SCLCPs are synthesized using “click chemistry”. The resulting polymers, P1 and P2, have good solubilities and molecular‐weight distributions. Their and polydispersities are in the ranges of 26.7–8.4 × 103 g · mol?1 and 1.99–1.29, respectively. DSC and POM studies reveal that both polymers exhibit liquid‐crystalline behavior. P1 and P2 are found to display blue emission. DSSCs are fabricated using P1 and P2 as matrices for electrolytes. The maximum PCE of the P1‐ and P2‐based polymer electrolytes is 4.11% (at 1 sun). This synthesis route has again proven to be a useful synthetic methodology for fabricating SCLCPs that are promising materials for device applications.
Benzo[1,2‐b:4,5‐b′]diselenophene (BDS) has been incorporated for the first time in a polymer. bis(Stannyl)‐functionalized BDS was copolymerized with 3,3′‐bis(alkyl)‐5,5′‐bithiophenes (dodecyl and tetradecyl side chains) through Stille copolymerization, to yield p‐type polymer semiconductors for organic field‐effect transistor application. The electronic and structural effect of the selenium atoms, compared to sulphur atoms in analogous copolymers, is described. The molecular weight has a decisive influence on the photophysical properties and supramolecular ordering, expressed in field‐effect transistor measurements. Saturation mobilities around 10?2 cm2 · V?1s?1 are obtained on standard silicon substrates.
π‐Conjugated polymers composed of dialkoxybenzo[1,2‐b:4,5‐b′]dithiophene and thiophenes bearing cyano‐alkoxycarbonylethenyl [? CH?C(CO2R)CN] and bis(alkoxycarbonyl)ethenyl groups [? CH?C(CO2R)2] were prepared. The optical properties of the obtained polymers were investigated by UV‐vis and photoluminescence spectroscopy to demonstrate that the absorption maxima of the polymers were tunable by varying the substituent of thiophene unit. The photoluminescence wavelengths and intensities of the polymer in solution were significantly dependent on the polymer side chain. The HOMO energy level of the polymer was lowered by up to ?5.51 eV by introducing electron‐deficient cyano groups. Polymer solar cells based on the new polymers were fabricated to achieve a PCE of 1.90%.
Summary: With the progress of organic electronics, materials possessing various functionalities are attracting much attention. Here we have synthesized a novel photo‐alignment polymer composed of a conjugated carbazole main‐chain and a coumarin side‐chain through nickel(0)‐mediated polymerization. Carbazole is a well‐known hole transporting material and coumarin is also famous for its good photo‐alignment properties. The photochemical reactivity of the coumarin side‐chain was monitored by UV‐vis spectroscopy and the liquid crystal (LC) photo‐alignment direction of the polymer film was proved to be perpendicular to the polarization direction of the irradiated UV light. The highest occupied molecular orbital (HOMO) level of the polymer, measured from both cyclic voltammetry and photoelectron spectroscopy, was ?5.32 eV. Organic light‐emitting diodes (OLEDs) of the configuration [ITO/polymer/NPB/Alq3/LiF/Al] showed a higher efficiency (2.17%) and brightness (14 000 cd · m?2) than a control device due to enhanced charge balance.
Novel polymer electrolyte materials based on a polyelectrolyte‐in‐ionic‐liquid principle are described. A combination of a lithium 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPSLi) and N,N′‐dimethylacrylamide (DMMA) are miscible with the ionic liquid, 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIDCA). EMIDCA has remarkably high conductivity (≥ 2 · 10?2 S · cm?1) at room temperature and acts as a good solvating medium for the polyelectrolyte. At compositions of AMPSLi less than or equal to 75 mol‐% in the copolymer (P(AMPSLi‐co‐DMAA)), the polyelectrolytes in EMIDCA are homogeneous, flexible elastomeric gel materials at 10 ? 15 wt.‐% of total polyelectrolyte. Conductivities higher than 8 · 10?3 S · cm?1 at 30 °C have been achieved. The effects of the monomer composition, polyelectrolyte concentration, temperature and lithium concentration on the ionic conductivity have been studied using thermal and conductivity analysis, and pulsed field gradient nuclear magnetic resonance techniques.
Comparison of the measured and calculated lithium conductivity at 30 °C. 相似文献
Biodegradable and photocurable block copolymers of ε‐caprolactone and L ‐lactide were synthesized by polycondensation of PLLA diol ( = 10 000 g · mol?1), PCL diol ( = 10 000 g · mol?1), and a chain extender bearing a coumarin group. The effect of copolymer composition on the thermal and mechanical properties of the photocured copolymers was studied by means of DSC and cyclic tensile tests. An increase in Young's modulus and a decrease in the tensile strain with increasing PLLA content was observed for the block copolymers. Block copolymers with high PCL content showed good to excellent shape‐memory properties. Random copolymers exhibited Rf and Rr values above 90% at 45 °C for an extremely large tensile strain of 1 000%.
New carbazole‐based copolymers, which contain various concentrations of 9‐alkyl‐3,6‐carbazole fragments in the main chain connected via alkylene spacers, have been synthesized by Ni(0)‐catalyzed Yamamoto‐type aryl‐aryl coupling reactions. Full characterization of the copolymer structure by NMR spectroscopy and elemental analysis is presented. These compounds represent amorphous materials of high thermal stability with glass transition temperatures of 151–162 °C and thermal decomposition starting at temperatures >390 °C. UV‐Vis absorption and photoluminescence emission of the copolymers confirmed that the effectively conjugated segment in the 3,6‐linked carbazole‐type copolymers is limited to dyads (dimeric units). However, copolymers with varying concentrations of the oligocarbazole chromophores demonstrate different charge injection and transport properties in multilayer light‐emitting diodes with the copolymers as the hole transport and Alq3 as the electroluminescent/electron transport layer. The device based on a copolymer composed of oligocarbazole blocks with an average length of around four carbazoles exhibited the best overall performance with a turn‐on voltage of 3.5 V, a maximal photometric efficiency of 4.1 cd · A?1 and maximum brightness of about 4 200 cd · m?2.
Cyclic polystyrene‐block‐polyisoprenes of controlled dimensions have been synthesized for the first time by the direct coupling of α‐isopropylidene‐1,1‐dihydroxymethyl‐ω‐diethylacetal‐heterodifunctional linear polystyrene‐block‐polyisoprene precursors previously prepared by living anionic polymerization. Cyclization is achieved under high dilution by intramolecular coupling of the polymer ends under acid catalyst conditions. Using this strategy polystyrene‐block‐polyisoprene macrocycles of controlled chain dimensions are prepared in high yield (> 90%). Pure cycles were finally recovered by flash chromatography. The synthesis and characterization of both the linear α,ω‐heterodifunctional polystyrene‐block‐polyisoprenes block copolymers precursors and of the corresponding cyclized chain architectures are reported.
Poly(4,4‐bis[(3,5‐diethoxybenzoyloxy)methyl]‐1,6‐heptadiyne) is synthesized via cyclopolymerization using modified Grubbs‐ and Schrock‐type initiators. Doping with either I2 or NO+ BF4? yields a conductive polymer with conductivity up to 1.4 × 10?2 S cm?1. The undoped amorphous conjugated polymer is spun into monofilament and multifilament fibers by a wet‐spinning process. Fibers are collected on bobbins with a draw down ratio of 12 resulting in fiber diameters under 60 μm, characterized by scanning electron microscopy. X‐ray diffraction data confirms that the amorphous structure of the polymer is preserved; no additional orientation of the polymer chains occurs during fiber spinning.
Cross‐linked poly(3,4‐ethylenedioxythiophene) (PEDOT) films were synthesized by the oxidative polymerization of 3,4‐ethylenedioxythiophene in the presence of five different conjugated and non‐conjugated cross‐linkers. The concentration and structure of the cross‐linker was systematically varied to explore the influence on the electrical conductivity. Optimized compositions displayed an electrical conductivity of up to ≈800 S · cm?1; this corresponds to a conductivity increase of up to 36% compared to linear PEDOT prepared under identical conditions. An increase in the conductivity was only observed for the conjugated cross‐linkers that were incorporated in low concentrations, typically at a level of less than 2 mol‐%. Attempts to incorporate higher concentrations of cross‐linker led to phase separation and crystallization of the cross‐linker and afforded materials in which a significant reduction of the electrical conductivity was observed. The optical properties of the polymer were only marginally affected upon cross‐linking, even at high cross‐linker concentrations.
Low‐molecular‐weight liquid polybutadienes (1 000–2 000 g · mol?1) consisting of 60 mol‐% poly(buta‐1,2‐diene) repeating units were synthesized via anionic telomerization. Maintaining the initiation and reaction temperature at less than 70 °C minimized chain transfer and enabled the polymerization to occur in a living fashion, which resulted in well‐controlled molecular weights and narrow polydispersity indices. MALDI‐TOF mass spectrometry confirmed that the end groups of liquid polybutadienes synthesized via anionic telomerization contained one benzyl end and one protonated end. In comparison, the end groups of liquid polybutadienes synthesized via living anionic polymerization contained one sec‐butyl or butyl end and one protonated end.
1,2,4‐triazole‐functional PGMA polymers have been synthesized and their anhydrous proton‐conducting properties were investigated after doping with phosphoric acid and triflic acid. PGMA was prepared by solution polymerization and then modified with 1H‐1,2,4‐triazole (Tri) and 3‐amino‐1,2,4‐triazole (ATri). FT‐IR, 13C NMR and elemental analysis verify the high immobilization of the triazoles in the polymer chain. Phosphoric‐acid‐doped polymers showed lower Tg and higher proton conductivities. PGMA‐Tri 4 H3PO4 showed a maximum water‐free proton conductivity of approximately 10?2 S · cm?1 while that of PGMA‐ATri 2 H3PO4 was 10?3 S · cm?1. The structure and dynamics of the polymers were explored by 1H MAS and 13C CP‐MAS solid‐state NMR.
In order to understand the contribution of nanoparticle surface area to the properties of nanocomposite materials, hydroxyapatite nanoparticles with different specific surface areas (60 m2 · g?1 and 111 m2 · g?1) were synthesized using reverse microemulsion and processed into nanocomposites. Experimental results indicated that the thermomechanical reinforcement did show a dependence on nanoparticle surface area, although the transition temperatures did not. The reinforcement trends were dependent on temperature, suggesting that the nanoparticles had a greater impact on the amorphous polymer chains. The reinforcement above Tg may be plotted against nanoparticle surface area to obtain a single reinforcement trend, suggesting that surface area is a general parameter for nanocomposite property control.
Two terthiophenes bearing core fluorinated thienyl units have been synthesised as potential semiconductor materials for organic field‐effect transistors. Polymerisation of these compounds has been achieved using conventional iron(III) chloride oxidative coupling methods and by electrochemical oxidation. Characterisation of the fluorinated materials has been achieved by absorption spectroscopy and cyclic voltammetry. A soluble hexyl‐functionalised polymer (poly 8b ) was used in an OFET device; hole mobilities were measured up to 3 × 10?3 cm2 · V?1 · s?1, and the device had an on/off ratio of 105 and a turn‐on voltage of +4 V.
A series of anthracene‐based conjugated copolymers containing 9,10‐bis(6‐bromonaphthalen‐2‐yl)‐2‐tert‐butylanthracene (BNA) and 2,7‐diphenyl substituted fluorene (DPPF) moieties are prepared via a palladium‐catalyzed Suzuki polymerization. All of the synthesized polymers emit blue light at around 450 nm and show good thermal and color stability. Their electroluminescence spectra remain unchanged at high driving voltage. The double‐layer polymer light‐emitting diode (PLED) fabricated with ITO/PEDOT:PSS/DPPFBNA3/CsF/Al, produces a maximum brightness of 1 650 cd · m?2 and has a luminance efficiency of 0.39 cd · A?1. The ITO/PEDOT:PSS/TFB/DPPFBNA3/CsF/Al multilayer PLED, incorporating a TFB layer to facilitate hole transportation, produces a maximum brightness of 5 371 cd · m?2 and a luminance efficiency of 1.18 cd · A?1.
A new high‐mobility low‐bandgap polymer, PBDT‐DODTBT, based on benzodithiophene and 5,6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzothiadiazole has been synthesized through a standard Stille coupling reaction. The polymer is soluble in common organic solvents, such as chloroform, tetrahydrofuran, and chlorobenzene and has excellent film forming properties. Preliminary studies of the copolymer showed the charge mobility as high as 7.15 × 10?3 cm2 · V?1 · s?1 from SCLC measurement. Initial photovoltaic cells based on the composite structure of ITO/PEDOT:PSS/PBDT‐DODTBT: α PC71BM (1:2)/Ca/Al showed an open‐circuit voltage of 0.76 V, a power conversion efficiency of 4.02%, and a short‐circuit current of 8.96 mA · cm?2.
We synthesized a phenoxymethyl‐substituted polystyrene (PHP) and a series of 4‐alkylphenoxymethyl‐substituted polystyrenes, where the alkyl group is ? (CH2)nH (n = 1, 2, 4, 6, and 8), using polymer analogous reactions, in order to study the effect of the phenoxymethyl and 4‐alkylphenoxymethyl side groups on the liquid crystal (LC) alignment properties. The LC cell fabricated with the rubbed PHP film exhibited homogeneous planar and perpendicular LC alignment with respect to the rubbing direction. On the contrary, the LC cells made from the 4‐alkylphenoxymethyl‐substituted polystyrenes showed homeotropic LC alignment behaviors even at a very high rubbing density of 250, regardless of the length of the alkyl groups. Previously, n‐alkylsulfonylmethyl‐substituted polystyrenes with alkyl groups having more than 8 carbons (n > 8) showed homeotropic LC alignment behavior. Therefore, the additional phenoxy group in the side chain was found to improve the homeotropic LC aligning ability of the polystyrene derivatives.
Summary: A well defined blue electroluminescent fluorene‐carbazol‐fluorene trimer 3,6‐bis‐(9,9‐dihexyl‐9H‐fluoren‐3‐yl)‐9‐alkyl‐9H‐carbazole was synthesized using a Suzuki type cross coupling reaction as the key step. A way to attach this chromophore to a norbornene was developed and the resulting electroactive monomer was polymerised using the “3rd generation Grubbs catalyst” (N,N‐bis(mesityl) 4,5‐dihydroimidazol‐2‐ylidene)(3‐bromo‐pyridine)2(Cl)2Ru?CHPh), yielding an amorphous polymer with a narrow molecular weight distribution, which was used to build a light‐emitting diode exhibiting electroluminescence peaking at 410 nm.
Incorporation of the fluorene‐carbazol‐fluorene trimer as the emissive layer in an ITO/PEDOT:PSS/emitter/Ca/Al light emitting device. 相似文献
In this article, we present the results of a study of the preparation of a cyclohexene oxide (CHO) mid‐chain functional macromonomer via ATRP of styrene (St) and epoxidation on work‐up with 3‐chloroperoxybenzoic acid. The ATRP initiator, Br? CH? Br, was synthesized by the condensation of 3‐cyclohexene‐1,1‐dimethanol with 2‐bromopropanoyl bromide. The ATRP of St with Br? CH? Br and Cu(I)/bpy yielded well‐defined polystyrene with a cyclohexene mid‐chain group (PSt? CH? PSt). Epoxidation of the PSt? CH? PSt was performed using 3‐chloroperoxybenzoic acid. GPC, IR and 1H NMR analyses revealed that a low polydispersity macromonomer of polystyrene with CHO functionality at the mid‐chain (PSt? CHO? PSt) was obtained. The photoinduced cationic polymerization of PSt? CHO? PSt yielded comb‐shaped and graft copolymers.
