Enhanced redox stability and electrochromic properties of aromatic polyamides based on N ,N -bis(4-carboxyphenyl)-N ′,N ′-bis(4-tert -butylphenyl)-1,4-phenylenediamine

Synthesis and characterization of novel donor-acceptor type electrochromic polymers containing diketopyrrolopyrrole as an acceptor and propylenedioxythiophene or indacenodithiophene as a donor

A range of low band gap donor-acceptor conjugated polymers (P1-P3) with backbones composed of diketopyrrolopyrrole (DPP), propylenedioxythiophene (ProDOT) and indacenodithiophene (IDT) units were designed and synthesized using the Stille coupling reaction. The optical, electrochemical and electrochromic properties of the resultant polymers were thoroughly characterized. These polymers showed exceptional solubility in common organic solvents and displayed thermal stability at a high temperature. The optical and electrochemical measurements revealed slight variations in the maximum absorptions and oxidation peaks depending on the intrinsic D-A ratio in each polymer, and narrow band gaps lower than 1.60 eV were found for these polymers. Upon oxidation, the polymer films exhibit distinct color changes (pale violet-red to dark gray for P1, rosy brown to silver for P2, atrovirens to light grey for P3) in the VIS and NIR regions. Moreover, the electrochromic switching studies indicated that these polymers have favorable switching properties, such as rapid response speed and high optical contrast and coloration efficiency, and are outstanding candidates for electrochromic applications.

New fluorinated aromatic polyamides based on N,N-bis(4-carboxyphenyl)-4-trifluoromethylaniline

A new aromatic diacid monomer, N, N-bis(4-carboxyphenyl)-4-trifluoromethylaniline, was synthesized by the substitution reaction of 4-trifluoromethylaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. Several polyamides with 4-trifluoromethyltriphenylamine moieties were prepared from the diacid and various aromatic diamines via the direct phosphorylation polycondensation. All the polyamides were amorphous and readily soluble in many polar organic solvents such as N, N-dimethylacetamide and N-methyl-2-pyrrolidone, and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability with glass transition temperatures of 260–330°C, 10% weight-loss temperatures above 500°C, and char yields higher than 60% at 800°C in nitrogen. These polymers had low dielectric constants of 3.35–3.72 (100 Hz), low water uptake of 1.80–2.60%, and high transparency with an ultraviolet–visible absorption cutoff wavelength in the range of 378–390 nm. Cyclic voltammograms of the polyamide films cast onto an indium-tin oxide–coated glass substrate exhibited a reversible oxidation redox coupled with oxidation half-wave potentials ( E 1/2) of 0.95–1.04 V versus silver/silver chloride in an acetonitrile solution.

Functional Aromatic Polyamides

We describe herein the state of the art following the last 8 years of research into aromatic polyamides, wholly aromatic polyamides or aramids. These polymers belong to the family of high performance materials because of their exceptional thermal and mechanical behavior. Commercially, they have been transformed into fibers mainly for production of advanced composites, paper, and cut and fire protective garments. Huge research efforts have been carried out to take advantage of the mentioned characteristics in advanced fields related to transport applications, optically active materials, electroactive materials, smart materials, or materials with even better mechanical and thermal behavior.

Applications of Tris(4-(thiophen-2-yl)phenyl)amine- and Dithienylpyrrole-based Conjugated Copolymers in High-Contrast Electrochromic Devices

Tris(4-(thiophen-2-yl)phenyl)amine- and dithienylpyrrole-based copolymers (P(TTPA-co-DIT) and P(TTPA-co-BDTA)) were electropolymerized on ITO electrode by applying constant potentials of 1.0, 1.1, and 1.2 V. Spectroelectrochemical investigations revealed that P(TTPA-co-DIT) film displayed more color changes than P(TTPA-co-BDTA) film. The P(TTPA-co-DIT) film is yellow in the neutral state, yellowish-green and green in the intermediate state, and blue (1.2 V) in highly oxidized state. The ∆T_max of the P(TTPA-co-DIT) and P(TTPA-co-BDTA) films were measured as 60.3% at 1042 nm and 47.1% at 1096 nm, respectively, and the maximum coloration efficiency (η) of P(TTPA-co-DIT) and P(TTPA-co-BDTA) films were calculated to be 181.9 cm²·C⁻¹ at 1042 nm and 217.8 cm²·C⁻¹ at 1096 nm, respectively, in an ionic liquid solution. Dual type electrochromic devices (ECDs) consisting of P(TTPA-co-DIT) (or P(TTPA-co-BDTA)) anodic copolymer, ionic liquid-based electrolyte, and poly(3,4-(2,2-diethylpropylenedioxy)thiophene) (PProDOT-Et₂) cathodic polymer were constructed. P(TTPA-co-BDTA)/PProDOT-Et₂ ECD showed high ΔT_max (48.1%) and high coloration efficiency (649.4 cm²·C⁻¹) at 588 nm. Moreover, P(TTPA-co-DIT)/PProDOT-Et₂ and P(TTPA-co-BDTA)/PProDOT-Et₂ ECDs displayed satisfactory optical memory and long term switching stability.

Highly transmissive blue electrochromic polymers based on thieno[3,2-b]thiophene

Polymers based on a thieno[3,2-b]thiophene core modulated by alkylphenyl groups show high optical contrast and deep blue to highly transmissive electrochromic performances.

Synthesis and characterization of novel electrochromic poly(amide-imide)s with N,N′-di(4-methoxyphenyl)-N,N′-diphenyl-p-phenylenediamine units

Novel redox-stable and multi-colored electrochromic poly(amide-imide)s with N,N′-di(4-methoxyphenyl)-N,N′-diphenyl-p-phenylenediamine units were synthesized and characterized.

Tunable electrofluorochromic device from electrochemically controlled complementary fluorescent conjugated polymer films

The fluorescent behavior of the electrofluorochromic devices (Type I) of greenish-yellow emitting P1 and blue emitting P2 can be reversibly switched between the nonfluorescent (oxidized) state and the fluorescent (neutral) state with a superb on/off ratio of 23.8 and 21.9, respectively. Moreover, a tunable electrofluorochromic device (Type II) based on two P1 and P2 polymeric layers that are coated individually on two independent ITO electrodes shows switchable blue-white-(greenish-yellow) multifluorescence states.