Table of Content

24 October 2004, Volume 25 Issue 10

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Articles

Effect of Lanthanides on the Interaction Between Recombinant Endostatin and Heparin

WANG Qun, NI Jia-Zuan,

2004, 25(10):  1783-1788. 

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The interaction of recombinant endostatin with lanthanides and heparin was studied by fluorescence and CD spectra. The results indicate that the binding of lanthanides, heparin to recombinant endostatin(rhES) causes quenching of its fluorescence and conformational changes of rhES.The binding of lanthanides to rhES can affect the interaction between its protein and heparin and decrease the inhibiting activity of rhES to the proliferation of human umbilical vein endothelial cell.

Preparation of Phosphors M₂B₄O₇:Eu³⁺(M=Na, K) in Ambient Air and Their Property Characterization

LIU Xiao-Tang, SHI Chun-Shan, XIE De-Min, ZHUANG Guo-Xiong, LIANG Hui-Ying, YANG Dan

2004, 25(10):  1789-1792. 

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M₂B₄O₇:Eu³⁺(M=Na, K) phosphors were synthesized by solid state reaction in ambient air. The optimum preparing conditions were studied and phase analyses were carried out by using powder XRD method. The structure of the borates contains both [BO₃] and [BO₄] coordination polyhedra. The luminescent properties of M₂B₄O₇:Eu³⁺ under ultraviolet light excitation were studied. The results show that the predominant emission of Eu³⁺ is ⁵D₀- ⁷F₂ transition, demonstrating that the rare earth ions occupy the non-centrosymmetrical sites in M₂B₄O₇ and Eu³⁺ ion can be stable in the matrix. The intensity of emission of Na₂B₄O₇:Eu³⁺ is stronger than that of K₂B₄O₇:Eu³⁺ when the doped Eu³⁺ concentration is the same.

DC Conductivity of Au Nanoparticles in Organic Solvent

FANG Fang, WANG Ying, ZHANG Xiao-Yan, ZHANG Ya-Fei

2004, 25(10):  1793-1795. 

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Gold nanoparticles were chemically synthesized with a diameter of about 10 nm. Dodecanethiol, tetradecanethiol and hexadecanethiol were used to protect Au nanoparticles. Then Au nanoparticles/chloroform and Au nanoparticles/toluene suspensions were prepared. DC conductivity of different suspensions was investigated. The electrical conductivity of the samples increased with the increase of the concentration of Au nanoparticles, and a rapid increase in conductivity is observed when the concentration increased from a low value to a moderate value. The conductivity increases slowly when the concentration is larger than the moderate value. The moderate concentration values are₁1.22, 7.96 and 5.47 g/L in chloroform suspensions when Au nanoparticles were encapsulated by dodecanethiol, tetradecanethiol and hexadecanethiol, respectively. The conductivity for Au nanoparticles/chloroform suspension is higher than that for Au nanoparticles/toluene suspension in the whole concentration range.

Synthesis and Properties of Nanoparticle Al₂O₃ Modified by Organic Ligand

XIA Jiang-Bin, YANG Hong, LI Fu-You, HUANG Chun-Hui,

2004, 25(10):  1796-1798. 

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A novel β-diketone ligand 3-methyl-phenyl-4-octadecyl-5-pyrazolone(PMOP) and nanoparticle Al₂O₃ modified by the ligand PMOP were synthesized and characterized by infrared spectroscopy, UV-Vis spectroscopy, ¹H NMR and photoluminescence spectroscopy. The modified nanoparticle Al₂O₃ with good photoluminescence property can dissolve in the organic solvent such as chloroform, ethanol, and toluene and so on, which indicates that inorganic nanoparticle modified by organic ligand can show some new photophysical properties. Moreover, the modified nanoparticle Al₂O₃ can be used as a sustain material and applied to dye sensitized nanocrystal solar cell.

Supramolecular Assembly of Methyl Orange-pillared Hydrotalcite and Its Light and Thermal Stability

ZHANG Wei-Feng, LI Dian-Qing, SUN Meng, Evans D. G., DUAN Xue

2004, 25(10):  1799-1803. 

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Methyl orange is one of acid dyes, but its range of use is greatly limited because of its low light and thermal stability. Methyl orange anion-pillared hydrotalcites were successfully assembled by an ion exchange method using Mg_0.67Al_0.33(OH)₂(CO₃)_0.165·0.58H₂O as a precursor. The sample thereby obtained was characterized by XRD, FTIR and UV-Vis spectroscopies and TG-DTA. The results show that the original interlayer carbonate anions of the hydrotalcite precursor can be completely replaced by methyl orange anions. The structure of the methyl orange anion-pillared hydrotalcite was investigated. It was found that the interaction of the host layers and the guests is through electrostatic attraction, hydrogen bonding and other weak chemical bonding interactions, confirming that the intercalated hydrotalcite has a supramolecular structure. The light and thermal stability of methyl orange anion-pillared hydrotalcite was enhanced to a considerable extent, comparing with that of methyl orange.

Syntheses, Crystal Structures and Fluorescences of Two Novel 2D Cd(Ⅱ) Coordination Polymers

NIU Shu-Yun, CHI Yu-Xian, JIN Jing, YANG Guang-Di, YE Ling

2004, 25(10):  1804-1806. 

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Two novel Cd(Ⅱ) coordination polymers, [Cd₂(C₁₀H₂O₈)\5(H₂O)₆]_n (1) and [Cd₄(C₆H₄O₂N)₈(H₂O)₄]_n (2) (C₁₀H₂O₈=1,2,4,5-benzenetetracarboxyl and C₆H₄O₂N=nicotinato), were hydrothermally synthesized and characterized by X-ray diffraction of the single-crystal and fluorescence spectra. Complex 1 crystallizes in triclinic system, space group P1 with a=0.559 62(7) nm, b=0.777 58(6) nm, c=0.969 75(10) nm, α=111.981(5)°, β=101.649(6)°, γ=98.240(5)°, and Z=1. Final R=0.024 8(wR=0.078 5). Complex 2 belongs to orthorhombic system, space group Pbca with unit cell dimensions a=1.144 94(19) nm, b=1.209 69(6) nm, c=1.740 73(8) nm and Z=8. Final R=0.018 5(wR=0.034 8). Both the two complexes are coordination polymers with a two-dimensional infinite structure, the repeat unit is [Cd₂(C₁₀H₂O₈)(H₂O)₆] (1) and [Cd₄(C₆H₄O₂N)₈(H₂O)₄] (2) which are bridged by the ligands of 1,2,4,5-benzenetetracarboxyl(C₁₀H₂O₈) and nicotinato(NA), respectively. The two polymers show strong fluorescence with λ_em=433 nm(λ_ex=333 nm, 1) and λ_em=423 nm(λ_ex=330 nm, 2) in the solid state at room temperature. The emissions observed in the polymers are tentatively assigned to the ligands fluorescence(LLCT).

Synthesis and Structure of a Novel Microporous Coordination Polymer [Co₂(Hisor)₂(4,4′-bpy)₂(H₂O)₂]·4,4′-bpy Constructed by Hydrogen Bonds

SUN Chang-Yan, JIN Lin-Pei

2004, 25(10):  1807-1809. 

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A novel microporous coordination polymer [Co₂(Hisor)₂(4,4′-bpy)₂(H₂O)₂]·4,4′-bpy was synthesized by hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analysis and IR spectrum. The crystal belongs to the monoclinic system and space group is P2/n with a=1.040 6(3) nm, b=1.138 8(4) nm, c=1.854 7(6) nm, β=102.991(6)°, V= 2.141 6(12) nm³, Z=2, D_c=1.443 Mg/m³, M_r=930.62, μ=0.842 mm^-1, F(000)=952, GOF= 1.072, R=0.065 4, wR=0.146 8[I>2σ(I)]. There are two crystallographically independent Co(Ⅱ) ions in the title complex. The Hisor^2- and 4,4′-bpy link the metal ions into 2D grids with dimension of 0.522 3 nm×1.138 8 nm. There are O—H…O and N—H…O hydrogen bonds in the complex resulting in the formation of 3D network with 1D channels, in which are free 4,4′-bpy molecules.

Synthesis and Crystal Structure of Supramolecular Alkaline Metal Phosphonate Sodium Piperazinyldiphosphonate

HUANG Kun-Lin, YU Ji-Hong, LI Cai-Jin, LI Guang-Hua, WANG Guang-Mei, XU Ru-Ren

2004, 25(10):  1810-1812. 

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A novel supramolecular sodium N,N-piperazinebis(methylenephosphonate) Na₂[(HO₃PCH₂)·NC₄H₈N(CH₂PO₃H)](H₂O)₈·2H₂O, self-assembled into infinite₁D chains, was synthesized by the reaction of N,N-piperazine bis(methylenephosphonic acid) with NaOH. Its structure was characterized by single crystal X-ray diffraction, ICP and elemental analysis. The compound crystallizes in triclinic system, space group P1 with a=0.659 06(2) nm, b=0.726 73(2) nm, c= 1.158 25(4) nm, α=79.751(2)°, β=75.833(2)°, γ=74.122(2)°, V=0.513 68(3) nm³, Z=2, D_c=1.611 Mg/m³, μ=0.331 mm^-1, F(000)=264, S=1.098, R₁=0.045 2, wR=0.136 0. In the crystal, edge sharing octahedron Na₂O₁₀ dimers and tetrahedron PO₃C are assembled to an 1D chain via the bridges of heterocycle. 3D supramolecular framework is self-assembled from 1D chains through H-bonds.

Hydrothermal Synthesis and Characterizations of Na₆In₄[P₇O₂₄(OH)₅]·4H₂O

MAO Shao-Yu, LI Man-Rong, CHEN Hao-Hong, HUANG Ya-Xi, MI Jin-Xiao, ZHAO Jing-Tai

2004, 25(10):  1813-1815. 

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A new sodium indium phosphate Na₆In₄[P₇O₂4(OH)₅]·4H₂O was synthesized under a mild hydrothermal condition and its structure was determined by means of single-crystal X-ray diffraction methods. The title compound crystallizes in a hexagonal system, space group P6₃, with a= 0.950 23(5) nm, b=0.950 23(5) nm, c=1.694 2(2) nm, α=90°, β=90°, γ=120°, V=1.324 8(2) nm³, Z=8, structure refined to R=0.052 8 and wR=0.116 5 for₂ 134 independent observed reflections. The three-dimensional network structure consists of helical chains formed by apex-sharing polyhedra. The connection of the chains results in 4- and 8-polyhedral rings and cages centered by three indium metal connecting oxygen atoms formed by three 4-rings. The three-connected oxygen atom is firstly observed in indium phosphate systems.

Studies on the Method of Flow Cytometry Integrated with Microfluidic Chip

YANG Rui, MU Ying, ZOU Ming-Qiang, WU Zhe, JIN Qin-Han

2004, 25(10):  1816-1819. 

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A microfluidic chip is designed and fabricated, and coupled with flow cytometry. By using Na₂HPO₄ solution added with hydroxypropyl methyl cellulose(HPMC) as buffer and sheathing fluid, the problems met with the flowing of microspheres in the microchannel were solved, and the fluidic conditions were under more effective control. By using a home-made laser induced fluorescence system and electrokinetic focusing, the counting of the microspheres and real time observation of their actual fluidic state through an inverted fluorescence microscope is made. The whole system is compact and easy to be operated. The comsumption of reagent and sample is little and the speed of the assay is quick.

A Biosensor for Hydrogen Peroxide Based on Peroxidase Immobilized by Plasma Polymerized Film

LIU Bing, YANG Ming-Hui, YANG Hai-Feng, SHEN Guo-Li, YU Ru-Qin

2004, 25(10):  1820-1824. 

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A biosensor for hydrogen peroxide assay based on glassy-carbon electrode with plasma polymerized polyethylene diamine film was proposed. Plasma polymerization technique was utilized to make amino groups deposit on the surface of glassy-carbon electrode for an oriented covalent attachment of HRP. The conditions of plasma polymerization including applied power for polymerization, pressure, plasma exposure time and flow rates were studied. The effects of experimental variables such as the operating potential of the working electrode, mediator concentration and pH of the measured solution were investigated for the optimum analytical performance by using an amperometric method, and the plasma polymerized polyethylene diamine film was examined by Fourier transform infrared spectroscopy. The biosensor provided a linear response to hydrogen peroxide over a concentration range of 5×10^-7—1.1×10^-3 mol/L and a detection limit of 0.3 μmol/L. The recovery studies for H₂O₂ in the real samples gave satisfactory results.

Identification of Selective Regions in Overlapping Hyphenated Chromatographic Data Using Three-dimensional Latent Projective Graph(3D-LPG) and Chemometric Technique

QI Yun-Peng, WU Yu-Tian, CHAI Yi-Feng, LI Tong-Hua, FAN Guo-Rong, LU Feng

2004, 25(10):  1825-1829. 

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Selective regions of the overlapping hyphenated chromatographic data are crucial for the resolution via chemometric methods. The latent projective graph(LPG) is the common technique for identifying the selective regions, in which the selective regions are revealed by the appearance of sequences of consecutive points mapping as segments of straight lines. However, according to our results, the straight lines in the LPG of the system comprising some closely eluting components with fairly similar spectra may not always necessarily correspond to the real selective regions. In this work, three-dimensional LPG(3D-LPG) was developed, and a new chemometric technique T-plot was proposed to identify the linear segments of 3D-LPG corresponding to the selective regions. The performance and efficiency of the proposed methods were illustrated on both the simulated and experimental data, and the results show that the 3D-LPG can provide much more information and deeper insights into the structure of the data, outperforming the present 2D version in revealing the selective regions when the spectra of some coeluting components are quite similar. Moreover, T-plot is proved to be effective in identifying the linear segments in 3D-LPG.

Non-covalent Interaction Between Oligodeoxynucleotide and Alkaloid Compounds via Negative Ion Electrospray Mass Spectrometry(Ⅰ)

SONG Feng-Rui, LIU Ning, YAN Cun-Yu, LIU Zhi-Qiang, LIU Shu-Ying

2004, 25(10):  1830-1832. 

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Oligodeoxynucleotide from SARS virus was selected and synthesized. Its complexes with alkaloid compounds were investigated by electrospray mass spectrometry. We found that three alkaloid compounds could interact with the DNA target molecule in five alkaloids analyzed. With increasing molar ratio of the three alkaloid compounds, the complexes between alkaloids and DNA with different stoichiometric ratios were found in their MS spectra. The order of the alkalinity of their gas phase corresponds to that of liquid phase, that is: Palmatine>Jatrorrhizine>Berberin. The relative abundance of these complexes in mass spectra can assess the relative affinities of above three alkaloid compounds with the DNA target molecule. In this paper, the binding sites between jatrorrhizine and DNA was deduced from the interaction experiments of jatrorrhizine with three nucleosides.

Voltammetric Determination of L-Cysteine at Cyclodextrin-incorporated Carbon Nanotubes Modified Electrode

XIAO Su-Fang, WANG Zong-Hua, LUO Guo-An, WANG Yi-Ming

2004, 25(10):  1833-1835. 

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A novel modified electrode was constructed by casting α-cyclodextrin-incorporated carbon nanotubes on graphite surface to form a functionalized interfacial layer. The modified electrode exhibits an excellent electrocatalytic activity for the oxidation of L-cysteine. The currents(measured by different pulse voltammetric techniques) increase linearly with the increase of the concentration of L-cysteine in the range from 1×10^-6 to₂×10^-3 mol/L. The detection limit is 2×10^-7 mol/L. The modified electrode has the best properties of the two components of the system, such as the electrocatalytic properties of carbon nanotubes and the molecular recognition and accumulation abilities of α-cyclodextrin. The result demonstrates that it has a good stability and reproducibility and is available in the detection of L-cysteine in urine.

Synthesis and Extracting Abilities of Calix[4]resorcinarene-based Schiff Base Derivatives

GE Yun, YAN Chao-Guo

2004, 25(10):  1836-1839. 

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Two noval calix[4]resorcinarene-based Schiff bases, 4a and 4b, which contain eight or twelve long salicylideneimine chains were easily synthesized by treating the corresponding calix[4]resorcinarenes bearing amine chains with different lengths, 3a and 3b, and salicylaldehyde in alcohol. These two amides, 3a and 3b, were obtained in a high yield by treating activated ethoxycarbonylmethoxy substituted derivatives 2a and 2b with excess 1,6-hexanediamine. All the organic compounds were characterized by IR and ¹H NMR spectroscopy. It was found that the functional salicylideneimine arms appended to the peripheries of calix[4]resorcinarenes can fine-adjust the size and shape of the cavity upon complexation with metal ions, which significantly enhances the cation extractability.

Synthesis of Novel 2-Oxo-1,2,4-[triazolo][3,2-d] [1,5]benzoxazepine Derivatives

LI Zheng, WANG Quan-Rui, TAO Feng-Gang

2004, 25(10):  1840-1844. 

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Many [1,2,4]triazolobenzoheteroazepine derivatives show interesting biological activities. In this paper, the geminal arylazo isocyanato compounds 3 were prepared from chroman-4-ones in three steps, i.e. condensation with arylhydrazine, cycloaddition of the resulting hydrazone with HNCO, and oxidative ring cleavage by KMnO₄. Compounds 3 were allowed to react with HBF₄, producing the respective 3-spiro substituted 1-aryl-4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 4. The concurrent rearrangement of compound 4 with insertion of the nitrogen atom into the carbon skeleton provided, after the basic work-up, 2-oxo-[1,2,4]triazolo[3,2-d][1,5]benzoxazepines 5a—5h. An unambigous structutal proof was obtained from the X-ray diffraction analysis for compound 5h.

Stroma-free Hemoglobin Cross-linked with O-Raffinose and Glutaraldehyde

WANG Yan-Feng, PAN Ji-Lun, YU Yao-Ting

2004, 25(10):  1845-1848. 

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Red cell substitutes are group of oxygen carriers designed to temporarily replace transfused blood. In this paper, a kind of red cell substitutes based on polymerized hemoglobin were prepared and in vitro characteristics were studied. Firstly, Stroma-free hemoglobin(SFHb) was purified from outdated human blood. SFHb was intramolecularly crosslinked with O-Raffinose, prepared from the ring opening oxidation of raffinose. The intramolecular crosslinking between amino groups within 2,3-DPG binding pocket contributes to high P₅₀. Then O-Raffinose-Hb was intermolecularly crosslinked with glutaraldehyde under the optimized crosslinking condition. The process of crosslinking was monitored by SDS-PAGE and Sepharose gel chromatography. The percentage of the component of polyhemoglobin with a molecular weight range of 130 000—600 000 was 76.9%.

Isolation and Identification of Cyclopeptides from the Roots of Schnabelia tetradonta

DOU Hui, LIAO Xun, CHEN Chang-Xiang, PENG Shu-Lin, ZHOU Yan, DING Li-Sheng

2004, 25(10):  1849-1852. 

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Four cyclopeptides were isolated from the roots of Schnabelia tetradonta, a Chinese endemic herb, through repeated column chromatography on normal and reversed phase silica gel. On the basis of spectroscopic and chemical evidence, the structures of two new cyclopeptides were elucidated as cyclo(N-Pro¹-Pro²-Phe¹-Phe²-Leu¹-Ser-Thr-Leu²-CO)(1, schnabepeptide C) and cyclo(N-Pro¹-Pro²-His-Gly-Val-Asn-Ile-Trp-CO)(2, schnabepeptide D), and other two cyclopeptides were schnabepeptide B(3) and schnabepeptide(4), respectively.

Synthesis of a CCK-8 Tetrapeptide Fragment by Enzyme-catalyzed Method

XIANG Guang-Ya, LÜ Zi-Min, HEINER Eckstein

2004, 25(10):  1853-1856. 

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Cholecystokinin(CCK) is a polypeptide hormones with gastrointestinal, biliar and brain activities. Many methods were reported on the synthesis of the C-terminal octapeptide. Enzymatic techeiques possess numerous advantages over chemical techniques for the formation of the peptide bond. Here we reported an enzyme-catalyzed method to synthesize a cholecystokinin tetrapeptide(Phac-Met-Gly-Trp-Met-OEt) fragment. It was synthesized by coupling Phac-Met-OEt with Gly-OMe·HCl, Trp-OMe and Met-OEt successively, these three steps were catalyzed by α-chymotrpsin, papain and α-chymotrpsin respectively. The influence factors on the reaction including the choice of enzymes, solvents, acyl donor and buffer contents were also studied. All the reaction intermediates and products were confirmed to have the correct molecular mass by the results of FAB-MS.

Total Chemical Synthesis of Three Novel Actinomycin D Analogs Used as Antitumor Drugs

ZHANG Bang-Zhi, WANG Ze-Zhou, WANG Xiao-Li, LI Xin-Lei, NI Jing-Man, WANG Rui

2004, 25(10):  1857-1859. 

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Actinomycin D(AMD) is well known for its specific inhibition of DNA transcription, and has been used clinically as an antitumor drug for the treatment of some highly malignant tumors. Based on the former research, two [D-Phe²]₂AMD analogs with L-MeVal(the fifth amino acid residue in the cyclic depsipeptide of AMD) substituted by D-MeVal and D-MePhe were designed to reduce the toxicity and increase the antitumor activity. Another analog in which the D-Val residue replaced with D-MeVal was designed to eliminate or to weaken the hydrogen bonds of D-Val residues between α and β rings. All three novel compounds were prepared from C terminal to N terminal in solution phase to form linear pentapeptides, and cyclized by BOP-Cl/Et³N in DCM. Condensation of pentapeptide lactone with BMNBCA, followed by catalytic reduction, controlling oxidation by K₃Fe(CN)₆ and purification afforded the analogs as red solid. The spectrum data of all three analogs including HR-MS, ¹H NMR and [α] D were given.

Highly Effective Reduction of 2″,3″-Dibromocephalomannine Under Ultrasound Irradiation

JIN Xiao-Ying, LI Ming, CHEN Jian-Min, CHEN Jia-Kuan, DU Ying-Xiang

2004, 25(10):  1860-1862. 

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Dibromocephalomannine(DIBROCs)is the intermediate product in the purification of taxol. In this paper, we successfully realized the efficient conversion of DIBROCs to cephalomannine under ultrasound irradiation for the first time. Ultrasound irradiation, a favorable acceleration of reaction rates, could solve the problems of incomplete conversion of DIBROCs to cephalomannine and the by-products due to long reaction time under the traditional stirring condition. The results showed that under ultrasound irradiation zinc powder was more effective than other metal powder and the proper reaction temperature was 20 ℃. Under this condition the conversion was more than 98% in 40 min.

Reaction of Hydroxy-substituted Polycyclic Aromatic Hydrocarbons with Nitric Oxide

LEI Lian-Di, ZHANG Hong-Rui, YANG De-Suo, WU Long-Min

2004, 25(10):  1863-1865. 

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The reaction of a series of hydroxy-substituted polycyclic aromatic hydrocarbons(PAHs)with nitric oxide containing trace O₂ was carried out in CH₂Cl₂ at room temperature. The products identified by IR, NMR and HRMS indicate that the mono nitration at para- or ortho-position with respect to hydroxy group on the benzene ring occurred regioselectively. The reactions are assumed to be initiated by single electron transfer and the reaction intermediates may be resonance stabilized phenoxy-like radicals.

Influence of Reaction Time, Temperature and Solvent on the Self-assembly into Oligo-peptides for Valine

LI Hong, ZHAO Wen-Jie, CAO Shu-Xia, LU Kui, ZHAO Yu-Fen,

2004, 25(10):  1866-1868. 

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Owing to having very strong bioactivity, oligo-peptides can be used as the medication or the pre-medication and become the studying focus now. Existing methods for synthesizing oligo-peptides included liquid phase peptide synthesis, solid phase peptide synthesis and enzymatic peptide synthesis. In this paper, a new method for synthesizing oligo-peptides by phosphorus oxychloride activation was reported. With the assistance of phosphorus oxychloride, the phosphorylation of L-valine could take place and then was assembled into oligo-peptides, which were analyzed by electrospray ionization mass spectrometry(ESI-MS). On quenching with methanol, the reaction mixtures, which were produced under different reaction conditions, yielded the corresponding peptide methyl esters. Moreover, we found that, as the reaction conditions such as reaction time, solvent and temperature were changed, the length of peptides changed. And the length of peptides could be controlled by changing the reaction conditions.

Release Properties of Glyphosate from a Supramolecular Glyphosate Intercalated MgAl-LDH

ZHANG Xian, ZHANG Hui, WEI Min, Evans D. G., DUAN Xue

2004, 25(10):  1869-1874. 

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Glyphosate intercalated magnesium aluminum layered double hydroxides (MgAl-LDH-gly), a novel controlled-releasing herbicide formulation, was synthesized by using a new method involving separate nucleation and aging steps developed in our lab, and characterized by XRD and IR spectroscopy. First of all, the release property of MgAl-LDH-gly was studied in pure H₂O and Na₂CO₃ solution, respectively. Furthermore, its release behavior was studied in phosphate buffer solutions with different pH values and in mixed inorganic anions solution in order to investigate the influence of environmental factors. The results indicate that the release of MgAl-LDH-gly is actually an anions exchange process, and the primitive release process accords with the first-order kinetics equation. It is shown that MgAl-LDH-gly can be used more effectively in weak alkali or neutral environment than in weak acid environment. The quantity of released gly is decided by the whole concentration of inorganic anions in solution in our experimental range.

Effect of ZnFe₂O₄ Dopant on Structural Phase Transformation and Photocatalytic Activity of TiO₂ Nanopowders

YUAN Zhi-Hao, SUN Yong-Chang, WANG Yu-Hong, BIE Li-Jian, DUAN Yue-Qin, ZHANG Li-De

2004, 25(10):  1875-1878. 

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ZnFe₂O₄ and TiO₂ nanopowders were prepared by coprecipitation and sol-gel methods, respectively. Influence of ZnFe₂O₄ dopant on the anatase-to-rutile phase transformation of TiO₂ was investigated, and the photocatalytic activity of ZnFe₂O₄ doped TiO₂ nanopowders was evaluated by phenol degradation under sunlight irradiation. It was found that the phase transformation could be strongly promoted by doping ZnFe₂O₄ component in TiO₂ nanopowders, and an increase in the activity by a factor of 2₃ relative to pure TiO₂ nanomaterials was obtained under the optimum conditions.

Preparation of Multi-walled Carbon Nanotubes by CVD over Transition Metal Catalyst Supported on Nanocrystallite CaCO₃

LUO Zhi-Qiang, ZHANG Xiao-Bin, CHENG Ji-Peng, LI Yu, LIU Fu, TAO Xin-Yong, YIN Wan-Zhong, HAN Yue-Xin

2004, 25(10):  1879-1884. 

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Multi-walled carbon nanotubes(MWNTs) were synthesized by chemical vapor deposition(CVD) over transition metal catalyst supported on nanocrystalline CaCO₃. The compositions and the preparation conditions of the catalysts were studied and the nanotubes synthesized were characterized by field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), high transmission electron microscopy(HREM), XRD and Raman spectroscopy. The results show that the high specific surface area of nanocrystallite CaCO₃ has the advantage to load metal nanoparticles with a high density. The prepared Fe-Co bimetallic catalyst was the best catalyst for CNTs synthesis. An ideal condition for CNTs′ forming is 700 ℃ for 60～90 min with proper decomposition speed of nanocrystallite CaCO₃ at early stages of CNTs synthesis, and the yield of CNTs with the outer diameter of 15～25 nm is 11 g MWNTs/g catalyst. The purity can reach 97% by sonication in 30% nitric acid based on thermal gravimetric analysis results. The structures of the carbon nanotubes were not damaged proved by Raman spectroscopy.

UV Photodissociation Dynamics of n-Alkyl Bromide

ZHU Rong-Shu, TANG Bi-Feng, JI Lei, TANG Ying, ZHANG Song, WANG Yan-Mei, ZHANG Bing

2004, 25(10):  1885-1888. 

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With the deep development of environmental investigation, some alkyl bromides of higher homolog(e.g., C₂H₅Br, n-C₃H₇Br, n-C₄H₉Br) in the lower stratosphere have attracted a little attention in recent years. But the photodissociation dynamics of them have not been studied. In this work, we reported the photodissociation dynamics of n-alkyl bromides R_Br(R=n-alkyl radical)(C₂H₅Br, n-C₃H₇Br, n-C₄H₉Br) at 234 and_267nm using resonace-enhanced multiphoton ionization (REMPI) with time-flight mass spectrometry(TOF-MS) and the goal was to study the dependencies of the relative quantum yields of φ(Br^*) and φ(Br) on photon energy and the molecular complexity. The measured values of the φ(Br^*) were found to be φ(Br^*)_234nm=0.286 and φ(Br^*)_267nm=0.338 for C₂H₅Br, φ(Br^*)_234nm=0.356 and φ(Br^*)_267nm=0.294 for n-C₃H₇Br, φ(Br^*)_234nm=0.428 and φ(Br^*)_267nm=0.341 for n-C₄H₉Br.The results of φ(Br^*) clearly showed an increasing tendency with the increase of molecular complexity at 234 nm(C₂H₅Br<n-C₃H₇Br<n-C₄H₉Br), while the φ(Br^*) at 267 nm showed a relatively little change. Simultaneously, the φ(Br^*) was found to be strongly dependent on the excitation energy except for C₂H₅Br and showed an increasing tendency with the increase of photon energy[φ(Br^*)_267nm< φ(Br^*)_234nm]. This increasing tendency of φ(Br^*) with the increase of excitation energy was in good agreement with the results observed in photodissociation of n-alkyl iodides.

Kinetics Study of Iron Release of Human Serum Ferritin with MALDI-TOF Mass Spectrometry and Electronic Spectrum Technology

YAN Li, HUANG He-Qing, JIN Hong-Wei, CHEN Ping, YANG Tian-Ci, WANG Qun-Li

2004, 25(10):  1889-1892. 

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MALDI-TOF mass spectrometry was used to understand the compound of proteins in human serum and electronic spectrum was used to study the kinetics of iron release of the human serum ferritin. The result shows that if Na₂S₂O₄ was taken as the reducer, it is impossible to examine the iron release in serum with normal spectrum. When Vc was used as the reducer, the kinetic reaction of the iron release from serum ferritin was the first-order. It might be due to the abundance and influence of other proteins in human serum in the course of iron release, and that could fit the need of iron in the body.

Laser Flash Photolysis of CS₂-HNO₂ Aqueous Solution Complex System

Fang Hao-Jie, OU-YANG Bin, ZHU Cheng-Zhu, DONG Wen-Bo, ZHANG Ren-Xi, PAN Xun-Xi, HOU Hui-Qi

2004, 25(10):  1893-1896. 

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The photolysis mechanism of N 2-saturated CS₂-HNO₂ aqueous solution was studied by means of the laser-photolysis/transient absorption technique at 355 nm. Spectra analysis shows that the oxidation of CS₂ in HNO₂ aqueous solution occurs via a complex reaction mechanism.One route is the rapid addiction of ·OH to CS₂ to form CS₂OH adduct, which successively reacts with HONO to form CS₂OH-HONO adduct.Five transient absorption peaks(285, 305, 475, 490 and 980 nm) are attributed to CS₂OH-HONO and the rate coefficient for CS₂OH+HONO reaction is (2.79±0.05)×10⁸ L/(mol·s). The other reaction route is addiction of NO⁺ to CS₂ to form CS₂NO⁺ adduct which has an absorption peak of 230 nm. The first order decay rate coefficient for CS₂NO⁺ is 1.28×10⁵ s^-1.

Density-functional Study of the Adsorption of ZnO on α-Al₂O₃(0001) Surface

YANG Chun, LI Jin-Shan, LI Yan-Rong

2004, 25(10):  1897-1900. 

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ZnO adsorption on the α-Al₂O₃(0001)2×1 surface was studied by using dynamics calculations based on density-functional theory and pseudopotential method. The process of the ZnO adsorption, the bonding orientation and bonding characteristics were studied in details. The bond length(0.185±0.01) nm of Zn_O at the stable adsorbed sites has just 30° rotation away from the O hexagonal symmetry of the α-Al₂O₃(0001) surface, which are in agreement with recent experimental results. The atomic population and PDOS reveal that the bonding between the O^2- of ZnO and the Al³⁺ of the α-Al₂O₃(0001) surface shows a strong ionic characteristic, and the Zn²⁺ chemisorbed with the surface O shows covalent bonding properties.

NMR Self-diffusion Studies on the Interaction Between α-Cyclodextrin and Fatty Acids

XU Min, ZHANG Hui-Ping, CHEN Qun

2004, 25(10):  1901-1904. 

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The association between α-cyclodextrin and three kinds of short chain fatty acids was studied by NMR self-diffusion measurements. Dilute solution condition was adopted to avoid precipitating of the solutes. The diffusion coefficient of fatty acid in the solution, which reflects the strength of association between α-cyclodextrin and fatty acids, was found to decrease with increasing alkyl chain length of fatty acid. Together with 2D-ROESY experiment, therefore, it was demonstrated that in forming inclusion complex, the hydrophobic interaction is predominant among various possible interactions between α-cyclodextrin and fatty acids.

Time-resolved Fluorescence Spectroscopic Studies on the Binding of L-[4-(1-Pyrene)butyroyl]-phenylalanine with Proteins

CHEN Kai, ZHAI Chun-Xi, LI Wen, WU Li-Xin, WU Yu-Qing, ZHANG Jian-Ping, AI Xi-Cheng

2004, 25(10):  1905-1908. 

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Time-resolved fluorescence spectra was applied to studying the binding of L-[4-(1-pyrene)butyroyl]-phenylalanine(PLP) with lysozyme(lys), bovine serum albumin(BSA) and human serum albumin(HSA). The fluorescence lifetimes of pyrenyl group quenched by using cobalt(Ⅲ) hexaamine(CoHA) in free state and in different complexes protein systems were also investigated. These results suggest that PLP binds with SAs via its pyrenyl group insertion in the hydrophobic cavity of protein, whereas it binds with Lys in the hydrophobic area on the surface.

Promotion Effect of Heteropoly Acids Modified Electrode to Methanol Electrochemical Oxidation

LÜ Yan-Zhuo, HAN Fei, LIU Chang-Peng, LI Chang-Zhi, XING Wei, LU Tian-Hong, SANG Ge

2004, 25(10):  1909-1911. 

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Improving the rate of anode reaction in direct methanol fuel cell(DMFC) is the key to increasing the output power of DMFC. In this article, two kinds of heteropolyacids were applied to modify the platinum electrode and their effect on the methanol electrochemical oxidation was studied. The results show that the PWA and SiWA modified platinum electrodes have a promoting effect to the methanol electrochemical oxidation compared with the non-modified platinum electrode.

Effects on the Conformations and Host-guest Interaction of Calix[4]pyrroles Substituted by Halide on β Positions(Ⅰ)——Molecular Mechanics/Molecular Dynamics Study

CHEN Pei-Quan, SUN Hong-Wei, CHEN Lan, SHEN Rong-Xin, YUAN Man-Xue, LAI Cheng-Ming,

2004, 25(10):  1912-1915. 

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The calix[4]pyrroles are new heterocalixarene analogues that show interesting anion and neutral substrate binding properties. In this paper, a series of molecular mechanics and molecular dynamics simulations were performed to obtain stable conformations of four free calix[4]pyrroles and their corresponding host-guest complexes with halide anions; A dipole model was provided to explain how the substitutions by halide on β positions affected the conformations and host-guest interaction of calix[4]pyrroles. These effects was due to the difference of dipole moments in pyrroles rings. Binding energies of the calix[4]pyrrole-halide anion complexes were calculated. Replacing the β-pyrrolic hydrogens by halide atoms served, respectively, to greatly increase the anion binding affinities.

Preparation of Filler-type Solid Acid for Catalytic Distillation and Its Catalytic Activity

DU Chang-Hai, WANG Shu-Jiang, YANG Ji, QIN Yong-Ning, HE Yan-Feng, MA Zhi

2004, 25(10):  1916-1919. 

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A novel solid acid SO₄^2-/Al₂O₃-Al catalyst for catalytic distillation was prepared by impregnation of anodized aluminium plates formed by anodic oxidation of high-purity aluminium foils with aqueous H₂SO₄, and characterized by SEM, BET, XRD and NH 3-TPD. XRD patterns of the samples show that the support anodized Al₂O₃ layer is amorphous oxide supporting. NH 3-TPD results show that the catalyst has intermediate acid sites. The catalyst was active for the esterification of acetic acid with ethanol, and can be reused directly for 5 times, which means the catalyst has a good stability.

Surface-enhanced Raman Spectra of C₇₀ Molecules Adsorbed on the Surface of Copper

GAO Ying, ZHANG Zhen-Long, BAI Ying, MO Yu-Jun

2004, 25(10):  1920-1923. 

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The SERS effect of C₇₀ molecules adsorbed on the surface of copper was reported for the first time. By comparing with the normal Raman and the SERS on the surface of silver, it sounds reasonable that the adsorption between the copper and C₇₀ is a physical adsorption, and electromagnetic enhance mechanism dominates over the surface enhanced effect. The difference of relative intensities between the SERS spectra of C₇₀ adsorbed on the silver surface and copper surface originates from different adsorption states of C₇₀ molecules on them. Judged by the vibration mode of C₇₀, the adsorption states on the two different metal surfaces could be described as near “horizontal” and near “upending” directions, respectively. This investigation is valuable for the research of interaction between C₇₀ molecules and different metal surfaces.

Effect of Purification of Carbon Nanotubes on Catalytic Activity of Pt/CNTs in Electrochemical Oxidation of Methanol

DU Bing-Chen, LIU Chang-Peng, HAN Fei, XING Wei, LU Tian-Hong, SANG Ge

2004, 25(10):  1924-1927. 

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Carbon nonotubes(CNTs) were considered as the potential supports for heterogeneous catalysts, especially for liquid-phase reaction. A novel method for CNTs purification was proposed and a catalyst Pt/CNTs were obtained by using the method. The catalyst was characterized by TEM, XRD, BET and cyclic voltammogram curves and applied to the electrochemical oxidation of methanol. It is found that the purification methods have an obvious influence on the catalytical activities of Pt/CNTs towards the electrochemical oxidation of methanol, and the catalytic performance of the cathodic catalyst Pt/CNTs with CNTs as the support which was obtained by multi-step purification method is much better than that of the catalyst Pt/CNTs obtained by mixed acid oxidation purification

Miniatured H₂/Air Self-breathing Proton Exchange Membrane Fuel Cell Fabricated by MEMS Technology

WANG Tao, CHEN Cong, LI Ju-Feng, ZHANG Xi-Gui, XIA Bao-Jia, LI Xin-Xin

2004, 25(10):  1928-1930. 

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A miniaturized H₂/air self-breathing proton exchange membrane fuel cell(μPEMFC) was designed and fabricated with 1 cm² active area. All the basic parts of a conventional H₂/air PEMFC were incorporated in a smaller and simpler package. The electrodes of the μPEMFC were constructed on silicon wafer substrates by means of standard micro electromechanical systems (MEMS) techniques. The obtained results show that the peak power density of a single cell has exceeded 110 mW/cm² when it was operated in ambient atmosphere at 20 ℃. Furthermore, the cells can yield over 400 W/L specific power density.

Fabrication of Grating Waveguide and Coupling Grating Using Two-photon Initiated Photopolymerization

YU Xiao-Qiang, ZHANG Xian, XU Gui-Bao, ZHAO Hua-Ping, HE Wei, SHAO Zong-Shu, JIANG Min-Hua, SUN Yu-Ming, LIU En-Quang

2004, 25(10):  1931-1933. 

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Two ternary materials systems, which comprise two-photon initiators, oligomer and poly(methyl methacrylate), were prepared. A polymeric waveguide film was manufactured by spinning the materials on ITO, and the two-photon initiated photopolymerization(TPIP) was carried out successfully in the waveguide film. Consequently, an approach using TPIP is demonstrated for fabrication of grating in a thin polymeric film possessing waveguide properties. The results show that the resulted grating can manipulate and couple light.

Isopiestic Determination of Vapor Pressures and Osmotic Coefficients and the Ion-interaction Model for Li₂B₄O₇-H₂O System at 298.15 K

ZHANG Ai-Yun, YAO Yan, SONG Peng-Sheng

2004, 25(10):  1934-1936. 

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Isopiestic molalities, vapor pressures and osmotic coefficients of aqueous Li₂B₄O₇ solutions from 0.027 5 to 2.939 7 mol/kg were determined at 298.15 K by using an improved apparatus. The rule of the changes in vapor pressure over aqueous Li₂B₄O₇ solutions was revealed, which indicated that the bond of borate anions with water are better than that of NaCl. The different formation reaction equilibria for the species containing boron of boric acid and borate anions B(OH)₄^-, B₃O₃(OH)₄^- and B₄O₅(OH)₄^2- in Li₂B₄O₇(aq) solutions were taken into account. The stoichiometric equilibrium constants for the formation reactions of the boron species and the ion-interaction parameters were estimated simultaneously by using Pitzer equations of osmotic coefficient with minor modifications. Sixteen parameters were obtained with a standard deviation 0.005 5 for the ion-interaction model.

Curing Reaction Kinetics of Epoxy Resin Containing Biphenyl Structure Using DDS as Curing Agent

ZHANG Chun-Ling, MU Jian-Xin, YU Wen-Zhi, MI Xin-Yan, FU Tie-Zhu, PANG Jian-Xun, NA Hui, WU Zhong-Wen

2004, 25(10):  1937-1940. 

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The reaction process of the curing system(TMBP/DDS) was studied by DSC and carefully analyzed. Based on the Kissinger method and Ozawa method, the apparent activation energy(ΔE) was got 69.7 and 74.2 kJ/mol respectively. The reaction order(n=0.89) and frequency factor A in various temperature were calculated according to Crane theory. The curing reaction condition was made by using DDS as the curing regent.

Reactive Blend Systems of PA6/HIPS/PP-g-(GMA-co-St)

LI Zhi-Jun, XIE Xu-Ming, GUO Bao-Hua

2004, 25(10):  1941-1944. 

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The glycidyl methacrylate(GMA) and styrene(St) multi-monomers melt grafted PP[PP-g-(GMA-co-St)], was used as a reactive compatibilizer of PA6/HIPS blends. The reactive blend system of PA6/HIPS/PP-g-(GMA-co-St) was studied by DSC, SEM and determinations of MFR, torque values and mechanical properties. The results showed that the crystallinity and melting temperature of PA6 were reduced and the interfacial tension and adhesion of the PA6/HIPS were improved in the presence of the PP-g-(GMA-co-St). The micrographs showed the better effect of compatibilization of the PP-g-(GMA-co-St) on the PA6/HIPS blends. When the content of the PP-g-(GMA-co-St) was 10%, the mechanical properties of the PA6/HIPS/PP-g-(GMA-co-St) were much improved; the impact strength of the blend surpassed the pure PA6 and reached the level of the pure HIPS. PA6/HIPS/ PP-g-(GMA-co-St) plastics alloy with the proportionate and good mechanical properties has been obtained by the reactive blend.

Rapid Living Free-Radical Polymerization of Methyl Acrylate Under ⁶⁰Co γ-ray Irradiation in the Presence of Benzyl ¹H-Imidazole-1-Carbodithioate

HUA Dao-Ben, BAI Ru-Ke, LU Wei-Qi, PAN Cai-Yuan

2004, 25(10):  1945-1948. 

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The free radical polymerization of vinyl monomers under ⁶⁰Coγ-ray irradiation(52.5 Gy/min) in the presence of benzyl ¹H-imidazole-1-carbodithioate(BICDT) was studied. The polymers were characterized by GPC and ¹H NMR. The results show that the molecular weight increases linearly with the increase of the monomer conversion, the molecular weight distribution(MWD) is narrow and a linear relationship between ln([M]₀/[M]) and polymerization time exists. All of these evidences indicate that the polymerization of MA is a living free radical polymerization. It is worthy to be noticed that the polymerization of methyl acrylate(MA) is quite fast, molecular weight(M w) is as large as 39 600 g/mol at 68% conversion with M_w/ M_n=1.08 within 68 min.

Preparation of Chitosan/Hydroxyapatite Nanocomposite with Layered Structure via in-situ Compositing

LI Bao-Qiang, Hu Qiao-Ling, WANG Mang, SHEN Jia-Cong

2004, 25(10):  1949-1952. 

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Incorporation of hydroxyapatite(HA) with chitosan(CS) could improve the bioactivity and the bone-bonding ability of CS/HA composite, which maybe sacrifice its mechanical properties. The CS/HA nanocomposite with a high performance was prepared via in-situ compositing route. The key of in-situ compositing is that a pre-precipitated CS membrane was used to obstruct the CS/HA precursor from NaOH aqueous solution. The CS membrane controlled the process of CS precipitation and transformation of HA from the precursor due to changing of pH simultaneously and tardily. XRD were carried out to determine the component of CS/HA composite. TEM and SEM were performed to investigate the morphology of HA granules and CS/HA composite. The results showed that the in-situ formed calcium phosphate in CS was exactly HA, and that nano-size HA granules(30—50 nm width, 100 nm length) were dispersed in CS matrix uniformly. The result of SEM shows that the structure of CS/HA composite prepared by in-situ compositing is layered-by-layered, which can further prove the mechanism of in-situ compositing. The mechanical properties of CS/HA were evaluated by the three point bending test. The bending strength and modulus of CS/HA(mass ratio 100/5) are 86 MPa and 3.4 GPa, which is much higher than that of cancellous bone, 22 MPa. This material is of potential application as bone substituent in hard tissue reparation.

Water-vapor Permeability of Hydrophilic Polyurethanes Studied by Positron Annihilation

WANG Zhi-Fen, QI Ning, WANG Bo, DING Xue-Mei, HU Jin-Lian

2004, 25(10):  1953-1957. 

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Positron annihilation lifetime spectroscopy was used to study the effect of temperature and content of PEG on the free volume size, distribution and water-vapor permeability(WVP) for a series of polyester-based polyurethane films based on poly(butylene adipate)(PBA) as soft segments. The PALS results indicated that the mean volume of free-volume increased and the distribution of free-volume broadened with the temperature increased. The variation rate of free-volume hole size as a function of temperature has an abrupt increase, which is attributed to the crystalline region melting. In all membranes, water-vapor permeability coefficient increased with the increase of temperature. PBA-20 has almost the same values of WVP as PBA-10 and PBA-15. More PEG groups added exert no significant effects on the water-vapor permeability, because there are two opposite effects of PEG groups on WVP. The experimental results indicated that WVP could be controlled by not only free volume, but also hydrophilicity of polymer.

Crystallization Behavior of the Copoly(vinylidene fluoride-chlorotrifluoroethylene)

FU Hai-Tao, CHEN Wei, YU Ying, FAN Zhong-Yong, NIE Fu-De, WANG Jian-Hua

2004, 25(10):  1958-1961. 

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The crystallization behavior and crystals structures of copoly(vinylidene fluoride-chlorotrifluoroethylene), which was synthesized with n(NDE):n(CTFE)=1:4, were investigated by DSC, WAXD and FTIR, respectively. The experimental data show that the copolymer is one of the semicrystalline polymers. By means of DSC, the thermal analysis of the samples annealed at 313—353 K indicated that their melting temperature and crystallinity increased as the annealing time increased. During the annealing process, the crystals become perfect through segment reorganization. As a result, average lamellar thickness of copolymer annealed at 353 K was estimated about 4.68 nm according to the melting point of the sample. Average crystal dimension normal to(101) was calculated to be 5.86 nm and the interplanar crystal spacing along to(101) was measured to be 0.55 nm by using WAXD. Annealed at 333 K for 720 h, it was revealed that the maximum crystallinity of copolymer was about 14%.

Reactivity Ratios and Copolymer Composition of Vinyl Chloride and N-Substituted Maleimide Copolymerization

DU Miao, WENG Zhi-Xue, SHAN Guo-Rong, HUANG Zhi-Ming, PAN Zu-Ren

2004, 25(10):  1962-1965. 

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Radical copolymerization of vinyl chloride(VC) with N-substituted maleimide were conducted in tetrahydrofuran at 60℃ with AIBN as initiator. Based on the copolymer composition and monomer composition, the copolymerization parameters(r₁, r₂, Q and e) of each monomer pair were determined. The reactivity ratios of N-substituted maleimide monomers were all larger than that of VC, indicating that these monomers were more active. The effects of substituted groups on reactivity ratios were also discussed, and N-substituted maleimide monomer had a larger Q value than that of VC, especially for phenyl substituted maleimide monomer. It was believed that this phenomenon was related to the conjugated effect of phenyl group in N-substituted maleimide. The location of substituent on phenyl would influence Q value of N-substituted phenyl maleimide monomer. para-Substituent(i.e. p-ClPMI and p-MPMI) phenyl maleimide has a large Q value than that of ortho- and meta-substituted phenyl maleimides. In addition, there is a larger difference between e₁ and e₂, which means the large alternating tendency of the copolymerization of N-substituted maleimide with VC. The copolymer compositions for VC/N-substituted maleimide solution copolymerization varied greatly with conversion, especially for small N-substituted maleimide feed ratios. Subsequently, recurrence method deduced from Mayo-Lewis was used for predicting the change of copolymer composition with conversion. In addition, this method is also used to calculate the critical weight [(x_w)_c] conversion for VC/N-substituted maleimide copolymerization systems at different VC monomer feed fractions.

Synthesis and Properties of Poly(vinyl alcohol)-g-poly (ethylene glycol)Monomethyl Ether Polymeric Solid-solid Phase Change Material

ZHANG Mei, MA Rong-Tang, JIANG Zhen-Hua

2004, 25(10):  1966-1968. 

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The soluble poly(vinyl alcohol)-g-poly(ethylene glycol) monomethyl ether(PVA-g-MPEG) graft copolymer was prepared by two-step synthesis. The structure of the PVA-g-MPEG was characterized by ¹H NMR. The phase change and crystallization behavior were analyzed by DSC and POM. The phase change behavior presented solid-to-solid state; the phase transition process was reversible. Compared with pure MPEG, the phase change temperature and enthalpy of graft copolymer declined because of the addition of PVA. Due to the intermolecular interaction and chemical bond, the crystalline shape of the graft copolymer was changed.

Effect of Filler Surface-Treatment on Dynamic Viscoelastic Properties for PMVS/SiO₂ Composites

CHEN Chun-Rong, ZHENG Qiang, HU Hong-Guo

2004, 25(10):  1969-1971. 

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The dynamic viscoelastic behavior of polysiloxanes filled with ultrafine SiO₂ has become ever-lasting important due to its unique properties. In present article, the influence of SiO₂ treated with silane coupling agent bis(3-triethoxysilyl)tetrasulfane(TESPT) on dynamic viscoelastic properties of uncured polymethylvinylsiloxane(PMVS)/ultra fine-silica(SiO₂) composites was investigated by using an advanced rheometric expansion system(ARES) under the conditions of temperature²5 ℃, strain(γ) from 0.01% to 100% and frequency(ω) from 0.01 to 100 rad/s. The results reveal that the treated SiO₂ particles leads to the frequency-dependent storage modulus(G′) which approaches linear viscoelastic behavior in the lower frequency region. Based on an examination of the dynamic viscoelastic behavior and TEM observation, we owe these characteristics to improved dispersion of SiO₂ particles in the polymer matrix due to their surface-treatment as compared with the untreated case. On the other hand, dynamic viscoelastic behavior sensitively reflects the dispersion of SiO₂ particles with diameters from 100 to 500 nm, which further evidence the promotion of filler dispersion induced by the incorporation of TESPT.

Synthesis and Characterization of a New Chiral PAEK Containing 1,1′-Bi-2-naphthyl Moiety

CAO Hui, BEN Teng, WANG Xing, LIU Na, LIU Xin-Cai, ZHAO Xiao-Gang, ZHANG Wan-Jin, WEI Yen

2004, 25(10):  1972-1974. 

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A new chiral poly(aryl ether ketone)(PAEK) containing 1,1′-bi-2-naphthyl moiety was synthesized. The chiral PAEK was characterized by IR, ¹H NMR, GPC and DSC. The chiral behavior of the chiral PAEK was investigated by vibrational circular dichroism(VCD) preliminaryly, and we found it possesses the chiral feature. It would be attempted to be chiral stationary phase to realize chiral separation.

Self-assembed Film from Polyvinylacetal of Formyl-phenyl Ethenyl-pyridium and Its Patterning

WANG Yang, ZHANG Mao-Feng, LI Qi, CAO Wei-Xiao

2004, 25(10):  1975-1977. 

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Polyvinylacetal of 4-[2-(4-formylphenyl)ethenyl]pyridium(PVA-FEP) was synthesized and the layer by layer self-assembly from PVA-FEP as polycation with a series of polyanions was investigated. The multilayer utrathin films formed are photoreactive. Under UV irradiation the [2+2] cycloaddition of the styrylpiridium moieties of PVA-FEP takes place to produce crosslinking net works in the layers of the film. And the stability of the irradiated film toward polar solvents enhances greatly. The patterning of the film has been realized by selective UV exposure of the film through a photomask then developing in saturated sodium dodecyl sulfate aqueous solution.

SAXS/WAXS Studies on Structure of Spherical Micelles Formed by Poly(oxyethylene)/poly(oxybutylene) Block Copolymers in n-Hexane

XU Jun-Ting, LIANG Guo-Dong, Mai Shao-Min, Ryan Anthony J.

2004, 25(10):  1978-1980. 

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The structure of micelles formed by two poly(oxyethylene)/poly(oxybutylene) block copolymers, E₇₆B₃₈ and E₁₅₅B₇₆, in n-hexane at 50 ℃ was studied by synchrotron Small Angle X-ray Scattering(SAXS) and Wide Angle X-ray Scattering(WAXS). Spherical micelle with a crystalline core was observed for E₁₅₅B₇₆. E₇₆B₃₈ also formed spherical micelles, but the core was amorphous. The radius of the core(R), the length of the amorphous chain in the shell(L) and the number of association(N) were obtained by fitting the SAXS data with the model of a spherical core attached with Gaussian chains. The result showed that the E block exhibited multiple folds. The B block tended to be more coiled and the area occupied by per chain was larger in the micelles of E₁₅₅B₇₆, which are favorable to the formation of spherical micelles.