Hyperbranched framework of interrupted π‐conjugated polymers end‐capped with high carrier‐mobility moieties for stable light‐emitting materials with low driving voltage

A novel series of soluble hyperbranched interrupted π‐conjugated polymers (HICPs) based on complicated 9,9‐diarylfluorenes (CDAFs) branching core and end‐capped with high carrier‐mobility pyrene moieties were synthesized via the “A₂ + A′₂ + B₃” type Suzuki coupling condensation. The new polymer architecture improves the spectrum stability than the corresponding linear and hyperbranched polymers in PLEDs. Besides, it overcomes the drawback of high driving voltage of common interrupted π‐conjugated polymers. CDAF1 exhibits excellent thermal and morphological stability with a decomposition temperature (T_d) higher than 445 °C and a glass transition temperature (T_g) up to 128 °C. No obvious low‐energy green emission band at 520 nm was observed under extreme thermal annealing conditions in air at 200 °C for 12 h. The CDAF1 device shows stable blue emission with the peak at 422 and 447 nm. The Commission International d'Eclairage (CIE) 1931 coordinates is (0.18, 0.16) and the brightness reaches 1051 cd/m² at 15.7 V. White PLED based on CDAF1/MEH‐PPV blends exhibits a low turn‐on voltage of 4.8 V with voltage‐independent CIE of (0.32, 0.32). Molecular simulations were used to investigate the conformation and interchain interaction. HICPs based on CDAFs tethered with high‐mobility moieties are promising stable blue and host materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6451–6462, 2009     

Synthesis and electroluminescent properties of polyfluorene‐based conjugated polymers containing bipolar groups

A bipolar dibromo monomer, bis‐(4‐bromophenyl)[4‐(3,5‐diphenyl‐1,2,4‐ triazole‐4‐yl)‐phenyl]amine ( 9 ), containing electro‐rich triphenylamine and electro‐deficient 1,2,4‐triazole moieties was newly synthesized and characterized. Two fluorescent fluorene‐based conjugated copolymers ( TPAF , TPABTF ) were prepared via facile Suzuki coupling from the dibromo bipolar monomer, 4,7‐dibromo‐2,1,3‐benzothiadiazole ( BTDZ ), and 9,9‐dioctylfluorene. They were characterized by molecular weight determination, IR, NMR, DSC, TGA, solubility, absorption and photoluminescence spectra, and cyclic voltammetry. The polymers showed good solubility in common organic solvents such as dichloromethane, chloroform, tetrahydrofuran, and dichlorobenzene at room temperature. They had glass transition temperatures (T_g) higher than 135 °C and 5% degradation temperatures in nitrogen atmosphere were higher than 428 °C. Single layer polymer light‐emitting diodes (PLED) of ITO/PEDOT:PSS/polymer/metal showed a blue emission at 444 nm and Commission Internationale de I'Eclairage (CIE) 1931 color coordinates of (0.16, 0.13) for TPAF . The device using TPABTF as emissive material showed electroluminescence at 542 nm with CIE1931 of (0.345, 0.625), low turn‐on voltage of 5 V, a maximum electroluminance of 696 cd/m², and a peak efficiency of 2.02 cd/A. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6231–6245, 2009     

Synthesis and optoelectronic properties of alternating benzofuran/terfluorene copolymer with stable blue emission

The solution processable alternating benzofuran/terfluorene copolymer bearing side oxadiazole groups ( PBF‐OXD ) was synthesized and its optoelectronic properties and color stability were investigated. Electron‐deficient and stereohindered oxadiazole units were used as pendent groups to compensate for the poor electron‐transporting ability of a p‐type polymer backbone, to depress the intermolecular π‐stacking, and to improve solubility while retaining polymer blue emission. PBF‐OXD showed a glass transition at 135 °C and an onset decomposition temperature of ～345 °C. A simple EL device, with the configuration of ITO/PEDOT:PSS/ PBF‐OXD /Ba/Al, displayed a stable blue emission (λ_max = 434 nm), good color purity (full width half‐maximum = 59 nm), maximum brightness of 1400 cd/m², and a maximum luminance efficiency of 0.95 cd/A. The PL and EL spectra changed slightly on annealing and on increasing the applied voltage. These results show that the as‐synthesized copolymer PBF‐OXD had integrated respective functions of its different building blocks and exhibited good thermal and color stability with improved EL performance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5488–5497, 2009     

Electrochromic material containing unsymmetrical substituted N,N,N′,N′‐tetraaryl‐1,4‐phenylenediamine: Synthesis and their optical,electrochemical, and electrochromic properties

A novel dibromo compound containing unsymmetrical substituted bi‐triarylamine was synthesized. A conjugated polymer was prepared via the Suzuki coupling from the newly prepared dibromo compound and 9,9‐dioctylfluorene‐2,7‐bis(trimethyleneboronate). The glass transition temperature (T_g) of the conjugated polymer was 140 °C, 10% weight‐loss temperatures (T_d10) in nitrogen was 458 °C, and char yield at 800 °C in nitrogen higher than 64%. Cyclic voltammogram of the polymer film cast onto an indium‐tin oxide (ITO)‐coated glass substrate exhibited two reversible oxidation redox couples at 0.70 and 1.10 V versus Ag/Ag⁺ in acetonitrile solution. The polymer films revealed excellent stability of electrochromic characteristics, with a color change from yellow green of the neutral form to the dark green and blue of oxidized forms at applied potentials ranging from 0 to 1.3 V. The color switching time and bleaching time were 4.25 and 7.22 s for 860 nm and 5.51 s and 6.48 s for 560 nm. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1469–1476, 2010     

A wide band gap polymer derived from 3,6‐carbazole and tetraphenylsilane as host for green and blue phosphorescent complexes

We have synthesized a novel wide band gap polymer P36HCTPSi derived from 3,6‐carbazole and tetraphenylsilane by palladium‐catalyzed Suzuki coupling reaction. The resultant polymer shows a high glass transition temperature (217 °C) and good thermal stability. The conjugation length of P36HCTPSi is effectively confined because of the δ‐Si interrupted polymer backbone. The polymer exhibits a violet emission with a peak at 392 nm in solution, and the band gap estimated from the onset of its absorption is 3.26 eV. The high energy emission and wide band gap of P36HCTPSi make it appropriate host for green and blue emission phosphorescent materials. Efficient energy transfers from P36HCTPSi to both fac‐tris[2‐(2‐pyridyl‐kN)‐5‐methylphenyl]iridium(III) (green emission) and bis[(4,6‐difluorophenyl)pyridinato‐N,C²]‐(picolinato)iridium(III) (blue emission) were observed in photoluminescence (PL) spectra. Highly efficient phosphorescent polymer light‐emitting devices were realized by using P36HCTPSi as the host for iridium complexes, the maximum luminous efficiencies for green and blue devices were 27.6 and 3.4 cd/A, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4784–4792, 2009     

Synthesis and characterization of 9,10‐diphenylanthracene‐based blue light emitting materials

A new series of conjugated polymers having diphenylanthracene vinylene biphenylene and diphenylanthracene vinylene terphenylene in the main chain and fluorene pendant group, were synthesized by nickel catalized Yamamoto coupling and palladium catalized Suzuki coupling. The obtained polymers showed good solubility in the common organic solvent and number average molecular weights of 14,000–9500 with a polydispersity indexes ranging from 1.7 to 2.1. Both polymers possess excellent thermal stability with glass transition temperatures of 123–127 °C and the onset decomposition temperatures of 420–400 °C. The obtained polymers showed blue emission (λ_max = 461 for PFPA and λ_max = 455 nm for PFPAME) in PL spectra, specially, PFPAME containing diphenylanthracene vinylene terphenylenevinylene showed the consistent emission in the solution and film. The double‐layered device with an ITO/PEDOT/PFPAME/LiF/Al structure has a turn‐on voltage of about 5.8 V, maximum brightness of 152 cd/m² and an electroluminescent efficiency of 0.143 lm/W, and stable blue EL emission that is not altered by increased voltage. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5908–5916, 2009     

One‐step synthesis of a thienylenepyridazinylenethienylene‐based coil‐rod‐coil copolymer with enhanced emission and improved fluorescence stability

A new coil‐rod‐coil copolymer is synthesized via Sonogashira coupling using one‐step methodology. The copolymer PEG‐OEPETPT‐PEG constitutes of poly(ethylene glycol) (PEG) as the coil block, and oligo[p‐(ethynylenephenyleneethynylene)‐alt‐(thienylenepyridazinylenethienylene)] (OEPETPT) as the rod segment. The conjugated polymer PEPETPT with the same conjugated building blocks is also synthesized for comparison. The structures of both polymers are confirmed by NMR, combined with other characterizations. PEG‐OEPETPT‐PEG has a 12 nm blue‐shift in the emission maximum compared with that of PEPETPT, and a higher quantum yield of fluorescence in THF. PEG‐OEPETPTE‐PEG tolerates up to 20% water content in H₂O/THF mixed solvent without significantly changing the emission wavelength and intensity, while the fluorescence of PEPETPT is dramatically quenched by a very small quantity of water. Further photophysical studies about these two polymers indicate that the introduction of PEG coils onto the conjugated block retards the water‐induced‐aggregation and therefore improves the fluorescence stability of PEG‐OEPETPT‐PEG. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of an ionic conjugated polymer: Poly[2‐ethynyl‐N‐(2‐thiophenecarbonyl) pyridinium chloride]

The activated polymerization of 2‐ethynylpyridine by using 2‐thiophenecarbonyl chloride yielded the corresponding conjugated ionic polymer, poly[2‐ethynyl‐N‐(2‐thiophenecarbonyl)pyridinium chloride] (PETCPC). The polymerization proceeded well to give high yield of polymer without any additional initiator or catalyst. The instrumental analysis data on polymer structure indicated that the present ionic polymer have a conjugated polymer backbone system having N‐(2‐thiophenecarbonyl)pyridinium chloride as substituents. The photoluminescence maximum peak of PETCPC was located at 573 nm, which corresponds to the photon energy of 2.16 eV. The aromatic functional substituents in the conjugated backbone system shift PL maximum values because it makes different molecule arrangement. The cyclovoltamograms of PETCPC exhibited the electrochemically stable window at ?1.24 to 1.80 V region. It was found that the kinetics of the redox process of polymer might be controlled by the reactant diffusion process from the experiment of the oxidation current density of polymer versus the scan rate. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6153–6162, 2009     

Photophysical and electrochemical characterization of new poly(arylene vinylene) copolymers containing quinoline or bisquinoline segments

Four new fluorescent conjugated vinylene‐copolymers incorporating quinoline or bisquinoline segments along the backbone were synthesized by Heck coupling. Three of them were fluorenevinylene‐copolymers and contained quinoline ( PQFV , PQFVT ) or bisquinoline segments ( PBQFV ). One of them ( PBQPV ) was phenylenevinylene‐copolymer and contained bisquinoline segments. All the copolymers were soluble in common organic solvents and had relatively low glass transition temperature (T_g = 50–56 °C for fluorenevinylenes and T_g < 25 °C for phenylenevinylene). In THF solutions, the quinoline‐containing copolymers showed absorption maxima at 411–420 nm while the bisquinoline‐containing ones exhibited maxima at 357–361 nm. The emission maxima of solutions were 465–490 nm. The copolymers showed high quantum yields up to 64%. The films exhibited absorption and emission maxima in the range of 371–437 nm and 480–521 nm, respectively. All copolymers revealed reversible reduction with electron affinity of 2.66–3.53 eV and irreversible oxidation scans with ionization potential of 5.39–5.53 eV. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3370–3379, 2009     

Synthesis and characterization of indeno[1,2‐b]fluorene‐based white light‐emitting copolymer

An indenofluorene‐based copolymer containing blue‐, green‐, and red light‐emitting moieties was synthesized by Suzuki polymerization and examined for application in white organic light‐emitting diodes (WOLEDs). Tetraoctylindenofluorene (IF), 2,1,3‐benzothiadiazole (BT), and 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (DBT) derivatives were used as the blue‐, green‐, and red‐light emitting structures, respectively. The number‐average molecular weight of the polymer was determined to be 25,900 g/mol with a polydispersity index of 2.02. The polymer was thermally stable (T_d = ～398 °C) and quite soluble in common organic solvents, forming an optical‐quality film by spin casting. The EL characteristics were fine‐tuned from the single copolymer through incomplete fluorescence energy transfer by adjusting the composition of the red/green/blue units in the copolymer. The EL device using the indenofluorene‐based copolymer containing 0.01 mol % BT and 0.02 mol % DBT units ( PIF‐BT01‐DBT02 ) showed a maximum brightness of 4088 cd/m² at 8 V and a maximum current efficiency of 0.36 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.34, 0.32). The EL emission of PIF‐BT01‐DBT02 was stable with respect to changes in voltage. The color emitted was dependent on the thickness of the active polymer layer; layer (～60 nm) too thin was unsuitable for realizing WOLED via energy transfer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3467–3479, 2009     

An X‐shaped π‐conjugated polymer comprising of fluorene units and anthracene units with high efficiency. Synthesis and optical and electrochemical properties

A new X‐shaped π‐conjugated monomer comprising of fluorene units and anthracene units was synthesized, and it was used to fabricate the new X‐shaped π‐conjugated polymers and investigate the properties of the new polymers. Using different molar ratios between such monomer and a fluorene monomer gave three polymers that showed higher absolute PL quantum yields than the linear polyfluorene (PF) in the solid state. After thermal annealing at 200 °C for 4 h, the linear PF showed an additional bathochromic emission at about 550 nm, whereas such red‐shifted emission was fully eliminated for the X‐shaped polymers. The electroluminescent devices based on the X‐shaped polymers with a configuration of ITO/PEDOT:PSS/polymer/LiF/Ca/Al displayed blue emission with low turn‐on voltage and high brightness. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5616–5625, 2008     

High‐efficiency blue light‐emitting polymers based on 3,6‐silafluorene and 2,7‐silafluorene

A novel blue‐emitting polymer based on 3,6‐silafluorene and 2,7‐silafluorene was synthesized via the Suzuki polycondensation. The resulting polymers are readily soluble in common organic solvents, such as toluene, xylene, THF, and chloroform. The thermal, electrochemical, photophysical, and electroluminescence properties of the resulting polymers were investigated. The device fabricated from the copolymer with a configuration of ITO/PEDOT:PSS/PVK/polymer/Ba/Al exhibited an external quantum efficiency of 1.95%, a luminous efficiency of 1.69 cd A^?1 and a maximal brightness of 6000 cd m^?2. It has been found that the incorporation of the 3,6‐silafluorene unit into the poly(2,7‐silafluorene) main chain can not only improve the color purity of the devices from the resulting copolymer but also enhance its device efficiency. Moreover, no undesired long‐wavelength green emission was observed in the PL spectra of P36‐27SiF90 compared to that of PFO with a dominating emission at 500–600 nm after thermal annealing at 200 °C for 8 h. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4941–4949, 2007     

Synthesis and characterization of a new ethynyl‐linked alternating anthracene/fluorene copolymer for organic thin film transistor

A new p‐type conjugated copolymer, poly(9,10‐diethynylanthracene‐alt‐9,9‐didodecylfluorene) (PDADF), which is composed of ethynyl‐linked alternating anthracene/fluorene, is synthesized via a palladium(II)‐catalyzed Sonogashira coupling reaction with 9,10‐diethynylanthracene and 2,7‐diiodo‐9,9‐didodecyl‐fluorene. The obtained polymer is confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is ?5.62 eV as measured via cyclic voltammetry (CV). A solution‐processed thin film transistor device showed a carrier mobility value of 6.0 × 10^?4 cm²/Vs with a threshold voltage of ?17 V and a capacitance (C_i) of 10 nF/cm². The out‐of‐plane and in‐plane GIXD pattern of spin‐coated polymer on SiO₂ dielectric surfaces showed an amorphous halo near 2θ = 20°. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1609–1616, 2009     

Synthesis and optical properties of novel blue‐light‐emitting poly(p‐phenylene vinylene) derivatives with pendant oxadiazole or cyano groups

Two novel poly(p‐phenylene vinylene) polymers, which carried side substituents with cyano groups or 1,3,4‐oxadiazole, were synthesized by Heck coupling. They consisted of alternating conjugated segments and nonconjugated aliphatic spacers. The polymers had moderate molecular weights, were amorphous, and dissolved readily in tetrahydrofuran and halogenated organic solvents. They were stable up to approximately 340 °C in N₂ and 290 °C in air, and the anaerobic char yield was around 60% at 800 °C. The polymer with cyano side groups emitted blue light in solutions and thin films with identical photoluminescence (PL) maximum at 450 nm; this supported the idea that chain interactions were hindered even in the solid state. The PL maximum of this polymer in thin films was blueshifted upon annealing at 120 °C, indicating a thermochromic effect as a result of conformational changes in the polymer backbone. The polymer containing side substituents with oxadiazole rings emitted blue light in solutions with a PL maximum at 474 nm and blue‐greenish light in thin films with a PL maximum at 511 nm. The PL quantum yields of the polymers in tetrahydrofuran were 0.13–0.24. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1768–1778, 2004     

Synthesis and properties of conjugated polymers containing 3,9‐ and 2,9‐linked carbazole units in the main chain

Novel conjugated polymers containing 3,9‐ or 2,9‐linked carbazole units in the main chain were synthesized by the polycondensation of ethynyl‐ and iodo‐substituted 9‐arylenecarbazolylene monomers, and their optical and electrical properties were studied. Polymers with weight‐average molecular weights of 3400–12,000 were obtained in 76–99% yields by the Sonogashira coupling polycondensation in piperidine or tetrahydrofuran (THF)/piperidine at 30 °C for 48 h. All the 3,9‐linked polymers absorbed light around 300 nm. The para‐phenylene‐linked polymer also absorbed light around 350 nm, while meta‐phenylene‐linked one did not. The 3,9‐linked polymers absorbed light at a wavelength longer than the 2,9‐linked one. The polymers emitted blue fluorescence with high quantum yields (0.21–0.78) upon excitation at the absorption maxima. The polymers were oxidized around 0.6 V, and reduced around 0.5 V. Poly( 1 ) showed the dark conductivity of 3.7 × 10^?11 S/cm (10³ V/cm). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3506–3517, 2009     

Synthesis of through‐space conjugated polymers containing [2.2]paracyclophane and thieno[3,4‐b]pyrazine in the main chain

We synthesized through‐space conjugated polymers with [2.2]paracyclophane and thieno[3,4‐b]pyrazine units in the main chain by the Sonogashira–Hagihara coupling reaction. The obtained polymers were soluble in common organic solvents, and homogeneous thin films were readily obtained from the polymer solutions by spin‐coating techniques. The polymers exhibited the extension of the conjugation length via the through‐space interaction. The polymers showed orangish‐red emission with peak maxima of around 610 nm in diluted solutions and their thin films, which were derived from the thieno[3,4‐b]pyrazine moieties. The optical and electrochemical behaviors of the polymers containing pseudo‐para‐ and pseudo‐ortho‐linked [2.2]paracyclophane were identical. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Synthesis and characterization of color‐stable electroluminescent polymers: Poly(dinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene)s

Two new stepladder conjugated polymers, that is, poly(7,7,15,15‐tetraoctyldinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene) (PONSI) and poly(7,7,15,15‐tetra(4‐octylphenyl)dinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene) (PANSI) with alkyl and aryl substituents, respectively, have been synthesized and characterized. In comparison with poly(indenofluorene)s, both polymers have extended conjugation at the direction perpendicular to the polymer backbone because of the introduction of naphthalene moieties. The emission color of the polymers in film state is strongly dependent on the substituents. While PONSI emits at a maximum of 463 nm, PANSI with the same backbone but aryl substituents displays dramatically redshifted emission with a maximum at 494 nm. Both polymers show stable photoluminescence spectra while annealing at 200 °C in inert atmosphere. The PONSI‐based devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al turn on at 3.7 V, and emit at a maximum of 461 nm with the CIE coordinates of (0.19, 0.26), a maximum luminance efficiency of 1.40 cd/A, and a maximum brightness of 2036 cd/m² at 13 V. Meanwhile, the emission color of the devices is independent of driving voltage and keeps unchanged during the continuous operation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4866–4878, 2008     

Synthesis,optical properties,and electroluminescence of conjugated poly(p‐phenylenevinylene) derivatives containing 1,3,4‐oxadiazole and pyridine rings in the main chain

Three new poly(p‐phenylenevinylene) derivatives—PO, POD, and POP—with oxadiazole and pyridine rings along the main chain were synthesized via Heck coupling. The polymers were amorphous and dissolved readily in common organic solvents. They showed relatively low glass‐transition temperatures (up to 42 °C) and satisfactory thermal stability. Solutions of the polymers emitted blue‐greenish light with photoluminescence (PL) emission maxima around 460 nm and PL quantum yields of 0.28–0.49. Thin films of the polymers displayed PL emission maxima at 461–521 nm, and their tendency to form aggregates was significantly influenced by the chemical structure. Light‐emitting diodes with polymers PO and POP, with an indium tin oxide/poly(ethylenedioxythiophene) (PEDOT)/polymer/Ca configuration, emitted yellow and green light, respectively, and this could be attributed to excimer emission. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3212–3223, 2004     

Polyfluorenes containing tetraphenylthiophene segments: Synthesis,photophysics, and electroluminescence

2,5‐Bis(4‐bromophenyl)‐3,4‐diphenylthiophene was synthesized from benzyl chloride and sulfur and through the subsequent bromination of the intermediate 2,3,4,5‐tetraphenylthiophene. It was condensed with 2,7‐dibromo‐9,9‐dihexylfluorene via a nickel‐mediated Yamamoto coupling reaction to afford a new series of statistical copolymers with various compositions. In addition, poly(9,9‐dihexylfluorene) (PF) was synthesized under the same conditions for comparison. All the polymers were soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, and dichloromethane. Their glass‐transition temperatures increased with an increase in the tetraphenylthiophene (TPT) content in the polymers, and they were 63–149 °C. The solutions of the polymers in THF emitted intense blue light with a photoluminescence maximum at 418–440 nm and quantum yields of 0.32–0.62. Thin films of the polymers with TPT fractions lower than 20 mol % emitted blue‐green light with two well‐resolved peaks at 445 and 520 nm and an optical band gap of about 2.85 eV. A thin film of the polymer with aTPT fraction of 50 mol % emitted pure blue light with a maximum at 419 nm and an optical band gap of 3.28 eV. An enhancement of the light‐emitting‐diode brightness by a factor of ～8 with respect to that of PF was achieved in apolymer containing 5 mol % TPT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4015–4026, 2006     

Hyperbranched copolymer containing triphenylamine and divinyl bipyridyl units for fluorescent chemosensors

A fluorescent hyperbranched copolymer (HTP) and a linear copolymer (PTP) as a reference sample to HTP both containing triphenylamine and divinyl bipyridyl units were synthesized via Heck coupling reaction from 5,5′‐Divinyl‐2,2′‐bipyridyl with tris(4‐bromophenyl)amine and with 4,4′‐dibromotriphenylamie, respectively. The chemical structure of HTP was confirmed by FTIR, ¹H NMR, and ¹³C NMR. The polymer HTP had a number‐average molecular weight of 1895 and a weight‐average molecular weight of 2315, and good solubility in conventional organic solvents, such as THF, DMF, and chloroform, and exhibited good thermal stability. The UV–vis absorption and photoluminescence (PL) spectra exhibited absorption maximum at 428 nm and emissive maximum at 531 nm for the HTP solution. The spectroscopic results of HTP and PTP indicated that hyperbranched conjugated structure increases the effective conjugation length, as compared with corresponding linear conjugated structure. The fluorescence of the polymer in solution can be quenched by various transition metal ions. The effect of backbone structure of the conjugated polymer‐based chemosensors on the sensitivity and selectivity in metal ions sensing have been investigated, and the quenching effect of HTP is more sensitive toward transition metal than linear copolymer PTP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 222–230, 2009