Efficient and color pure blue light emitting random copolymer with fluorene and fluorenylstilbene

A blue electroluminescent polymer, random copolymer of fluorenylstilbene and fluorene, was prepared by the nickel catalyzed coupling reaction. The structure and properties of the copolymer were analyzed by various spectroscopic methods. The obtained polymer had good solubility and thermal stability with high T_g. The polymer in thin film emits strong blue luminance (max=468 nm) with narrow bandwidth upon photoexcitation. PL spectrum of the polymer in the film is almost consistent with that of solution one as well as the EL spectrum, indicating that the aggregation and the excimer fluorescence are suppressed by the introduction of fluorenylstilbene comonomer. Moreover, the introduction of fluorenylstilbene comonomer lowered the oxidation potential to lead feasible hole injection, when the compared with poly(fluorene) homopolymer. The ITO/PEDOT/polymer/LiF/Al device showed the maximum brightness of 3500 cd/m² with a turn on voltage of 4.4, the maximum efficiency of 0.878 lm/W and blue emission with CIE chromaticity coordinates of ((x,y)=(0.17, 0.25)).     

Two photoluminescent polymers based on fluorene and 2,4,6‐triphenyl pyridine: Synthesis and electroluminescence

Two fluorene and triphenyl pyridine‐based linear and dendronized copolymers, P1 and P2 , were synthesized and fully characterized by ¹H‐NMR, ¹³C‐NMR, and matrix assistant laser desorption/ionization time‐of‐flight mass spectra, respectively. The absorption, photoluminescence (PL) behavior, and energy band gaps of P1 and P2 relative to those of polyfluorene end‐capped with benzene ( P0 ) were examined through UV–vis, photoluminescent spectra, and cyclic voltammetry. The UV–vis absorption and PL emission behavior of P0 and P1 were hardly affected by molecular architecture, while those of P2 were strongly correlated with the dendronized molecular frameworks. Cyclic voltammetry studies indicated the lower highest occupied molecular orbital energy level and wider band gap of P2 thin solid film relative to those of P0 and P1 . The new polymers were thermally stable up to 410°C. The better luminance and external quantum efficiencies of P1 relative to those of P0 in polymer light‐emitting diode (PLED) applications are due to improved electron injection, charge trapping and recombination at the pyridine sites. Through the experiments, it is found that the triphenyl pyridyl segments and excimers‐formation make pronounced contribution to long wavelength emission in P1 ‐based blue light‐emitting materials, and the analogous materials containing 2,4,6‐triphenyl pyridyl unit of P1 constitute highly attractive materials for white PLED applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Syntheses and photoluminescence properties of UV photocrosslinkable polyesters based on fluorene

Suppression of the green emission for polyfluorene has been widely investigated and various methods have been explored. In the present work, the photocrosslinkable copolyesters based on ferulic acid and 9-hydroxy-9-fluorene-carboxylic acid with different monomer feed molar ratios were synthesized and photocrosslinking reactions were employed to make the copolyesters crosslinked. All the photoluminescence spectra of the polyesters prior to photocrosslinking peaked at 418 nm in chloroform with quantum efficiencies more than 0.65. After crosslinking, copolyester P2 showed better thermo-stability of photoluminescence than the conjugated poly(9,9-dihexylfluorene). This indicated that the crosslinking architecture could suppress the chain aggregation, thus improving the purity of blue emission.     

Single-layer white polymer light-emitting diodes based on an iridium (III) complex containing alkyltrifluorene picolinic acid

To explore the relationship between the electronic properties of a host/dopant system and obtain a high-efficiency single-dopant white polymer light-emitting device two novel blue-emitting cyclometalated iridium (III) complexes of (dfppy)₂Ir(Tfl-pic) and (dfppy)₂Ir(Brfl-pic) have been synthesized and characterized, where dfppy is 2-(2,4-difluorophenyl)pyridine, Tfl-pic and Brfl-pic are picolinic acid derivatives containing trialkylfluorene and dibromoalkylfluorene units bridged with an alkoxy chain, respectively. Both iridium (III) complexes exhibited blue emission in dichloromethane solution and their neat films, and possessed good dispersibility and thermal properties. Two different devices using (dfppy)₂Ir(Tfl-pic) as a single component emitter and a blend of poly(N-vinylcarbazole) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as the host matrix were fabricated. Improved white emission was obtained by adjusting the electron injection layer leading to efficient exciplex emission.     

Studies on Optical Characteristics of Multicolor Emitting MEH-PPV/ZnO Hybrid Nanocomposite

The present work endeavors towards the scientific study on influence of ZnO nanoparticles on the optical characteristics of Poly [2 Methoxy (5, 2′ Ethylhexyloxy)-P-Phenylenevinylene] (MEH-PPV), a light emitting polymer. Hybrid nanocomposites of MEH-PPV were prepared by dispersing ZnO nanorods at loading concentrations of 1 wt. % and 3 wt. %. The structural characteristics of the hybrid composites were investigated using FTIR spectroscopy and X-ray diffraction. The UV absorption spectra and Photoluminescence emission spectra were analyzed in order to study the optical characteristics of nanocomposite. The optical constants were determined and the suitability of the composites for light emission was analyzed. The incorporation of ZnO nanorods facilitates the shift in emission wavelength and witnesses the color tuning ability and multicolor emission from the composite.     

Fast response single‐ion transport light‐emitting electrochemical cell based on PPV derivative

We present the electrical and optical characteristics of a single‐ion transport light‐emitting electrochemical cell (SLEC) based on poly(p‐phenylene vinylene) (PPV) derivative containing aryl‐substituted oxadiazole in the backbone (MEH‐OPPV). Ionized polyurethane–poly(ethylene glycol) (PUI) used as polymer electrolyte is introduced into the active layer of the SLEC. The turn‐on voltage of the SLEC is about 3 V according to its current density–voltage (J–V) characteristics. The response time of the SLEC is less than 10 ms, lower than that of normal LECs by two orders of magnitudes roughly. The reasons of the quick response for the SLEC are discussed in the article. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4253–4255, 2006     

High efficient and high color pure blue light emitting materials: New asymmetrically highly twisted host and guest based on anthracene

New asymmetrically highly twisted anthracene derivatives serve as a matched host and guest material in high efficiency blue OLEDs. 2-(2-Methylnaphtathalene-1-yl)-9,10-di(naphthalene-2-yl)anthracene and N-(4-(10-naphthalene-2-yl)anthracene-9-yl)phenyl-N-phenylnaphthalene-2-amine were prepared as host material and as guest material, respectively. Multilayer organic electroluminecent devices constructed using these foregoing twisted anthracene derivatives as the emitting layer gave quantum efficiencies of 5% and exhibited a pure blue emission with CIE chromaticity coordinates x = 0.15, y = 0.14-0.18.     

Composite polymer electrolytes based on the low crosslinked copolymer of linear and hyperbranched polyurethanes

Low crosslinked copolymer of linear and hyperbranched polyurethane (CHPU) was prepared, and the ionic conductivities and thermal properties of the composite polymer electrolytes composed of CHPU and LiClO₄ were investigated. The FTIR and Raman spectra analysis indicated that the polyurethane copolymer could dissolve more lithium salt than the corresponding polymer electrolytes of the non crosslinked hyperbranched polyurethane, and showed higher conductivities. At salt concentration EO/Li = 4, the electrolyte CHPU30‐LiClO₄ reached its maximum conductivity, 1.51 × 10^?5 S cm^?1 at 25°C. DSC measurement was also used for the analysis of the thermal properties of polymer electrolytes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3607–3613, 2007     

Synthesis of a novel luminescent copolymer based on bisphenol A

A new luminescent copolymer (BPAEt₂‐BP; Scheme 1 ), with short alternating divinylbiphenyl units and O‐diethylated bisphenol A (BPAEt₂), was synthesized via the Wittig reaction. The polymer is fully soluble in common organic solvents and has a number‐average molecular weight of 4600 g mol^?1 with a polydispersity index of 1.79. The structure of the polymer was confirmed by ¹H NMR, ¹³C NMR, FTIR and Raman analysis. Thermal analysis of the polymer showed good stability up to 280 °C. Furthermore, polymer film absorbs at 360 nm and emits in the blue at 426 and 451 nm. The band‐gap calculated from the UV‐vis spectrum was about 2.80 eV. A single‐layer device of the configuration indium tin oxide (ITO)/BPAEt₂‐BP/Al has a relatively low turn‐on voltage of 3 V. Copyright © 2005 Society of Chemical Industry     

Effect of solvent evaporation rate on surface composition in fluoro‐copolymer/acrylate‐copolymer blend films

The relationship between the surface composition and the rate of solvent evaporation (R) in blend films of poly(vinylidene fluoride‐co‐hexafluoroacetone) (P(VDF‐HFA)) and poly(2‐ethylhexyl acrylate‐co‐acrylic acid‐co‐vinyl acetate) (P(2EHA‐AA‐VAc)) has been investigated. P(VDF‐HFA), a low‐surface tension component, was concentrated on the surface when R was relatively high. In contrast, when R was relatively low, P(2EHA‐AA‐VAc), a low‐density component, was concentrated on the surface. Therefore, it is speculated that the factors dominating surface enrichment in polymer blends were changed from surface tension differences to density differences between the components when R was decreased. In addition, the affinity between components and substrate strongly affects the dominant factors determining the surface composition. © 2001 Society of Chemical Industry     

Synthesis of functionalized copolymer electrolytes based on polysiloxane and analysis of their conductivity

Functionalized siloxane-based solid polymer electrolytes were synthesized using a platinum-catalyzed silylation reaction. The ionic conductivities of these solid polymer electrolytes were measured as a function of the concentration of lithium bis(trifluoromethylsulfonyl)imide (LiTFSi) salt. The highest ionic conductivity and lowest activation energy of solid polymer electrolytes were observed to be 1.15 × 10⁻⁴ S cm⁻¹ (25 °C) and 3.85 kJ mol⁻¹, respectively. The interface property between electrolyte and electrode and thermal stability of the polymer electrolytes were found to enhance after they were functionalized with acrylate, and the functionalized electrolytes were observed to maintain a glass transition temperature as low as that of other siloxane compounds. Thus, modifications involving acrylate with ethylene oxide group substitution provide a route for carrier ions and enhance both the ionic conductivity and mechanical properties of the siloxane structure.     

Synthesis of a soluble conjugated copolymer based on dialkyl-substituted dithienothiophene and its application in photovoltaic cells

A soluble conjugated alternating 3,5-didecanyldithieno[3,2-b:2′,3′-d]thiophene-thiophene copolymer was synthesized by palladium(0)-catalyzed Stille coupling reaction. The thermal, absorption, emission, electrochemical, and photovoltaic properties of the polymer were examined. A weight-average molecular weight around 6.2 × 10⁴ and a polydispersity index of 1.8 was estimated for the polymer using gel permeation chromatography. The polymer exhibits good thermal stability with decomposition temperature of 340 °C and glass-transition temperature of 136 °C. The polymer shows strong absorption peaked at 505 nm in diluted solution and 518 nm in thin film with an optical band gap 2.0 eV. The polymer exhibits intense emission located at 550 nm in solution and 603 nm in film. The HOMO and LUMO energies of the polymer were estimated to be −5.4 and −3.4 eV, respectively, by cyclic voltammetry. Polymer solar cells were fabricated based on the blend of the polymer and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). The power conversion efficiency of 0.7% was achieved under AM 1.5, 100 mW/cm² using polymer:PCBM (1:4, w/w) as active layer.     

Proton conducting crosslinked polymer electrolyte membranes based on SBS block copolymer

A series of crosslinked polymer electrolyte membranes with controlled structures were prepared based on poly(styrene‐b‐butadiene‐b‐styrene) (SBS) triblock copolymer and a sulfonated monomer, 2‐sulfoethyl methacrylate (SEMA). SBS membranes were thermally crosslinked with SEMA in the presence of a thermal‐initiator, 4,4′‐azobis(4‐cyanovaleric acid) (ACVA), as confirmed by FT‐IR spectroscopy. The water uptake and ion exchange capacity (IEC) of membranes increased almost linearly with SEMA concentrations due to the increase of SO groups. However, the proton conductivity of membranes increased linearly up to 33 wt % of SEMA, above which it abruptly jumped to 0.04 S/cm presumably due to the formation of well‐developed proton channels. Microphase‐separated morphology and amorphous structures of crosslinked SBS/SEMA membranes were observed using wide angle X‐ray scattering (WAXS), small angle X‐ray scattering (SAXS), and transmission electron microscopy (TEM). The membranes exhibited good mechanical properties and high thermal stability up to 250°C, as determined by a universal testing machine (UTM) and thermal gravimetric analysis (TGA), respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

AM/AMPS共聚物的合成与性质研究

采用过硫酸铵和亚硫酸氢钠氧化还原体系引发丙烯酰胺(AM)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)水溶液进行二元共聚,得到AM/AMPS共聚物。黄金分割法评定确定最佳合成条件为:引发剂0.002 888%,单体20%,AMPS∶AM=20∶80(质量百分比),反应温度45.52℃。用红外光谱(IR)对目标产物进行结构表征,并评价了目标物的溶液性能和稳定性。结果表明,AM/AMPS共聚物的耐温抗盐性优于大庆HPAM聚合物,适用于高温高盐油藏条件。     

Poly(ethylene oxide)‐based block copolymer electrolytes for lithium metal batteries

Nanostructured block copolymer electrolytes (BCEs) based on poly(ethylene oxide) (PEO) are considered as promising candidates for solid‐state electrolytes in high energy density lithium metal batteries (LMBs). Because of their self‐assembly properties, they confer on electrolytes both high mechanical strength and sufficient ionic conductivity, which linear PEO cannot provide. Two types of PEO‐based BCEs are commonly known. There are the traditional ones, also called dual‐ion conducting BCEs, which are a mixture of block copolymer chains and lithium salts. In these systems, the cations and anions participate in the conduction, inducing a concentration polarization in the electrolyte, thus leading to poor performances of LMBs. The second family of BCEs are single‐lithium‐ion conducting BCEs (SIC‐BCEs), which consist of anions being covalently grafted to the polymer backbone, therefore involving conduction by lithium ions only. SIC‐BCEs have marked advantages over dual‐ion conducting BCEs due to a high lithium ion transference number, absence of anion concentration gradients as well as low rate of lithium dendrite growth. This review focuses on the recent developments in BCEs for applications in LMBs with particular emphasis on the physicochemical and electrochemical properties of these materials. © 2018 Society of Chemical Industry     

Thermo-responsive shape memory properties based on polylactic acid and styrene-butadiene-styrene block copolymer

This study aims to compare thermal, mechanical, and shape memory behavior of polylactic acid (PLA) blended with different structures of styrene-butadiene-styrene block copolymer (SBS), namely linear SBS (L-SBS), and radial SBS (R-SBS). The amount of L-SBS and R-SBS added was varied between 10 and 70 wt%, and the blending process was carried out using an internal mixer at 180°C before the shaping process by the compression molding. An improvement in the degree of crystallinity was observed across the entire composition range with less pronounced transition temperature change. Tensile strength and modulus of PLA/L-SBS blends were higher than PLA/R-SBS blends across all composition ranges. The results also revealed that the shape fixing ratio (R_f) and recovery ratio (R_r) of PLA/L-SBS were higher than PLA/R-SBS, with PLA70/SBS30 showed the best shape memory behavior. The morphology characteristics of the blend were also examined with the scanning electron microscope.     

Creep rupture properties of homopolymer,copolymer, and terpolymer based on poly(oxymethylene)

Polyacetal copolymers were prepared by cationic ring‐opening copolymerizations of 1,3,5‐trioxane (TOX) with 1,3‐dioxolane (DOX), and polyacetal terpolymers were prepared by terpolymerizations of TOX, DOX, and 2‐ethylhexyl glycidyl ether (EHGE). Polyacetal polymers with three different structures such as polyacetal homopolymers, polyacetal copolymers, and polyacetal terpolymers were compared in the mechanical properties and the creep characteristics, and discussed from the view point of the polymer structure. The polyacetal copolymers and the polyacetal terpolymers were determined by ¹H‐MNR measurement. About 80 mol % of DOX and EHGE amounts in feed were incorporated randomly into the each polymer. From the plots of the degree of crystallinity (X_c) versus the tensile strength, the tensile strength and crystallintiy of the polyacetal homopoymers are higher than those of the polyacetal copolymers and the polyacetal terpolymers. However, the tensile strength does not decrease linearly with a decrease in the crystallinity among the polyacetal polymers with three different structures, the polyacetal homopolymer, the polyacetal copolymers, and the polyacetal terpolymers. Creep rupture was characterized by the activation volume, υ_c, value in Zhurkov's equation, which can be estimated from the slope in the plots of load versus log (rupture time) at 80°C. The polyacetal polymers with higher molecular weight have larger values of the activation volume than those with lower molecular weight. When the activation volume values are compared among the polyacetal polymers with the same molecular weights, they increase in the following order: the polyacetal homopolymers < the polyacetal copolymers < polyacetal terpolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

丙烯腈-苯乙烯磺酸共聚物/层状双金属氢氧化物纳米复合质子传导聚合物电解质的制备与表征

Acrylonitrile-sodium styrene sulfonate copolymer/layered double hydroxides nanocomposites were prepared by in situ aqueous precipitation copolymerization of acrylonitrile （AN） and sodium styrene sulfonate （SSS） in the presence of 4-vinylbenzene sulfonate intercalated layered double hydroxides （MgA1-VBS LDHs） and transferred to acrylonitrile-styrene sulfonic acid （AN-SSA） copolymer/LDHs nanocomposites as a proton-conducting polymer electrolyte. MgA1-VBS LDHs were prepared by a coprecipitation method, and the structure and composition of MgAl-VBS LDHs were determined by X-ray diffraction （XRD）, infrared spectroscopy, and elemental analysis. X-ray diffraction result of AN-SSS copolymer/LDHs nanocomposites indicated that the LDHs layers were well dispersed in the AN-SSS copolymer matrix. All the AN-SSS copolymer/LDHs nanocomposites showed significant enhancement of the decomposition temperatures compared with the pristine AN-SSS copolymer, as identified by the thermogravimetric analysis. The methanol crossover was decreased and the proton conductivity was highly enhanced for the AN-SSA copolymer/LDHs nanocomposite electrolyte systems. In the case of the nanocomposite electrolyte containing 2% （by mass） LDHs, the proton conductivity of 2.60×10^- 3 S·m^-1 was achieved for the polymer electrolyte.     

Effect of a styrene–butadiene copolymer on the phase structure and impact strength of polyethylene/high‐impact polystyrene blends

The effect of a styrene–butadiene block copolymer on the phase structure and impact strength of high‐density and low‐density polyethylene/high‐impact polystyrene blends with various compositions was studied. For both the blends, the type of the phase structure was not affected by addition of a styrene–butadiene compatibilizer. The localization and structure of the compatibilizer in the blends were dependent on their composition. Addition of the compatibilizer improved impact strength of the blends in the whole concentration range. The improvement was the largest for blends with a low amount of the minor phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 570–580, 2001