Novel polyimides containing flexible carbazole blocks with electrochromic and electrofluorescencechromic properties

A series of polyimides (PIs) were prepared by polycondensation of a diamine monomer with five anhydrides (1,2,4,5-benzenetetracarboxylic anhydride (BTA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTD), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BTD), 4-[(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)oxy]-1,3-isobenzofurandione (DDII), and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BPTD)), which have anodic electrochromic (EC) properties. These PIs not only show good solubility and thermal stability, but also demonstrate stable electrochemical oxidation behavior and good EC properties, and the highest retained electroactivity reaches 99% after 600 cycles. In addition, the series of PIs exhibit excellent electrofluorescencechromic (EFC) properties. Therefore, the novel materials will contribute to the application of EC or EFC displays in the future.

Recent advances in triphenylamine-based electrochromic derivatives and polymers

Triphenylamine-containing electrochromic materials with great potential applications in low energy-consumption displays, light-adapting mirrors in vehicles, and smart windows have experienced an exponential growth of research interests. In this review, the newly developed triphenylamine-based derivatives and polymers are reviewed and elaborated.

Electrochromic and electrofluorochromic polyimides with fluorene-based triphenylamine

A series of novel polyimides (PIs) based on N,N-di(4-aminophenyl)-2-amino-9,9-dimethylfluorene and various dianhydrides were synthesized. These PIs were amorphous and readily soluble in many solvents. They displayed outstanding thermal stability and high glass transition temperatures (269–374°C). The polymer films showed reversible electrochemical redox and satisfactory electrochromic performance with long-term stability, high coloration efficiency, and acceptable switching times. The PI derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride exhibited maximum fluorescence at 400 nm with quantum yields up to 28.1%. Furthermore, the fluorescence can be effectively electroswitched between “on” and “off” states, exhibiting a high contrast ratio of 75.

A series of organosoluble polyamides with 4-(dimethylamino)triphenylamine

A series of novel aromatic polyamides containing 4-(dimethylamino)triphenylamine were prepared via the polycondensation reactions of the newly synthesized dicarboxylic acid, 4,4′-dicarboxy-4″-(dimethylamino)triphenylamine, and various diamines. Introduction of 4-(dimethylamino)triphenylamine units along the polymer chain enhanced the solubility of the polymers. The 10% weight loss temperatures of these polymers ranged from 432°C to 471°C with the char yields more than 63% at 800°C under nitrogen atmosphere. The polymers displayed low oxidation potentials because of the incorporation of dimethylamino at the para position of triphenylamine. Cyclic voltammograms of the polyamide films showed their onset potential around 0.38–0.47 V with color changing from nearly colorless to light blue.