Thermal, optical, electrochemical, and electrochromic characteristics of novel polyimides bearing the Acridine Yellow moiety

A series of novel polyimides and copolyimides were obtained by combining 2,7-dimethylacridine-3,6-diamine with one of three aromatic dianhydrides: 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) and 4,4′-tetraphthaloyl-bis(1,8-naphthalene dicarboxylic)dianhydride. The resultant polymers showed glass transition temperatures (Tg) in the range 209–331 °C and decomposition temperature (Td) in the range of 370–475 °C. The optical properties, absorption and photoluminescence (PL) of the obtained polymers were investigated in solution and in the solid state as blends with inert poly(methyl methacrylate). The polymers dissolved in NMP emitted blue or green light with the maximum emission wavelength in the range of 438–512 nm, while emitting blue light in the solid state. The electrochemical behavior of the polyimides was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). They exhibited electrochemical band gap in the range of 1.36–2.94 eV. Spectroelectrochemical experiments showed reversible switching between neutral violet and blue, blue-green, green, yellow and red colors corresponding to two reduction anion and dianion states depending on polymer backbone structure.