of educational chemistry research and state-of-the-art polymer research. First, two well-known bifunctional monomers (with only two linking sites)—aniline and bithiophene—and their respective ICPs—polyaniline (PANI) and polybithiophene (PBTh)—were electrochemically generated and characterized. Tests with simple electrochromic devices based on PANI and PBTh were carried out at different doping levels, where changes in the UV-VIS absorption spectra and color were ascribed to changes in the polymer structures. These experiments may attract students’ interest in the electrochemical polymerization of ICPs as doping/dedoping processes can be easily understood from observable color changes to the naked eye, as shown for the two polymers. Second, two new carbazole-based multifunctional monomers (with three or more linking sites)—tris(4-(carbazol-9-yl)phenyl)silanol (TPTCzSiOH) and tris(3,5-di(carbazol-9-yl)phenyl)silanol (TPHxCzSiOH)—were synthesized to produce thin films of cross-linked polymer networks by electropolymerization. These thin polymer films were characterized by electrochemical quartz crystal microbalance (EQCM) experiments and nitrogen sorption, and the results showed a microporous nature with high specific surface areas up to 930 m2 g−1. PTPHxCzSiOH-modified glassy carbon electrodes showed an enhanced electrochemical response to nitrobenzene as prototypical nitroaromatic compound compared to unmodified glassy carbon electrodes.