Solution-processable, high-T-g, ambipolar polyimide electrochromics bearing pyrenylamine units

Two new pyrenylamine-based polyimides were prepared from the polycondensation reaction of N, N-di(4-aminophenyl)-1-aminopyrene with pyromellitic dianhydride (PMDA) or 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The polyimide derived from PMDA is soluble in hot N-methyl-2-pyrrolidone and can be solution-cast into a flexible and strong film. The polyimides showed high glass transition temperatures (T-g > 364 degrees C) and high thermal stability. Cyclic voltammetry studies revealed that these two polyimides were ambipolar; they showed well-defined and reversible redox couples during both p-and n-doping processes, together with multi-electrochromic behaviors. The polymer films also exhibited high coloration efficiency, high redox stability, and fast response time.