Synthesis and electrochromism of novel organosoluble polyarylates bearing triphenylamine moieties

A series of novel aromatic polyarylates with triphenylamine units in the main chain and as the pendent group were prepared from the dicarboxylic acid monomer, N,N‐bis(4‐carboxyphenyl)‐N′, N′‐diphenyl‐1,4‐phenylenediamine (1), and various bisphenols. These polyarylates were amorphous and readily soluble in common organic solvents. They had excellent levels of thermal stability associated with moderately high T_g values (182–263 °C). These polymers exhibited strong UV–vis absorption bands at 357–360 nm in toluene solution and the photoluminescence spectra showed maximum bands around 493–503 nm in the green region. The hole‐transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the polyarylates exhibited two reversible oxidation redox couples in acetonitrile solution at E_onset 0.77–0.79 V and 1.12–1.14 V, respectively. The typical polymer 3b film revealed good stability of electrochromic characteristics, with color change from colorless to green and blue at applied potentials ranging from 0.00 to 1.24 V. These anodically polymeric electrochromic materials not only showed excellent reversible electrochromic stability with good green coloration efficiency (CE = 159 cm²/C) and blue coloration efficiency (CE = 154 cm²/C) but also exhibited high contrast of optical transmittance change (ΔT%), 54% in 895 nm for green color and up to 84% in 595 nm for blue color. After over 100 cyclic switches, the polymer films still exhibited excellent stability of electrochromic characteristics. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2004–2014, 2007     

Soluble blue light emitting pyridine-containing polymers prepared by oxidative-coupling copolymerization

Novel polymers containing pyridine moieties in main chains have been prepared by facile oxidative-coupling co-polymerization of pyridine N-oxide with N-alkyl carbazole and fluorene as the precursor polymers, which were reduced to the pyridine-containing polymers respectively. The polymers were characterized by FT-IR, ¹H NMR, UV-Vis, X-ray, thermo-gravimetric analysis, and fluorescence spectroscopy. The pyridine-containing polymers good solubility in convenient organic solvents, high thermal stability with the onset decomposition temperature above 310 °C. The electrochemical behaviors of the polymers were investigated by cyclic voltammetry; the HOMO and LUMO energy level of the polymers were estimated from the electrochemistry and UV-Vis spectroscopy. The fluorescence spectra of the pyridine-containing polymers display blue light emitting properties in both solution and solid-state film.     

Hexaphenylbenzene end-capped tri(p-phenylenevinylenes): synthesis and properties

Three new hexaphenylbenzene end-capped tri(p-phenylenevinylenes) were synthesized by the Horner–Wadsworth–Emmons reaction in good yields (86–76%). All compounds have bright fluorescent emissions in the blue to blue–green region in solution (λ_max = 445–492 nm in tetrahydrofuran) and also high emission efficiency (Φ_fl = 0.51–0.72 in tetrahydrofuran). They exhibit good electrochemical reversibility, high thermal stability, and have high HOMO value.     

Preparation and characterization of the soluble NLO polyarylates with enhanced electro-optic properties

Three novel nonlinear optical polyarylate polymers were prepared containing one main-chain polymer (mPAR-chr1) and two side-chain polymers (sPAR-chr1, sPAR-chr2) with different kinds of chromophores. The obtained polymers were characterized and evaluated by UV-Vis, ¹H NMR, DSC and TGA. All the polymers exhibited excellent thermal stability, film forming ability and good electro-optic (EO) activity. The relationship between EO coefficients (r ₃₃) and the chromophore concentration of the three polymers had been also characterized and discussed. There were no obvious differences found in EO activity between main-chain and side-chain polyarylates with the same chromophore (chr1). Due to the stronger electron-withdrawing tricyanopyrroline acceptor and the steric effect of the large dendritic groups of chromophore 2 (chr2), polymer sPAR-chr2 showed the largest EO cofficients (64 pm V^?1) in these new polymers.     

Synthesis and properties of N-carbazole end-capped conjugated molecules

A series of novel N-carbazole end-capped π-conjugated molecules were synthesized by a divergent approach with the use of bromination, Suzuki cross-coupling, and Ullmann reactions and their physical properties were investigated. In dilute solution, UV-vis absorption spectra displayed bathochromic shift with respect to their conjugated backbones, and photoluminescence spectra showed emission maxima in the blue region. Thermal analysis revealed that they are thermally stable semi-crystalline and amorphous materials. All molecules exhibited good electrochemical stability with high-lying HOMO energy levels and have potential applications as hole-transporting and light-emitting layers in organic light-emitting diodes or as host materials for electrophosphorescent applications.     

A quick and green ionic liquid-mediated approach for the synthesis of high-performance, organosoluble and thermally stable polyimides

Three diamine monomers with different derivatives of imidazole heterocyclic ring and meta-linked aryl ethers were synthesized and used in polycodensation reaction with various commercial dianhydrides for preparation of a series of novel poly(ether-imide) (PEI)s. The polycodensation reactions were carried out by using conventional method and in a green medium of ionic liquid (IL) without using NMP-pyridine-acetic anhydride. The PEIs were obtained in good yields (80% 96%) with moderate viscosity (0.48 0.66 dL/g) in a shorter reaction time (10 h) in IL as compared with the conventional method (36 h). All of the polymers were amorphous in nature, showed excellent solubility in amide-type polar aprotic solvents with ability to form tough and flexible films, and excellent thermal stability with Tgs in the range of 212 340 ℃ and 10% weight loss temperature (T10) up to 570℃ in N 2 and 528 ℃ in air.     

Electrochromic properties of novel strictly alternating poly(amine-amide-imide)s with electroactive triphenylamine moieties

A series of novel triphenylamine-containing aromatic poly(amine-amide-imide)s (PAAIs) were prepared by the phosphorylation polyamidation reactions from the diamine, N,N′-bis(4-aminophenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various imide ring-preformed dicarboxylic acids. All the PAAIs were amorphous, had good solubility in many polar aprotic solvents, and exhibited excellent thin film forming capability with good mechanical properties. They displayed relatively high glass-transition temperatures (220-306 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 522 °C in air or nitrogen and char yields at 800 °C in nitrogen higher than 66%. The solutions of polymers in NMP exhibited strong UV-vis absorption bands with a maximum around 315 nm. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the PAAIs prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at 0.63 and 1.01 V vs. Ag/AgCl in acetonitrile solution. All the PAAIs revealed very stable electrochromic characteristics, changing color from original pale brownish to green, and then to blue at 0.67 and 1.08 V, respectively.     

Synthesis and electro-optical features of a high T g polymer system with excellent electro-optic activity and thermal stability

Three chromophores with tricyanofuran and tricyanopyrroline electron acceptors were synthesized and doped in high glass transition temperature (T _g) polymer poly(N-(4-acetoxylphenyl)maleimide-co-styrene, NAPMI-co-ST). The electro-optic (EO), optical, and thermal properties of the doped poly(NAPMI-co-ST) were characterized and discussed. After being corona poled under 12?kV, this high T _g polymer material showed excellent EO activity and thermal stability. The highest EO coefficient (r ₃₃) reached 48.2?pm?V^?1 (1,310?nm) and could remain 90?% of the original value for 100?h at 85?°C. The EO coefficient was relatively higher compared with other high T _g EO polymers. The thermal stability was also very good and the manufacture process was convenient and applicable for device fabrication.     

Efficient blue lighting materials based on truxene-cored anthracene derivatives for electroluminescent devices

A new series of anthracene derivatives containing a truxene moiety as the core have been synthesized and characterized. They emit in the blue region with excellent solution fluorescence quantum yields and possess high thermal decomposition temperature (T_d>458 °C). Typical electroluminescence performance was demonstrated by 2-[10-(4-(1-napthenyl)phenyl)anthracene-9-yl]-5,5′,10,10′,15,15′-hexaethyltruxene (NPAT) as the blue lighting material in the OLED with structure of ITO/CFx/NPAT/TPBI or Alq₃/LiF/Al, where TPBI and Alq₃ are 1,3,5-tri(N-phenylbenzimidazol-2-yl)-benzene and tris(8-hydroxyquinolinato)aluminum, respectively. Additionally, the effects of the different thickness of the different electron transporting layers on the device performance were investigated.     

Novel cardo-type heat-resistant polyimides bearing 9H-xanthene and polymer-based nanocomposite consisting of NH2-terminated TiO2: Synthetic strategies,extraction of methylene blue dye,and biological activities

In the present study, a series of cardo-type novel polyimides (PI)s containing xanthene groups was synthesized. All the polymers were amorphous in nature with inherent viscosities in the range of 0.72–0.91 dl/g. Study of thermal behavior showed that PIs have excellent thermal stability with 10% weight loss at temperatures (T_d10%) between 426 and 528 °C, glass transition-related temperatures (T_g) in the range of 292–305 °C, and weight residual at 700 °C ranged from 55% to 68% under N₂ atmosphere. Xanthene and fluorene presence, progressed the PIs solubility and also induced good biological activities. The in vitro anticancer activity of the 6FD-derived PI against the A431 (epidermoid carcinoma) cells showed an IC₅₀ value of 29.3 μM. In the next part of the work, a polymer-based composite (PI-B/m-TiO₂@HBP) was prepared by inscribing 20 wt% of hyperbranched polyamide-grafted TiO₂ nanoparticles into BTDA-derived PI-B matrix, and compared with the unfilled PI, its photoluminescence intensity and thermal stability properties were increased. The PI-B and nanocomposite exhibited good antibacterial activity against six bacterial strains. In the following, study of methylene blue (MB) dye adsorption from aqueous solution by the obtained PIs and PI-B/HBP@TiO₂ was carried out and removal efficiency values were found above 80.62%.     

三芴及螺旋三芴等衍生物的吸收和发光性质的理论研究

The structures, ionization potentials （IP）, electron affinities （EA） and HOMO-LUMO gaps （AEH.L） of the terfluorene oligomers were studied by the density functional theory with B3LYP functional. The characters of the front orbitals were analyzed on the basis of the ground structure. The vertical excitation energies Ev and the maximal absorption wavelengths λabs of a series of ter（9,9-diarylfluorene） compounds were studied employing the time dependent density functional theory （TD-DFT） and ZINDO. The calculated maximal absorption wavelengths by both methods are in good agreement with the experimental data. The results show that the differences between terfluorene hh and ter（9,9-diarylfluorene） derivatives are slight in the structures and the electronic states except that there is the spiroconjugation in the latter. The spiroconjugation made these derivatives far from optimization in terms of stability. Excited structure of hh was calculated to be compared with the ground structure, which indicats that it has strong coplanar tendency of aromatic ring with the neighbour in the excited state. Consequently, they are good blue emitting materials with promising thermal stability.     

Electrochemical and electrochromic properties of novel aromatic poly(amine-amide)s derived from N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine

A series of novel triphenylamine-containing aromatic poly(amine-amide)s were prepared from the dicarboxylic acid, N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine-amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195-280 °C). These polymers exhibited strong UV-Vis absorption bands at 330-346 nm and their photoluminescence showed maximum bands around 516-535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide)s prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73-0.78 V and 1.12-1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine-amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms.     

A novel donor–acceptor molecule containing a cyclic triphenylamine dimer: synthesis,characterization, and application in memory device

A novel highly soluble push–pull molecule containing electron-rich cyclic triphenylamine dimer (TPAD) and electron-poor N-phenyl-N′-octyl-naphthalene-1,4,5,8-tetracarboxylic acid bisimide [NI-(8,PBr)] was synthesized under Suzuki-coupling conditions. The resulting compound exhibited excellent thermal stability (T_d=354.3 °C) and good solubility in common organic solvents. Cyclic voltammogram and optical absorption spectroscopy showed that both the electroactive units preserve their nature, respectively, in the ground state, whereas photophysical investigations showed a strong fluorescence quenching. Interestingly, excellent switching behavior with extremely high ON/OFF current ratio (1.6E8 at +1 V) was observed through memory devices based on thin films of this material.     

Synthesis, characterization, photophysical and electrochemical properties of new phosphorescent dopants for OLEDs

New heteroleptic iridium(III) complexes of 2-(p-substituted-phenyl)-pyridine were synthesized and characterized. These complexes have two cyclometalated ligands (C^∧N) and a bidentate ancillary ligand (LX), that is, (C^∧N)₂Ir(LX). LX was either acetylacetonate or 5-nitro-8-hydroxy quinolate. Substitution on the p-phenyl of C^∧N ligands was used to alter the electronic properties of these complexes. The (C^∧N)₂Ir(acac) complexes show phosphorescence with good quantum yields and microsecond lifetimes and also show photoluminescence over a wide visible range (λ_max = 503-620 nm). The HOMO level and triplet energy level of these complexes were also determined. These data indicate their potential use as emitting materials for organic light emitting diodes, OLEDs.     

Novel blue light-emitting hyperbranched polyfluorenes incorporating carbazole kinked structure

A novel series of soluble hyperbranched polyfluorenes P1−P6 with various branching degrees and contents of kinked carbazole units were successfully synthesized with good yields and high molecular weight via a facile “A2 + B2 + C3 + D2” approach. The thermal, optical, and electrochemical properties as well as thermal spectral stability of the resulting hypberbranched polymers were investigated. All polymers exhibited good thermal stabilities and bright blue emission in both solutions and solid-states. Hyperbranched polyfluorenes (P3 and P6) exhibited improved spectral stability upon annealing at 200 °C in air, in sharp contrast to the linear poly(9,9-dihexylfluorene) (PDHF) that showed significant additional green emission at ca. 530 nm within minutes. In particular, outstanding spectral stability was observed with carbazole-incorporating hyperbranched polyfluorene P6. Electrochemical characterization indicated that the presence of carbazole also effectively raised the HOMO level with respect to that of polyfluorene homopolymer, suggesting better hole-injection properties. Hence, the incorporation of kinked carbazole unit into hyperbranched polyfluorenes could provide a new methodology for preparing blue light-emitting polymers with improved optoelectronic characteristics.     

Synthesis and characterization of new soluble and thermally stable aromatic poly(amide-imide)s based on N-[3,5-bis(N-trimellitoyl)phenyl]phthalimide

A new dicarboxylic acid, N-[3,5-bis(N-trimellitoyl)phenyl]phthalimide (1a), bearing three preformed imide rings was synthesized from the condensation of N-(3,5-diaminophenyl)phthalimide and trimellitic anhydride in glacial acetic acid at 1:2 molar ratio. For study of structure-properties relationship 1,3-bis(N-trimellitoyl)benzene (1b, as a reference) was also synthesized in a similar manner. 1a and 1b were characterized by spectroscopic methods and elemental analyses.A series of wholly aromatic poly(amide-imide)s with inherent viscosities of 0.63-1.09 dl g⁻¹ was prepared by triphenyl phosphite-activated polycondensation from the triimide-dicarboxylic acid 1a and the reference monomer 1b with various aromatic diamines. All of the polymers were fully characterized by FT-IR and ¹H NMR spectroscopy. The effects of the phthalimide pendent group on the polymers properties such as solubility, crystallinity, and thermal stability were investigated by comparison of the polymers. The polymers obtained from triimide-dicarboxylic acid 1a exhibited excellent solubility in a variety of solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethylsulfoxide. These poly(amide-imide)s possessed glass-transition temperatures from 334 to 403 °C and exhibited excellent thermal stabilities and had 10% weight losses from 541 to 568 °C under a nitrogen atmosphere. Poly(amide-imide)s containing phthalimide pendent groups showed higher solubility, higher T_g and T_d10% values than those having no phthalimide pendent groups.     

New ladder‐type conjugated polymer containing carbazole and fluorene units in backbone: Synthesis,optical, and electrochemistry properties

This article describes the synthesis and characterization of a new ladder‐type poly (p‐phenylene) (LPFC) containing alkylcarbazole and dialkylfluorene units in backbone, and its optical and electrochemical properties as well as its light‐emitting device performance. LPFC shows the well‐defined structure, high molecular weights, excellent thermal stability, and good solubility in common organic solvents. And it also shows strongly blue emission (λ_max = 465 nm) with quantum efficiency of 70% in solution, while its solid emission (λ_max = 470 nm) is almost the same as its solution. Electrochemical studies show that the highest occupied molecular orbital (HOMO) energy levels of LPFC is up to 5.29 eV, which is significantly higher than that of LPPP without carbazole in backbone, indicating an enhanced ability of hole injection from anodes. Furthermore, the single layer light‐emitting device using LPFC as the active layer shows blue emission (λ_max = 470 nm) with maximum luminescence of ～ 2000 cd/m² and maximum luminance efficiency of 0.43 cd/A. The attractive properties exhibited from new ladder‐type polymer establish LPFC as a good candidate for the potential application as transporting and emitting layer in polymeric light emitting diodes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3120–3127, 2008     

Gas transport properties of polyarylates part II: Tetrabromination of the bisphenol

The gas transport properties of a series of polyarylates based on isophthalic acid have been examined. The polyarylates were synthesized from the following bisphenol monomers with and without tetrabromo substitution: bisphenol A, hexafluorobisphenol A, phenolphthalein, and fluorene bisphenol, to study the effects of tetrabromination in combination with varying the bisphenol connector group size and shape. Substitution of a tertiary butyl group at position five on the isophthalate ring was used to increase polymer permeability. Tetrabromination of the bisphenol maintains or increases gas permeability and significantly increases permselectivity particularly for the O₂/N₂ gas pair as compared with the non-brominated analog. The substitution of t-butyl groups increases gas permeability by two-to fourfold but lowers permselectivity. Most of the increase in permeability can be related to an increase in the diffusion coefficient for each gas. All the brominated polyarylates have gas transport properties superior to most known glassy materials for O₂/N₂ separation with several materials close to a proposed empirical “upper bound” between permeability and selectivity. © 1995 John Wiley & Sons, Inc.     

Free-standing anion-exchange PEO–SiO2 hybrid membranes

Free-standing anion-exchange polyethylene oxide (PEO)–SiO₂ hybrid membranes with higher flexibility and good mechanical strength (tensile strength (TS) as high as 20.55 MPa) as well as high temperature tolerance (thermal degradation temperature in air, T_d, in the range of 220–240 °C) were prepared through sol–gel reaction of different precursors: charged alkoxysilane-functionalized PEO-1000 (PEO-[Si(OCH₃)₃]₂(+)), N-triethoxysilylpropyl-N,N,N-trimethylammonium iodine (A-1100(+)), monophenyltriethoxysilane (EPh) and in some cases also tetraethoxysilane (TEOS). Properties of the hybrid membranes, such as the thermal stability, tensile properties, hydrophilicity, and electrical performances, can be controlled by changing the feed ratio of the different sol–gel precursors. The results showed that some of the membranes have relatively good conductivity (∼0.003 S/cm) and so may find potential applications in alkaline membrane fuel cells.     

Novel aromatic polyimides derived from benzofuro[2,3-b]benzofuran-2,3,8,9-tetracarboxylic dianhydride (BBTDA)

Benzofuro[2,3-b]benzofuran-2,3,8,9-tetracarboxylic dianhydride (BBTDA) is introduced as a monomer for the synthesis of a series of novel polyimides with enhanced high thermal stability. Polyimides derived from BBTDA and aromatic diamines showed high glass transition (T_g>296 °C) and degradation (T₅>455 °C) temperatures, and were soluble in organic solvents (i.e. N-methyl pyrrolidone (NMP), N,N^′-dimethylformamide (DMF), N,N^′-dimethylacetamide (DMAc)). The polymerization yielded high-molecular-weight polyimides with inherent viscosities ranging from 1.75 to 2.14 dl/g. The polymers were characterized by IR and elemental analysis.