一种合成聚(2-甲氧基-5-(2′-乙基-己氧基)-对苯乙炔)的新方法

聚对苯乙炔 (ＰＰＶ)及其衍生物是制备聚合物发光二极管的最重要的聚合物之一[1] .这主要是因为它们具有优越的电致发光性能 ,易于合成以及良好的环境稳定性[2 ] .而聚 (2 甲氧基 5 (2′ 乙基 己氧基 ) 对苯乙炔 ) (ＭＥＨ ＰＰＶ)由于其可溶性好 ,发光效率和亮度高 ,在电致发光领域广受关注 .现在有许多ＭＥＨ ＰＰＶ的多步化学合成方法以及电化学合成方法 .但是 ,这些方法常常产率低 ,成本高且产品不纯 .本文报道一种固 液两相反应一步合成分子量大、溶解性好的ＭＥＨ ＰＰＶ的新方法 .1　主要原料对甲氧基苯酚 (纯度≥ 98% ,Ａｌｄｒ…     

Synthesis and characterization of novel poly(2-methoxy-(5-(6′-dimethylphosphonate)-hexyloxy)-1,4-phenylenevinylene-ran-2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene)s (MEH-PO-PPVs) and their tunable emission colors

Poly(2-methoxy-(5-(6′-dimethylphosphonate)-hexyloxy)-1,4-phenylenevinylene-ran-2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PO-PPV) was synthesized via Heck coupling reaction of MPOHOB-2Br (1) (1-methoxy-(4-(6-dimethylphosphonate)-hexyloxy)-2,5-dibromobenzene), MEHOB-2Br (2) (1-methoxy-4-(6-bromohexyloxy)-2,5-dibromobenzene), and MEHOB-DV (4) (1-methoxy-4-(2′-ethylhexyloxy)-2,5-divinylbenzene) by varying the molar ratios of monomers. The monomers and their intermediates were characterized by ¹H NMR, FT-IR, and melting point and elemental analyzer, and subsequent polymers by FT-IR, ¹H NMR, GPC, DSC, TGA, and solubility test. The optical (UV-vis, PL) and electrical properties (CV) of polymers were also evaluated. MEH-PO-PPV, containing phosphine oxide groups, exhibited better solubility, lower HOMO and LUMO levels, and larger band gaps. In addition, the PL emission gradually shifted to shorter wavelength, providing 570 (MEH-10PO-PPV), 519 (MEH-30PO-PPV), and of 465 nm (MEH-50PO-PPV) as the PO content increased, compared with 598 nm (MEH-PPV).     

Synthesis of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene-silica core-shell particles with a self-templating method and their fluorescent properties

Sub-micrometer particles with poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) cores coated by silica-based shells were prepared with a self-templating method and their fluorescent properties were investigated in this paper. The characteristic of this method was that all reactions could be finished in one-pot, which exempted from removing the template and reduced reaction steps compared to the conventional process. Emission wavelength of the resultant core-shell particles can readily be tuned through chemical modification of MEH-PPV, which was carried out via regulating the conjugation length of the polymer. In addition, the size of MEH-PPV/SiO₂ core-shell particles could be controlled by altering reaction conditions. The obtained particles had clear core-shell structure and may be used as biolabeling materials. The morphologies, particle size distribution and fluorescent properties of MEH-PPV/SiO₂ particles were characterized by transmission electron microscopy (TEM), particle size analyzer and fluorescence emission spectra, respectively.     

Polymer-polymer rectifying heterojunction based on poly(3,4-dicyanothiophene) and MEH-PPV

Thin, homogeneous films of a high electron affinity (n-dopable) polymer, poly(3,4-dicyanothiophene) (PDCTh), were prepared by in-situ thermal polymerization of 2,5-diiodo-3,4-dicyanothiophene on substrates. As a result of the presence of two cyano substituents on the thiophene backbone, PDCTh is an electronegative polymer, with the LUMO at ca. 3.6 eV and the HOMO at ca. 6.7 eV. We demonstrate the fabrication of polymer-polymer rectifying heterojunctions using PDCTh and poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) polymer layers on ITO-glass. Rectification ratios in the current voltage characteristics of these devices exceed 10.³ This device exhibits a photovoltaic effect with a dc sensitivity at -3 V reverse bias of 4 × 10^-4 A/W or quantum yield of 0.1% electrons/photon. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3115–3120, 1998     

Application of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] for splitting of single-walled carbon nanotube bundles in polystyrene/SWCNT composite

Dispersions of single-walled carbon nanotubes (SWCNTs) in organic solutions containing poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were studied by Raman spectroscopy, UV-vis-NIR spectroscopy, and electron microscopy. This polymer interacts with the nanotube resulting in the appearance of a new red-shifted absorption band in the electronic spectrum. This indicates the formation of a charge-transfer complex between MEH-PPV and SWCNTs. Additives of MEH-PPV make it possible to achieve stable suspensions of nanotubes in styrene. A polystyrene/SWCNT/MEH-PPV composite with a high degree of bundle splitting was obtained by polymerization. It was shown that the luminescence intensity of the nanotubes in the Raman spectrum can serve as a indicator for the estimation of the degree of splitting of SWCNT bundles in the composite.     

New luminescent polymers for leds and LECS

Statistical copolymers 5 containing poly(2-dimethyloctylsilyl-1,4-phenylenevinylene) (DMOS-PPV) and poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) have been synthesized using the dehydrohalogenation condensation route. The copolymers show a shift of photoluminescence maxima to longer wavelengths as the proportion of the MEH-PV unit increases. This trend is accompanied by reduced efficiencies and lower turn-on voltages in single layer electroluminescent devices. Light-emitting electrochemical cells (LECs) have been prepared using a blend of DMOS-PPV 1 with poly(ethylene oxide)/lithium triflate and the homopolymer poly[2-methoxy-5-(triethoxymethoxy)-1,4-phenylene vinylene] (MTEM-PPV) 9 with lithium triflate. In comparison with single-layer devices which were fabricated using the homopolymers 1 and poly[2,5-bis(triethoxymethoxy)-1,4-phenylene vinylene] (BTEM-PPV) 10 , the LEC devices showed lower turn-on voltages.     

Enhanced electrochromic absorption in Ag nanoparticle embedded conjugated polymer composite films

Ag/MEH-PPV {poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]} composite films were prepared by the pulse current electrodeposition of Ag nanoparticles followed by spin coating of MEH-PPV and their enhanced electrochromic coloration was investigated. A relatively uniform Ag nanoparticle array was obtained by the electrodeposition and distinct plasmon absorption bands of Ag nanoparticles were observed. The absorption maximum of Ag/MEH-PPV was much higher than that of MEH-PPV, indicating that the Ag nanoparticles induced an enhanced absorption. In addition, the electrochromic absorption was 1.6 times higher at 500 nm wavelength, with a clearly different coloration compared to MEH-PPV.     

Synthesis of hybrid solar cells using CdS nanowire array grown on conductive glass substrates

High-density CdS nanowire (NW) arrays were successfully grown on fluorine-doped tin oxide (FTO)-coated glass substrates by vapor–liquid–solid (VLS) mechanism at a remarkably reduced temperature of ～450 °C. Bi catalyst layer and polyvinyl alcohol (PVA) played a major role in the low-temperature synthesis of high-quality CdS NW arrays. CdS NWs were defect free single crystalline Wurtzite crystals and they were 50–100 nm and 2–5 μm in diameter and length, respectively. CdS NWs were combined with poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), a conjugated polymer to form organic–inorganic hybrid structures. The UV–visible light absorption and emission behavior of MEH-PPV/CdS hybrids was investigated and their potential to be used as photovoltaic cells was demonstrated.     

Vinyl copolymers containing pendant 1,3,4-oxadiazole chromophores: Preparation and electrochemical and electroluminescent properties

Three vinyl copolymers (P1–P3) containing pendant aromatic 1,3,4-oxadiazole derivatives were prepared from their precursor poly(styrene-ran-4-vinylbenzyl chloride) (weight-average molecular weight = 11,400, polydispersity index = 1.18), which had been synthesized by controlled radical polymerization (reversible addition–fragmentation chain transfer). The copolymers were readily soluble in common organic solvents and were basically amorphous materials with 5% weight loss temperatures higher than 360°C. The photoluminescence spectroscopy results revealed that the architectures of P2 and P3 suppressed aggregate formation in the solid state. The LUMO levels of P2 (−3.10 eV) and P3 (−3.09 eV), estimated from cyclic voltammetry data, were much higher than that of P1 (−3.81 eV). The HOMO levels were in the order of P3 (−5.37 eV) > P2 (−5.77 eV) > P1 (−5.96 eV). However, both the HOMO and LUMO levels of P1–P3 were much lower than that of poly[2-methoxy-5-(2′-ethylhexoxy)-p-phenylenevinylene] (MEH-PPV) because of the electron-withdrawing characteristics of the pendant aromatic 1,3,4-oxadiazole groups. The luminance (5860 cd/m²) and current efficiency (1.45 cd/A) of an electroluminescence device [indium tin oxide/poly(3,4-ethylene dioxythiophene)/MEH-PPV/Al] were improved significantly to 16,261 cd/m² and 4.79 cd/A, respectively, through blending with P2 (50/50). This study suggests that copolymers P1–P3 are versatile materials for electron-transport/injection applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2259–2272, 2007     

Preparation and characterization of a novel poly(1,4-phenylenevinylene) derivative with an azobenzene side chain

A novel poly(1,4-phenylenevinylene) (PPV) derivative containing an azobenzene side chain was prepared via a dehydrochlorination route. Poly{2-methoxy-5-[(4-(4-methoxyphenylazo)phenyloxy)-hexyloxy]-1,4-phenylenevinylene}, which is soluble in ordinary solvents such as chloroform, tetrahydrofuran (THF), acetone, xylene, etc., was characterized by FTIR, ¹H NMR, GPC, and UV-visible spectroscopies, thermogravimetric analysis (TGA), and cyclic voltammetry. The photoluminescence spectrum of the polymer showed an emission maximum at λ = 550 nm.     

Electrochemical and optical characterization of p- and n-doped poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene

We study electrochemical p- and n-type doping in the well-known light-emitting polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Doping reactions are characterized using cyclic voltammetry. Optical measurements including photoluminescence and UV/Vis/NIR transmission were performed on doped samples. We find that oxidation in MEH-PPV is a highly reversible reaction resulting in stable freestanding doped films, while the reduced form is unstable and the reaction irreversible. We discuss the dependence of doping reactions on scan rate, film thickness, salt type and concentration, and working electrode type. We observe the development of two additional broad absorption bands in both lightly and heavily doped films accompanied by a slight blueshift in the primary optical transition, suggesting bipolaron band formation. Finally we find that both p and n dopings result in extremely sensitive photoluminescence quenching. We propose a physical model for understanding electrochemical doping in MEH-PPV and the implications this has on the development of such technologies as polymer light-emitting electrochemical cells, electrochromic devices, actuators, and sensors.     

Aging of poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)/toluene solutions and subsequent effects on luminescence behavior of cast films

Morphological effects in luminescence properties of a representative semiconducting polymer, poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV), has recently attracted much attention. Previous studies indicated that short-term heat treatment of solution-cast MEH-PPV films may result in the formation of mesomorphic order that is responsible for the "red" emission around 640 nm, in contrast to the single-chromophore "yellow" emission near 590 nm from the disordered matrix. On the basis of microscopic and spectroscopic evidence for films cast from freshly prepared and aged solutions, here we show that prolonged storage of MEHyellowPPV solutions at room temperature or lower may result in retardation of the thermally induced mesophase formation in the subsequently cast films. According to small-angle neutron scattering and differential scanning calorimetric observations over aged MEH-PPV/toluene solutions, we propose that the suppressed transformation into mesomorphic order is due to further development of nanocrystalline aggregates that serve as physical cross-links among MEH-PPV chains in the solution state upon long-term storage. These solvent-induced nanocrystalline aggregates, however, do not exhibit new spectroscopic features beyond the suppression of "red" emission at 640 nm from the mesomorphic phase.     

Surface modification of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) by confined photo-catalytic oxidation

In this study, the surface of π-conjugated polymer, poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), was successfully modified with the sulfate anion (SO(4-)) groups by the confined photo-catalytic oxidation (CPO). After the surface modification, the water contact angle of MEH-PPV is changed from 95.5° to 82.1° without influence on its optical properties (based on the UV and PL spectra), and the water droplet can be absorbed on the modified MEH-PPV surface without sliding even at substrate tilt angles of 90° and 180°. The CPO on the MEH-PPV surface is able to further expand the use of MEH-PPV for applications. In addition, the water transport test indicates that the modified MEH-PPV can be a candidate for transporting water droplet.     

Syntheses and electroluminescence properties of conjugated poly(p‐phenylene vinylene) derivatives bearing dendritic pendants

A series of new poly(p‐phenylene vinylene) derivatives with different dendritic pendants—poly{2‐[3′,5′‐bis(2″‐ethylhexyloxy)benzyloxy]‐1,4‐phenylenevinylene} (BE–PPV), poly{2‐[3′,5′‐bis(3″,7″‐dimethyl)octyloxy]‐1,4‐phenylenevinylene} (BD–PPV), poly(2‐{3′,5′‐bis[3″,5″‐bis(2?‐ethylhexyloxy)benzyloxy]benzyloxy}‐1,4‐phenylenevinylene) (BBE–PPV), poly(2‐{3′,5′‐bis[3″,5″‐bis(3?,7?‐dimethyloctyloxy)benzyloxy]benzyloxy}‐1,4‐phenylenevinylene) (BBD–PPV), and poly[(2‐{3′,5′‐bis[3″,5″‐bis(2?‐ethylhexyloxy)benzyloxy]benzyloxy}‐1,4‐phenylenevinylene)‐co‐(2‐{3′,5′‐bis[3″,5″‐bis(3?,7?‐dimethyloctyloxy)benzyloxy]benzyloxy}‐1,4‐phenylenevinylene)] (BBE‐co‐BBD–PPV; 1:1)—were successfully synthesized according to the Gilch route. The structures and properties of the monomers and the resulting conjugated polymers were characterized with ¹H and ¹³C NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, ultraviolet–visible absorption spectroscopy, photoluminescence, and electroluminescence spectroscopy. The obtained polymers possessed excellent solubility in common solvents and good thermal stability, with a 5% weight loss temperature of more than 328 °C. The weight‐average molecular weights and polydispersity indices of BE–PPV, BD–PPV, BBE–PPV, BBD–PPV, and BBE‐co‐BBD–PPV (1:1) were in the range of 1.33–2.28 × 10⁵ and 1.35–1.53, respectively. Double‐layer light‐emitting diodes (LEDs) with the configuration of indium tin oxide/polymer/tris(8‐hydroxyquinoline) aluminum/Mg:Ag/Ag devices were fabricated, and they emitted green‐yellow light. The turn‐on voltages of BE–PPV, BD–PPV, BBE–PPV, BBD–PPV, and BBE‐co‐BBD–PPV (1:1) were approximately 5.6, 5.9, 5.5, 5.2, and 4.8 V, respectively. The LED devices of BE–PPV and BD–PPV possessed the highest electroluminescent performance; they exhibited maximum luminance with about 860 cd/m² at 12.8 V and 651 cd/m² at 13 V, respectively. The maximum luminescence efficiency of BE–PPV and BD–PPV was in the range of 0.37–0.40 cd/A. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3126–3140, 2005     

Electrical conductivity and photoconductivity of films of composites based on poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] with additions of zinc octabutyl phthalocyanine and C60

Features of the photoconductivity of films of composites based on [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] with additions of zinc 2,3,9,10,16,17,23,24-octabutylphthalocyanine and C₆₀ were studied. Luminescence quenching and an increase in the photoconductivity with the addition of C₆₀ to their composition were detected. The increase in the photoconductivity is connected with the capture of electrons and their transport along the C₆₀ molecules. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 271–275, September–October, 2006.     

Effect of metal nanoparticles on the optical properties of the solutions of porphyrinates and MEH-PPV polymer

The interactions of metal nanoparticles, which were synthesized in inverse micelles, with a number of porphyrinate molecules and a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) polymer in solutions were examined by spectrophotometry in order to study the effects of various additives on the efficiency of sun energy absorption and conversion by photosensitive polymer layers. The optical absorption and luminescence spectra of the solutions of Ag, Pd, and Pt nanoparticles and the solutions of Pd(II) and Pt(II) meso-tetra(benzo-15-crown-5)porphyrinates and the MEH-PPV polymer were measured previously.     

Synthesis of Exfoliated MEH-PPV/Clay Nanocomposites

The synthesis of poly（2-methoxy-5-（2＇-ethyl-hexyloxy）-l,4-phenylenevinylene） （MEH-PPV） in the presence of organophilic montmorillonite （OMMT） was reported and the exfoliated MEH-PPV/OMMT nanocomposites was obtained by controlling the ratio of the monomer to the OMMT.     

A solid-contact Pb-selective electrode using poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) as ion-to-electron transducer

In this work, a novel all-solid-state polymeric membrane Pb²⁺-selective electrode was developed by using for the first time poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) as solid contact. To demonstrate the ion-to-electron transducing ability of MEH-PPV, chronopotentiometry and electrochemical impedance spectroscopy measurements were carried out. The proposed electrodes showed a Nernstian response of 29.1 mV decade⁻¹ and a lower detection limit of subnanomolar level. No water film was observed with the conventional plasticized PVC membrane. This work demonstrates a new strategy for the fabrication of robust potentiometric ion sensors.     

Synthesis and characterization of alt‐bipyridinylene‐phenylene copolymers containing ruthenium(II) complexes

Poly{bis(4,4′‐tert‐butyl‐2,2′‐bipyridine)–(2,2′‐bipyridine‐5,5′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3a ), poly{bis(4,4′‐tert‐butyl‐2,2′‐bipyridine)–(2,2′‐bipyridine‐4,4′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3b ), and poly{bis(2,2′‐bipyridine)–(2,2′‐bipyridine‐5,5′‐diyl‐[1,4‐phenylene])–ruthenium(II)bishexafluorophosphate} ( 3c ) were synthesized by the Suzuki coupling reaction. The alternating structure of the copolymers was confirmed by ¹H and ¹³C NMR and elemental analysis. The polymers showed, by ultraviolet–visible, the π–π* absorption of the polymer backbone (320–380 nm) and at a lower energy attributed to the d–π* metal‐to‐ligand charge‐transfer absorption (450 nm for linear 3a and 480 nm for angular 3b ). The polymers were characterized by a monomodal molecular weight distribution. The degree of polymerization was approximately 8 for polymer 3b and 28 for polymer 3d . © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2911–2919, 2004     

Synthesis and electroconductivities of poly(2-methoxy-5-methythio-1,4-phenylene vinylene) and copolymers

Poly(2-methoxy-5-methylthio-1,4-phenylene vinylene), PMTPV, and copolymers containing both unsubstituted or 2,5-dimethoxy-substituted and 2-methoxy-5-methylthio-1,4-phenylene vinylene units were prepared in thin films from their water-soluble, sulfonium salt precursor polymers. Doping of drawn and undrawn films of PMTPV with I₂ vapor led to conductivities of 10^?4–10^?3 S cm^?1, which is significantly lower than those reported for poly(2,5-dimethoxy-1,4-phenylene vinylene). Conductivity of I₂-doped copolymer films ranges from 10^?3–10⁰ S cm^?1 depending on composition.