Electrochromism Properties of Polyimides Possessing Triphenylamine Moieties with Different Substituents

Abstract

Two diamine monomers with methyl (CH3TPA) and methoxy (OCH3TPA) group substituents in the para position of the triphenylamine (TPA) moiety were synthesized by nucleophilic aromatic substitution using 4-fluoronitrobenzene with p-toluidine and p-anisidine, respectively. From these diamine monomers, electroactive polyimides (PI)s were prepared by the chemical imidization of poly(amic acid) solutions, which were prepared with 4,4 -oxydiphthalic anhydride (ODPA). 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy confirmed that both PIs had been synthesized successfully. The measured inherent viscosity for ODPA-CH3TPA PI and ODPA-OCH3TPA PI was 0.42 and 0.49 dL/g, respectively. The glass transition temperatures for ODPA-CH3TPA PI and ODPA-OCH3PDA PI were 236 • C and 238 • C, respectively, and the thermal degradation temperature of both PIs was above 390 • C. The band gaps of ODPA-CH3PDA and ODPA-OCH3PDA were 3.00 and 2.72 eV, respectively. The oxidation onset potential E ox of ODPA-CH3PDA PI and ODPA-OCH3PDA PI from cyclic voltammetry was 0.73 V and 0.65 V, respectively. The highest occupied molecular orbital and lowest unoccupied molecular orbital values differed according to the groups substituted into the triphenylamine moiety. After applying a voltage, the absorption peak intensity at 723 nm and 752 nm for ODPA-CH3TPA and ODPA-OCH3TPA, respectively, increased. The electrical properties varied according to the chemical structure of synthesized diamines.

Synthesis, characterization and electrochromic properties of polyamides having triphenylamine derivatives

“…A mixture of 5.0 g (13.7 mmol) of DN-p-OCH3TPA, 2.52 g (38.3 mmol) of hydrazine monohydrate, 0.2 g of 10 % Pd-C, and 100 ml of ethanol was stirred at 120°C for 8 h (Scheme 1). The reaction mixture was filtered through Celite to remove the Pd-C, and the filtrate was added to 100 ml of water to obtain precipitates, which were filtered and dried [25,26]. The crude product was recrystallized from ethanol.…”

“…First, 4,4 0 -dinitro-4 00 -methoxytriphenylamine was prepared from p-anisidine (2.5 g, 20.3 mmol), 4-fluoronitrobenzene (6.30 g, 44.6 mmol) and cesium fluoride (6.78 g, 44.6 mmol) dissolved in dried 100 mL DMSO, and stirred at 150°C for 24 h (Scheme 1). The reaction mixture was poured into cold water, resulting in the precipitation of an orange-colored solid, which was collected by filtration and washed with methanol [25,26]. The yield of 4,4 0 -dinitro-4 00 -methyltriphenylamine (DN-p-OCH3TPA) was 5.71 g (70 %); 1 H NMR (DMSO-d 6 In the second step, a diamine monomer was prepared from the reduction of dinitro groups using Pd-C as the reducing agent.…”

Deep-blue emissive and colourless polyimides: optical property tuning by triphenylamino and carbazole chromophores

“…16 Besides thermal robustness, optical transparency is often a required parameter of emissive PI films. 17,18 Some emissive PIs containing TPA subunits 19–21 and featuring electrochromic 22,23 or luminescent 24 properties have been described.…”

Synthesis and properties of electroactive aromatic polyimides with methyl- or trifluoromethyl-protecting triphenylamine units

“…The effect of incorporating the -CH 3 and -CF 3 substituents on the thermal, electrochemical and electrochromic properties of the polyimides will be investigated. Although some polyimides based on 4,4 0 -diamino-4 00methyltriphenylamine have been reported, 56,57 their properties have not been studied systematically yet.…”