Preparation of Neutrally Colorless, Transparent Polynorbornenes with Multiple Redox-Active Chromophores via Ring-Opening Metathesis Polymerization Toward Electrochromic Applications

A new electrochromic norbornene derivative containing triphenylamine groups (NBDTPAC8) was synthesized using norbornene amine and bromotriphenylamine. NBDTPAC8 was used in ring-opening metathesis polymerization to obtain poly (NBDTPAC8) using different Grubbs' catalysts and followed by hydrogen reduction to obtain poly(HNBDTPAC8). The glass transition temperatures (T-g) of poly(NBDTPAC8) and hydrogenated poly(HNBDTPAC8) were 132 and 89 degrees C, respectively. Poly (HNBDTPAC8) film exhibited a fluorescence maximum around 416 nm with a quantum yield of up to 60%. Hydrogenated poly (HNBDTPAC8) film showed excellent transparency (up to 93%). Poly(HNBDTPAC8) showed cyclic voltammetric and electrochromic behaviors similar to those of poly(NBDTPAC8). The cyclic voltammogram of a poly(HNBDTPAC8) film cast onto an indium tin oxide (ITO)-coated glass substrate exhibited three reversible oxidation redox couples at 0.69, 0.94 and 1.38 V versus Ag/Ag+ in an acetonitrile solution. The electrochromic characteristics of poly(HNBDTPAC8) showed excellent stability and reversibility, with multi-staged color changes from its colorless neutral form to green, light blue and dark blue upon the application of potentials ranging from 0 to 1.60 V. The color switching time and bleaching time of the poly(HNBDTPAC8) film were 6.2 s and 4.3 s at 1175 nm and 6.6 s and 4.4 s at 970 nm, respectively. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 3248-3259, 2011