A new route to polyurethanes from ethylene carbonate, diamines and diols

A new method of the synthesis of aliphatic polyurethanes from diamines and diols or alternatively from α,ω-aminoalcohols using ethylene carbonate as a substitute of phosgene is presented. It has been found that the transurethanisation reaction between α,ω-bis(2-hydroxyethoxycarbonylamino)alkanes and diols containing six or more carbon atoms in a molecule carried out in the presence of tin coordination catalysts, leads to [n,m]polyurethane, and ethylene glycol formed as a side-product. In the case of using aminoalcohols, the reaction with ethylene carbonate leads to [n]polyurethanes. The polymerisation products were analysed by means of ¹H and ¹³C NMR spectroscopy, as well as MALDI-TOF mass spectrometry. The influence of the reaction conditions on the chemical structure of the reaction products and a plausible reaction mechanism are discussed.     

In situ FTIR study of the Cu electrode/ethylene carbonate + dimethyl carbonate solution interface

The interfacial phenomena between Cu electrode and solution of lithium perchlorate in ethylene carbonate (EC)-dimethyl carbonate (DMC) have been investigated using in situ reflection absorption Fourier transform infrared (FTIR) spectroscopy and single reflection ATR-FTIR spectroscopy. The ATR spectra confirmed the bands due to free EC and DMC and the molecules solvated to lithium ions in the solution. The bands due to the result of the interaction between ClO₄⁻ and DMC in the mixture solution also appeared in the ATR spectra. In the FTIR spectra, the potential dependence on the concentration of EC and DMC in the vicinity of the Cu electrode was observed. It was understood that the reversible changes in the concentration of free EC and DMC and solvated EC and DMC in the diffuse double layer take place with changing in potential. As the potential decreased, the free EC and DMC concentrations increased, while the concentration of the EC and DMC solvated to lithium ions decreased. Thus, it can be concluded that the equilibrium shifts from Li⁺(EC)₂(DMC)₂ to Li⁺(EC)₂(DMC) + DMC or Li⁺(EC)(DMC)₂ + EC as the potential decreases. The bands due to (CH₂OCO₂Li)₂ and CH₃OCO₂Li were observed for an irreversible reaction.     

Kinetics of dissociative adsorption of ethylene glycol on Pt(1 0 0) electrode surface in sulfuric acid solutions

The dissociative adsorption of ethylene glycol (EG) on Pt(1 0 0) electrode surface cooled in air after flame annealing was investigated by using programmed potential step technique and in situ FTIR spectroscopy. The stable adsorbates derived from EG dissociative adsorption on Pt(1 0 0) were determined by in situ FTIR spectroscopy as linear- and bridge-bonded CO. The quantitative results demonstrated that the average rate of dissociative adsorption of EG on Pt(1 0 0) surface varies with electrode potential, yielding a volcano-type distribution with a maximum value located near 0.10 V versus SCE. From the variation of the quantity of CO adsorbates generated in EG dissociative adsorption with the adsorption time t_ad, the initial rate (ν_i) of this surface reaction was evaluated quantitatively. The maximum value of ν_i has been determined to be 2.64 × 10⁻¹¹ mol cm⁻² s⁻¹ in a solution containing 2 × 10⁻³ mol L⁻¹ EG. The influence of the surface structure of Pt(1 0 0) electrode obtained by different pretreatment as well as of the specific adsorption of (bi)sulfate anions on the kinetics of EG dissociative adsorption has been also investigated and discussed. In comparison with a Pt(1 0 0) surface cooled in air atmosphere after flame treatment, the Pt(1 0 0) surface cooled in an Ar-H₂ stream or subjected to a treatment of fast potential cycling decreased significantly the initial rate ν_i of EG dissociative adsorption. Similar effect was also observed for the specific adsorption of (bi)sulfate anions. However, the maximum attainable coverage () of adsorbates derived from EG dissociative adsorption is not affected either by the surface structure of Pt(1 0 0) or by (bi)sulfate anions adsorption.     

On the use of vinylene carbonate (VC) as an additive to electrolyte solutions for Li-ion batteries

Vinylene carbonate (VC) was tested as an additive to electrolyte solutions for Li-ion batteries. For the model electrodes, synthetic graphite was chosen as the anode material, while LiMn₂O₄ spinel and LiNiO₂ were chosen as the cathode materials. The test solution was 1 M LiAsF₆ in a 1:1 mixture of ethylene and dimethyl carbonates (EC-DMC). Cyclic voltammetry (CV), chronopotentiometry, impedance spectroscopy, electrochemical quartz crystal microbalance (EQCM), FTIR and X-ray photoelectron spectroscopies have been used in this study. It was found that VC is a reactive additive that reacts on both the anode and the cathode surfaces. The influence of this additive on the behavior of Li-graphite anodes is very positive, since it improves their cyclability, especially at elevated temperatures, and reduces the irreversible capacity. The spectroscopic studies indicate that VC polymerizes on the lithiated graphite surfaces, thus forming poly alkyl Li-carbonate species that suppress both solvent and salt anion reduction. The presence of VC in solutions reduces the impedance of the LiMn₂O₄ and LiNiO₂ cathodes at room temperature. However, we have not yet found any pronounced impact of VC on the cycling behavior of the cathodes, either at room temperature or at elevated temperatures. Thus, VC can be considered as a desirable additive for the anode side in Li-ion batteries, one which has no adverse effect on the cathode side.     

Preparation and characterization of photocured thiol‐ene hydrogel: Adsorption of Au(III) ions from aqueous solutions

In this study, photocured a novel thiol‐ene hydrogels based on P(Penta3MP4/PEG‐DA/HEMA) were investigated for adsorption of Au(III) ions from aqueous solutions purposes. The photopolymerization kinetics of thiol‐ene‐based formulations was investigated by real‐time infrared spectroscopy. The chemical composition and surface morphology of hydrogels were also characterized. The effect of different parameters on Au(III) adsorption efficiency was examined in detail. Better adsorption behavior was achieved for Au(III) by P(Penta3MP4/PEG‐DA/HEMA) F1 hydrogels. The maximum uptake for Au(III) was at pH 0.5. Both Langmuir and Freundlich adsorption isotherm models were applied and the reusability of thiol‐ene hydrogels investigated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

HREELS investigations of trans-dichloroethene adsorption and chemical reaction on Cu(110)

The chemisorption and reaction of trans-dichloroethene on Cu(110) have been investigated by high-resolution electron-energy-loss spectroscopy (HREELS) as a function of coverage and temperature. At 135 K, both physisorbed and chemisorbed trans-dichloroethene are present. Heating to 200 K leads to the formation of acetylene and of a partially dehalogenated intermediate species. By 300 K, the acetylene trimerises to form adsorbed benzene at the surface. Adsorption of trans-dichloroethene at 300 K produces benzene directly. Evidence of C–Cl cleavage at temperature as low as 220 K is clearly marked by the emergence of very intense Cu–Cl stretching vibrations which remain even after further heating up to 570 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Electrochemical characteristics of phase-separated polymer electrolyte based on poly(vinylidene fluoride-co-hexafluoropropane) and ethylene carbonate

A polymer electrolyte based on microporous poly(vinylidene fluoride-co-hexafluoropropane) (PVdF-HFP) film was studied for use in lithium ion batteries. The microporous PVdF-HFP (Kynar 2801) matrix was prepared from a cast of homogeneous mixture of PVdF-HFP and solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). After evaporation of DMC and EMC, a sold film of the PVdF-HFP and the EC mixture was obtained. EC-rich phase started its formation in the PVdF-HFP/EC film at EC content of about 60 wt.% based on the total weight of PVdF-HFP and EC. The formation of the new phase resulted in the abrupt increase of the porosity of the PVdF-HFP matrix from 32 to 62%. The ionic conductivity of the film soaked in 1 M LiPF₆-EC/DMC=1/1 was significantly increased from order of 10⁻⁴ S/cm to order of 10⁻³ S/cm at the EC content of 60 wt.%. Thermal and spectroscopic investigations showed that most of the EC interact with PVdF-HFP with the EC content being below 60 wt.%. MCMB/polymer electrolyte/LiCoO₂ cells employing the microporous PVdF-HFP polymer film showed stable charging/discharging characteristics at 1C rate and good rate capability.     

碳酸二（4-甲基苯）酯合成及工艺研究

研究了三光气（BTC）与对甲酚反应合成碳酸二（4-甲基苯）酯的新方法,并对温度、酚钠盐浓度、三光气用量等因素进行考察。得到合成碳酸二（4-甲基苯）酯的优化工艺条件为温度26℃,酚钠盐浓度为2．90mol／L,n（三光气）：n（对甲酚）=1：0．51,收率96．4％,含量达98％以上。     

聚乙基醚碳酸酯二醇增韧环氧树脂

八成以羟基封端的脂肪族聚碳酸酯－聚惭基醚碳酸酯二醇（ＰＥＥＣＤ）,并用于环氧（ＥＰ）树脂的增韧。探讨了ＰＥＥＣＤ的相对分子质量、加入量等因素对增韧效果的影响。通过红外光谱分析、扫描电镜、差示扫描最热分析以及力学性能测试等方法研究了增韧ＥＰ的结构与性能的关系。     

Synthesis of oligocarbonate diols from ethylene carbonate and aliphatic diols catalyzed by alkali metal salts

The influence of alkali metal salt catalysts and reaction conditions on the oxyethylene units formation in the synthesis of oligocarbonate diols from five-membered cyclic carbonates and aliphatic diols is presented. The reaction mechanism, involving the alkoxide group formation from cyclic carbonate and alkali metal salts has been proposed and discussed. The oligomeric products were analyzed by means of MALDI-TOF mass spectrometry and NMR spectroscopy.     

Anion adsorption and atomic friction on Au(1 1 1)

The influence of anion adsorption on friction forces in an electrochemical environment has been studied by means of lateral force microscopy on Au(1 1 1) surfaces. Sensitivity to atomic stick-slip motion allows to reveal sulphate adsorption in ordered layers under the sliding tip at potentials lower than expected from cyclic voltammetry for the open surface. No ordered adsorption is found in lateral force measurements for the weakly adsorbed perchlorate anions. Correspondingly, some increase in friction in the anion adsorption regime is observed for sulphate but none for perchlorate adsorption. Friction increases significantly at the onset of oxidation in both sulphuric and perchloric acid solutions.     

Synthesis and characterization of polystyrene‐supported glucosamine resin and its adsorption behavior for Au(III)

A novel chelating resin, crosslinking polystyrene‐supported glucosamine (PS‐GA), was prepared and its structure was confirmed by FTIR, elemental analysis, and X‐ray photoelectron spectroscopy. The adsorption properties of PS‐GA for Au(III) were investigated. PS‐GA resin possessed excellent enriching property to Au(III) ions and adsorption proportion E% could reach to about 90 shortly after 3 h. The adsorption dynamics of Au(III) showed that the adsorption was controlled by liquid film diffusion and the apparent activation energy E_a was 12.91 kJ mol^?1. Both Langmuir model and Freundlich model could describe the isothermal process of Au(III), and ΔG, ΔH, ΔS values were calculated. The mechanism of adsorption for Au(III) was confirmed by FTIR, SEM, and XPS. The results showed that redox reaction occurred and both coordination and ion‐exchange existed simultaneously in the adsorption. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4581–4586, 2006     

In situ FTIRS and EQCM studies of glycine adsorption and oxidation on Au(1 1 1) electrode in alkaline solutions

Dissociative adsorption and oxidation of glycine on Au(1 1 1) single crystal electrodes in alkaline solutions were studied in the present paper using cyclic voltammetry (CV), in situ FTIR spectroscopy (FTIRS) and electrochemical quartz crystal microbalance (EQCM). In situ FTIRS results demonstrated that adsorbates derived from glycine dissociative adsorption are adsorbed cyanide anions (CN_ad⁻). The CN_ad⁻ species are stable on Au(1 1 1) surface in the potential region from −0.8 to 0.0 V, and can be oxidized when electrode potential is increased above 0.1 V. The oxidation of CN_ad⁻ releases surface active sites for further glycine oxidation. The products of CN_ad⁻ oxidation were determined by in situ FTIRS as cyanate (OCN⁻), aurous cyanide (AuCN) and aurous di-cyanide (Au(CN)₂⁻). The formation of Au(CN)₂⁻ may initiate a dissolution of Au(1 1 1) surface atoms, which has been confirmed by a loss of surface mass determined in EQCM studies. It has revealed also that at high electrode potential region glycine may be split on Au(1 1 1) surface to form AuCH₂NH₂ and AuCOO⁻ adsorbates. Further oxidation of these species yielded CO₂ and -NH₂, and the AuCH₂NH₂ may be also combined with surface Au oxide to form methylamine. The CO₂ species produced in glycine oxidation are all retained in alkaline solutions to generate carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) species that were clearly determined by in situ FTIRS studies.     

The surface modification of magnetic poly(methyl acrylate) microspheres with dendron and application in Au(III) adsorption

An improved suspension polymerization method for preparation of the magnetic poly(methyl acrylate) microspheres (mPMA‐DVB) was investigated. Through subsequent reaction with methyl acrylate (MA) and ethylenediamine (EDA), the magnetic poly(methyl acrylate) microspheres with dendron surface was obtained, and the magnetic poly(methyl acrylate) microspheres with dendron surface reacted with carbon bisulfide and sodium hydroxide to create sodium dithiocarbamate. Following, the resultant magnetic microspheres with dendron surface modification were used to adsorb Au(III) from aqueous solution. The result showed that the capacity of amino groups on the surface of the mPMA microspheres increased from 1.67 mmol/g for the magnetic polymer microspheres with G₀ dendron to 4.35 mmol/g with G₃ dendron, and the adsorption capacity rose from 0.1981 g/g with G₀ dendron to 0.7853 g/g with G₃ dendron. The effects of solution pH, the adsorption temperature, the adsorption time, and the initial concentration of Au(III) on the adsorption of Au(III) were studied, the optimum pH for Au(III) adsorption was found at pH = 1, the adsorption capacity achieved the maximum in 60 min, and the adsorption process was endothermic reaction and conformed to pseudo‐second‐order kinetic models. Furthermore, the adsorption process was in accordance with the Langmuir model. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Inhibition of potential-induced surface reconstruction on Au(1 0 0) electrode by the products of tyramine electro-oxidation

Our studies are focused on the stability of the unreconstructed Au(1 0 0) surface against potential-induced reconstruction in a solution containing products of tyramine (T) electro-oxidation. It is demonstrated by cyclic voltammetry and capacity measurements that in the presence of T, which reduces the stability of the reconstructed Au(1 0 0) surface, the potential-induced surface reconstruction is a fast process on condition that a preceding positive going scan is performed to potentials from the double layer region. Further extension of this scans to the potential region where the oxidation of T takes place, causes a considerable slow down of the potential-induced reconstruction. Kinetics of the potential-induced reconstruction in a solution containing products of T electro-oxidation is investigated. Inhibition of this process is explained by a strong adsorption of species produced during T oxidation on the gold surface.     

磁场对碳酸钙析晶过程影响的定量研究

借助析晶动力学监测系统，研究了一定强度的磁场对碳酸钙过饱和溶液的析晶过程的影响。定量的、可重复的数据表明，在一定的Ca^2 和CO3^2－浓度范围内，磁场对碳酸钙晶体的生长析出具有明显的抑制作用。对不同溶液进行磁处理的实验结果显示，磁场阻垢既通过成垢阳离子Ca^2 起作用，也通过成垢阴离子CO3^2-起作用。     

Thermodynamic and column studies of Au(I) adsorption on weak alkaline anion exchange fibre from cyanide leaching solution

A novel method of adsorption of Au(I) from cyanide leaching solution with weak alkaline anion exchange fibre (WAAEF) was studied here. The thermodynamics of Au(I) from cyanide leaching solution by the WAAEF from 288 K to 308K have been investigated. Langmuir, Freundlich and Temkin models were adopted and the results confirmed that the Freundlich model fitted best with the equilibrium data. Thermodynamic calculation indicated that the absorption of Au(I) from cyanide leaching solution by WAAEF was an endothermic process with increased entropy. In the dynamic adsorption process, the optimal operational conditions, i.e. flow rate 670.0 BV?h^?1, loading density 0.211 g?cm^?3 and pH value 8.89 of the original solution, were obtained. Dynamic analytical analysis depicted that the elution yield could exceed up to 97% using a mixture of 3% H₂SO₄ and 8% (NH₂)₂CS solution at a flow rate of 100.5 BV?h^?1.     

Efficient removal of cationic dyes from aqueous solutions using a modified poly(ethylene terephthalate) fibers adsorbent

ABSTRACT

A novel adsorbent was synthesized through functionalization of glycidyl methacrylate-g-poly(ethylene terephthalate) (GMA-g-PET) fibers with iminodiacetic acid (IDA) to give IDA-GMA-g-PET fibers. This adsorbent was then exploited for the removal of Malachite Green (MG) and Rhodamine B (RB) dyes. MG has shown faster adsorption kinetics and equilibrium was attained in 15 mins. and 90 mins. for MG and RB, respectively. IDA-GMA-g-PET fibers showed 100% removal efficiency for MG and RB dyes from the solutions having initial concentrations of 300 mg L^?1and 200 mg L^?1, respectively. Desorption conditions of dyes and reusability of the fibers were also investigated.     

Development and characterisation of a novel composite electrode material consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles

Composite material consisting of poly(3,4-ethylenedioxythiophene) (PEDOT), including Au nanoparticles encapsulated by N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulphonate (SB12) is synthesised by constant-current method on ITO glass, in aqueous medium, leading to an electrode coating. The synthesis process is followed by UV-vis spectroelectrochemistry, both in normal-beam and in parallel-beam configurations. Under the same experimental conditions PEDOT is also synthesised by electropolymerisation only in the presence of LiClO₄ supporting electrolyte, as well in solutions also containing SB12. The data relative to the electrosynthesis of the three materials are compared. The composite material based on the conductive polymer matrix including Au nanoparticles has been characterised by SEM, TEM, ICP, Raman and UV-vis spectroscopies. The behaviour of the three different electrode coatings with respect to p-doping process has been studied by conventional electrochemical techniques and by potentiostatic and potentiodynamic UV-vis spectroelectrochemical methods. Conclusions are drawn out about the effect of the presence of the surfactant and of Au nanoparticles on the electrochemical properties of the electrode system.     

Preparation of Au/TiO2 catalysts from Au(I)–thiosulfate complex and study of their photocatalytic activity for the degradation of methyl orange

Gold loaded on TiO₂ (Au/TiO₂) catalysts were prepared using Au(I)–thiosulfate complex (Au(S₂O₃)₂³⁻) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S₂O₃)₂³⁻ as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO₂. The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO₂ catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S₂O₃)₂³⁻ precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO₂ catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO₂ and further affects the photocatalytic activity of the obtained catalysts.