Comparison of photovoltaic devices based on MEH-PPV with various molecular weights

Theneedforefficient,inexpensiveandrenewableenergysourcesisstimulatingnewapproachestothepro-ductionoflow-costphotovoltaicdevices.Althoughinor-ganicsemiconductorsaretheprimaryproductions,highfabricationcostsmakeinorganicsolarcelldifficulttomeetlarge-scaleapplicationsduetoitscomplicatedtech-nology,highcostandrigormaterialprocessing.Thesolarcellsbasedonorganicmolecule[1]andconjugatedpoly-mer[2—6]havealreadywelldeveloped.Conjugatedpolymerphotovoltaicdeviceshaveattractedagreatdealofatten-tionduetot…     

Excited-state solvation dynamics of meso-tetrakis(4-sulfonatophenyl) porphyrin in solid imidazolium-sulfonate-based ionic liquids

The steady-state absorption and fluorescence emission positions of diprotonated meso-tetrakis(4-sulfonatophenyl) porphyrin (H₄TPPS^2?) are dependent on the polarity of the selected two solid ionic liquids (ILs) and are red-shifted with the increase of cation size. The solvation dynamics process of H₄TPPS^2? in these ILs occurs on two well-separated time scales. The short components with 121.2–128.6 ps arise from the local motion of the ion-pairs in close proximity to the porphine core, and the long components with 1056.6–1261.8 ps are due to the collective translation motions of the ion-pairs. The dynamic Stokes shifts and the relaxation times increase with the increasing cation size of the ILs.     

Electron transfer in N-butylpyridinium tetrafluoroborate ionic liquid by pulse radiolysis

The radiolysis behavior of neat pyridinium ionic liquids (ILs) and their aqueous solutions was investigated using nanosecond pulse radiolysis techniques. Radiolysis of the ionic liquids, such as N-butylpyridinium tetrafluoroborate (BuPyBF4 ), resulted in the formation of solvated electrons and organic radicals. Solvated electrons reacted with the pyridinium moiety to produce a pyridinyl radical, which can transfer electrons to various acceptors. The electron-transfer rate constants of the solvent-derived butylpyridinyl radicals in BuPyBF 4 and in several compounds (for example, duroquinone, 4,4′-pyridine, benzophenone, and 1,1′- dimethyl-4,4′-bypyridinium dichloride) (k of the order 10 8 L/(mol s) were lower than those measured in water and in i-PrOH but were significantly higher than the diffusion-controlled rate constants estimated based on viscosity. The electron-transfer rate constants in neat BuPyBF 4 were one order of magnitude faster than the diffusion-controlled values. This finding suggests that Bu- PyBF 4 acts not only as solvent but also as active solute, such as in solvent-mediated reactions. These reactions result in electrons reaching their final destinations via intervening pyridinium groups without requiring the diffusion of a specific radical.     

Synthesis of poly(glycolide-CO-2-hydro-2-oxo-1,3,2-dioxaphosphorinane)

A novel polyester containing glycolic acid (GA) and 2-hydro-2-oxo-1,3,2-dioxaphosphorinane (TMP) was prepared by ring-opening polymerization. The composition and the structure of the titled polymer were investigated by¹H NMR,¹³C NMR, FT-IR, EA, and VPO. The influence of time on total conversion and molecular weight was also studied. Fan Changlie: born in 1939, Professer     

Synthesis, structure and ethylene polymerization behavior of titanium complexes [C3H6（N = CH-Ar-O）2]TiCl2

Early transition metal catalysts containing twophenoxy-imine ligands, called FI catalysts which havevery high potential to become a new generation of olefinpolymerization catalysts, are new-type catalysts whichhave attracted much attention in recent years[1—3]. Many ofthem display activities comparable to those of the metal-locene catalysts and, in some cases, behave as living po-lymerization catalysts of α-olefins. Brookhart and Gibsonet al.[4,5] recently reported separately series of Schi…     

Synthesis and characterization of amphiphilc block copolymer poly(methyl acrylic acid)-block-polytetrahydrofuran

Under the specially designated condition the polymerization of both tetrahydrofuran (THF) andtert-butyl methacrylate (tBMA) is a living one. The diblock copolymer, poly(tert-butyl methacrylate)-block-polytetrahydrofuran (PtBMA-b-PTHF), was successfully synthesized by means of the coupling reaction of living cationic PTHF⁺, SbF₆ with living anionic PtBMA^-, Li⁺. LiCI, which has a beneficial effect on the molecular weight distribution (MWD) in the anionic polymerization of (meth)acrylates, hinders the coupling reaction of living chains and cannot be used in the preparation of tBMA precursor. The hydrolysis of the aforementioned diblock copolymer under acid condition results in the amphiphilic diblock copolymer, i.e. poly(methy1 acrylic acid)-block-polytetrahydrofuran (PMAA-b-PTHF). The diblock copolymers were characterized with GPC and IR.     

Solid-phase preparation and characterization of Chitosan

0　IntroductionChitosanhasbeenwidelyusedinpharmaceu tical,agriculturalandindustrialfieldbe causeofitsintriguing properties[1 ] .Chemicalmethodstopreparechitosanfromchitinhavebeenbroadlystudiedincludingsolutionmethod ,meltedalkalinemethod,microwavesemi drymethod ,improvedLinelbergmethod ,dissolution precipita tionmethodandsoon ,inwhichalkalinewasallusedasthecatalyst[2 ] .Biologicalmethodwasapromisingwayinthatitproducedlittleenviron mentalpollutionanditsreactionconditionsweremild .However,thism…     

The syntheses and properties of poly(L-lactide)

Poly (L-lactide) was prepared by bulk polymerization ofL-lactide at 140°C in the presence of stannous octoate. The polymer products were characterized by number average molecular weight Mn, weight average molecular weight Mw and molecular weight distribution MWD (M _w/M _n) respectively. The results showed that stannous octoate was a high effective catalyst, and coordinated insertion mechanism of the reaction was proposed. Foundation itemL Supported by the key Project of the Ministry of Science and Technology (96-920-21) Biography: Chen lian-xi (1964-), male, Associate Professor, research direction: organic and polymeric materials.     

微波辅助合成聚天冬氨酸

借助微波辅助手段,以天冬氨酸（A）为原料,在均三甲苯和环丁砜混合溶剂中,以磷酸（体积分数为85%）为催化剂进行聚合反应。考察了催化剂用量、微波功率、反应温度和反应时间等因素对聚琥珀酰亚胺（PSI）的产率以及分子量的影响;进一步对PSI进行水解反应,并用红外光谱对水解产物进行结构表征。结果表明：借助微波辅助加热手段,使得聚合反应时间大大缩短,由传统热缩合反应的3～5h缩短为20min左右,反应效率明显提高;随催化剂用量的增加,PSI的产率增加,分子量降低,但过多的催化剂存在会导致产率下降;微波功率增大,PSI产率与分子量均呈下降趋势;在微波作用下,聚合反应温度（170～200℃）明显低于传统热缩合聚合的温度,并随着温度的升高和反应时间的延长,PSI的产率和聚天冬氨酸（PASP）分子量均呈现明显增加。在合适的条件下,可制备出数均分子量为6000～20000,分子量分布为1.3～2.4的PASP产物。     

特种工程塑料聚芳醚酮的研究进展

阐述了聚芳醚酮的基本性质、合成方法及新型结构聚芳醚酮的设计及研究进展，并指出了聚芳醚酮的应用前景。     

Synthesis and property of imidazolium oxidative-thermoregulated ionic liquids

A series of novel imidazolium oxidative-ther- moregulated bifunctional ionic liquids （ILs） have been synthesized by introducing the thermoregulated structural unit into imidazolium cation and using heteropolyanion as the anion of ILs. The structures of these new type of taskspecific ionic liquids （TSILs） are characterized by FT-IR and 1H NMR. The thermostability of ILs is analyzed by thermogravimetry. The thermoregulated properties of ILs in aqueous and organic solvents are mainly investigated. These ILs have the corresponding cloud points （CPs） in aqueous. The effects of IL concentration, polymerization degree, inorganic additives and organic additives on the CP are studied. IL/DMF/n-heptane or n-octane biphasic system has the corresponding critical solution temperature （CST）, and has the feature of ＂homogeneous at high temperature, heterogeneous at low temperature＂. The effects of IL dosage and polymerization degree on the CST are given. IL/DMF/n-octane thermoregulated biphasic system has been successfully applied for catalytic oxidative desulfurization of model fuels. This study opens up a new way for catalytic oxidation to achieve an integration of homogeneous catalysis and heterogeneous separation.     

Characterization of chromophoric organic matter in effluent from Vitamin C wastewater anaerobic-aerobic treatment

Chroma is not effectively removed from Vitamin C (VC) wastewater by traditional anaerobic-aerobic treatment. This means current treatment does not meet the strict new discharge standard for VC wastewater in China. However, to date, no studies have investigated the removal of chroma from VC wastewater, or characterized the chromophoric organic matter in wastewater. In this study, choromophoric organic matter in effluent from anaerobic-aerobic treatment of Vitamin C wastewater was characterized using high performance gel permeation chromatography (HPGPC), ultrafiltration, and infrared (IR) and ultraviolet-visible (UV/Vis) spectroscopy. Routine water-quality indices were determined, and indicated that the organic matter in the effluent contained nitrogen. The molecular weight of most organic matter in this effluent was below 1000 Da, while the remainder was between 1000–3000 Da. These compounds are likely biodegradation products of high molecular weight organic matter in the effluent, which are raw materials and byproducts from VC production. IR spectra indicated that the low molecular weight (<1000 Da) organic matter and higher molecular weight (1000–3000 Da) organic matter contain similar major functional groups, including -OH, -NH₂, -CO-NH₂, -C=O-, and -COO⁻. The effluent was treated using electrolysis, and UV/Vis spectra of this effluent before and after electrolysis indicated that -C=O is an important chroma group in this effluent. Electrolysis can easily break -C=O, and provides a feasible technology for the advanced treatment of anaerobic-aerobic effluent from VC wastewater treatment.     

反相悬浮聚合法合成超高分子量聚丙烯酸钠

以丙烯酸钠和丙烯酰胺为单体,采用反相悬浮聚合法制备了超高分子量的聚丙烯酸钠(NaPA).研究了引发剂浓度、抗交联剂及其他助剂对合成产物聚丙烯酸钠性能的影响.结果表明,(NH4)2S2O8的最佳用量是0.15%(质量分数);随着CO(NH2)2用量的增加分子量提高明显;在聚合体系中加入甲基丙烯酸N,N-二甲氨基乙酯(DMAEMA)可提高分子量但用量应控制在9.4×10-4%～15.6×10-4%之间.同时用抗交联剂防止交联反应,结合使用醋酸钠和异丙醇这两种分子量调节剂不仅能提高分子量而且溶解性也得到改善.最终得到了分子量高达3.0×107的产物,其分子量和溶解性能较前人研究成果有明显提高.     

己二酰双己内酰胺扩链合成聚己二酸丁二醇酯

以己二酰双己内酰胺(ABC)作为扩链剂，对低相对分子质量的聚己二酸丁二醇酯(PBA)进行扩链，研究了各种因素对聚酯相对分子质量的影响; 并采用¹H-NMR和红外光谱对扩链后聚酯的结构进行了表征，提出了扩链反应的机理。扩链剂己二酰双己内酰胺与端羟 基PBA进行扩链反应时,主要通过脱除己内酰胺，以己二酰结构将PBA预聚体偶联起来，使聚酯的相对分子质量成倍增加。     

Effect of molecular weight and structure on antitumor activity of oxidized chitosan

Various low molecular weight chitosans were prepared by oxidative degradation with H₂O₂, and characterized by IR,¹³C-NMR and gel permeation chromatography. Their carboxylic contents increased with decrease in molecular weight (M _w ). The antitumor test of the samples against sarcoma 180 tumors suggested that the water-soluble chitosan with higherM _w have higher inhibitory ratioin vivo. The introduction of carboxylic group is advantage to water-solubility of chitosan, but more acidic groups might decrease the function of amino groups of chitosan against sarcoma 180 tumor. Foundation item: Supported by the National Natural Science Foundation of China (No. 29977014) Biography: Qin Cai-qin (1965-), male, Ph. D candidate, Associate professor, research direction: biopolymers.     

HSO3-functionalized Brønsted acidic ionic liquids promote esterification of aromatic acid

Esterification of aromatic acid can be promoted via HSO3-functionalized Br nsted acidic ionic liquids (ILs). Under the optimum conditions, using 1-(3-sulfonic acid) propyl-3-methylimidazolium hydrogen sulfate ([MimC3SO3H][HSO4]) and 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate ([MimC 4 SO 3 H][HSO4 ]) as dual solvent-catalysts, the conversion of esterification of aromatic acid was determined to be more than 90%, indicating that HSO3-functionalized ILs show much better catalytic ability than those of non-functionalized ionic liquids. The separation of desired product was easily performed by extraction with diethyl ether and these HSO3-functionalized ILs could be reused 7 times after vacuum drying. Our data represent an environmentally friendly method for the preparation of aromatic esters.     

Half-sandwich β-diketonato complexes of zirconium and their application as catalysts to ethylene polymerization

The bis(β-diketonato) Zr complexes CpZr(acac)2Cl (acac = acetylacetonato) (1) and Cp*Zr(acac)2Cl (2) can be synthesized by the reac-tion of Cp′ZrCl3(Cp′ = Cp or Cp*) with 2 equiv of lith-ium acetylacetonate. CpZr(acac)2Cl (1) can be quan-titatively prepared by treatment of Cp2ZrCl2 with ex-cess acetylacetone. The tris(β-diketonato) Zr com-plex CpZr(tfac)3 (tfac = trisfluoroacetylacetonato) (3) has been prepared by treatment of CpZrCl3 with so-dium trisfluoroacetylacetonate. The replacement of both chlorine atoms and one Cp group from zir-conocene dichloride by nonfluorinated diketone,acetylacetone,readily occurs at room temperature in triethylamine medium,offering the tris(β-diketonato) Zr complex CpZr(acac)3 (4). The complexes were characterized by 1H NMR spectroscopic methods. In addition,the molecular structures of complexes 3 and 4 have been determined by X-ray diffraction methods. When activated by excess methylaluminoxane (MAO),these complexes were active for ethylene polymerization,offering polyethylenes with high mo-lecular weights and narrow molecular weight distribu-tions. Complex 4 showed a very high ethylene po-lymerization activity of up to 7100 kg PE/mol Zr·h at 5 atm. Complexes 1 and 2 were also active for ethyl-ene/1-hexene copolymerization.     

Kinetic study of the reaction of chlorine atoms with 3-methyl-3-buten-1-ol

The reaction of a typical unsaturated alcohol, 3-methyl-3-buten-1-ol （MBO331）, with Cl atoms, was investigated for the first time. The reaction was investigated using discharged flow-tube coupled with electron impact mass spectrometer. The experiments were performed over the temperature range of 248 K-298 K and at pressure of 1 torr in He as the bath gas. The obtained kinetic data were used to derive the Arrhenius expression： k1 = （3.47 ± 1.21） × 10^-11 exp[（ 599 ±69）/7] cm^3 molecule^-1 s^-1. Finally, atmospheric lifetimes of the MBO331 with respect to OH radicals, NO3 radicals and CI atoms have been calculated and the atmospheric implications are considered briefly.     

The impact of HS radicals on the measured rate constant of H<Subscript>2</Subscript>S with OH radicals

The rate constant for the reaction of OH radicals and hydrogen sulfide (H₂S) was studied in different bath gases (including N₂, air, O₂ and He) by using relative technique at 298 K. The small difference of the measured rate constants between N₂ and those with the presence of O₂ suggested possible influence of HS self reaction. Further experiments with NO_x presence for scavenging HS demonstrated this assumption. The rate constant of (5.48±0.12) ×10^–12 cm³ molecule^–1 s^–1 obtained with 4.09 ×10^–4 mol m₃ NO presence may be accurate for estimating the atmospheric lifetime of H2S. The results provided circumstantial evidence that the rapid reaction of HS with N₂O is suspected.     

Atom Transfer Radical Polymerization of Acrylonitrile in Ionic Liquids

The controllable molecular weight and polydispersity of polyacrylonitriles(PANs) were synthesized in ionic liquids(ILs) by atom transfer radical polymerization(ATRP) using ethyl-2 bromopropionate(EPN-Br) as initiator and CuBr/pentamethyldiethylenetria-mine(PMDETA) as catalyst.The polydispersity index(PDI) in the ATRP of acrylonitriel(AN) in ILs is lower than 1.3.From the polymerization kinetics,plots of ln([M]0/[M]) with time show a linear dependence at the early stage of polymerization while the deviation ...