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10 September 2016, Volume 37 Issue 9

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Cover and Content of Chemical Journal of Chinese Universities Vol.37 No.9(2016)

2016, 37(9):  0-0. 

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Articles: Inorganic Chemistry

Influence of Solvent on Structure of Ni(Ⅱ) Metal-organic Frameworks^†

GAO Lijuan, WANG Li, WANG Shengyan, JING Shubo

2016, 37(9):  1589-1595.  doi:10.7503/cjcu20160289

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Solvent is an important influence factor in the self-assembly process of metal-organic framworks. In this article, using the semi-rigid 4-imidazol-1-yl-benzoic acid organic ligand(HL) and Ni(OAc)₂·4H₂O, three novel metal organic frameworks, [Ni(L)₂]_n·DMF(1), Ni(H₂O)₂(L)₂(2) and Ni(OCH₃)₂(HL)₂(3), were synthesized in different solvents. When the solvent was N,N-dimethyl formamide, compound 1 was synthesized, showing a 3D framework with one dimensional diamond channels. Using DMF/H₂O as the solvent, compound 2 was prepared, it exhibits a 2D layer structure with water molecules as terminal ligands, the adjacent layers are linked through hydrogen bonding interactions to form a 3D supramolecular structure. Compound 3 was synthesized in CH₃OH, showing a 2D layer structure. Compounds 1—3 display antiferromagnetic property and exhibit a couple of obvious redox peaks in a certain range of potential, respectively.



Synthesis and Characterization of Composite H₆P₂Mo₁₈O₆₂/Zn(BDC)(Bipy)_0.5 and Its Adsorption Activity for Methylene Blue^†

GONG Wenpeng, TIAN Chaoqiang, DU Xiaogang, YANG Shuijin

2016, 37(9):  1596-1604.  doi:10.7503/cjcu20160253

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By employing the H₆P₂Mo₁₈O₆₂, terephthalic acid(H₂BDC), 4,4'-bipyridine(Bipy) to assemble with Zn²⁺ ion, a three-dimensional(3D) metal organic framework composite, named H₆P₂Mo₁₈O₆₂/Zn(BDC)(Bipy)_0.5, was synthesized. The composition, structure, morphology, stability and toleration of H₆P₂Mo₁₈O₆₂/Zn(BDC)(Bipy)_0.5 were characterized by X-ray powder diffraction pattern(XRD), Fourier transform infrared(FTIR) spectrum, scanning electron microscopy(SEM), thermogravimetric(TG) analysis and N₂ adsorption-desorption analysis. The adsorption of methylene blue(MB) onto H₆P₂Mo₁₈O₆₂/Zn(BDC)(Bipy)_0.5 in aqueous solution was studied. The effects of the experimental parameters including the temperature, the initial pH value and initial concentration of methylene blue solution were discussed. The experimental data could be well described by the Langmuir equations and pseudo-second-order kinetic model. The adsorption process of methylene blue on the composite was spontaneous and exothermic. Furthermore, we also explored the adsorption properties of H₆P₂Mo₁₈O₆₂/Zn(BDC)(Bipy)_0.5 to methyl violet, malachite green, rhodamine B, and methyl orange. The results indicated that this new absorbent showed better adsorption performance towards cationic dyes.



Investigation on Stability of Perovskite Semiconductor CH₃NH₃PbI₃ by In-situ FTIR Spectroscopy^†

LIU Yang, FU Xianwei, ZHAO Tianyu, LIAN Gang, DONG Ning, SONG Side, WANG Qilong, CUI Deliang

2016, 37(9):  1605-1610.  doi:10.7503/cjcu20160179

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Perovskite hybrid semiconductors CH₃NH₃PbX₃(X=Cl, Br, I) have attracted much interests of the chemists and material scientists due to their advantages including facile preparation, low cost and excellent optoelectronic properties. However, the poor stability of these hybrid semiconductors severely frustrated their practical applications, thus it is very important to investigate their decomposition process and explore the new route to improve their stability. Here we investigated the thermal decomposition process of CH₃NH₃PbI₃ using an in-situ Fourier transformation infrared(FTIR) spectrometer. It was found that the stability of CH₃NH₃PbI₃ was rather sensitive to the existence of oxygen, it began to decompose at 150 ℃ when 1%(volume fraction) oxygen was introduced into the nitrogen atmosphere. In comparison, its decomposition temperature strikingly increased to 250 ℃ when it was heated in pure nitrogen of atmospheric pressure. It was rather surprising that the decomposition temperature of CH₃NH₃PbI₃ further increased to 270 ℃ when the pressure of nitrogen increased to 4.0 MPa. This phenomenon reveals that the thermal stability of CH₃NH₃PbX₃ should be greatly improved by applying an even high pressure, thus the post-treatment of photovoltaic devices could be performed at much higher temperature and even better performance can be anticipated.



Analytical Chemistry

Fluorescence Detection of Au(Ⅲ) Based on Carbon Nitride Nanoparticles^†

ZHUANG Qianfen, CAO Wei, WU Qi, NI Yongnian

2016, 37(9):  1611-1615.  doi:10.7503/cjcu20160401

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A fluorescence sensor for Au(III) detection was constructed on the basis of the fluorescence quenching of carbon nitride nanoparticles by Au(Ⅲ). The experimental results displayed that the Au(Ⅲ) sensor gave a linear range of 0.05—11.0 μmol/L with a detection limit(S/N=3) of 22.6 nmol/L. Moreover, the fluorescence sensor possessed a high selectivity for Au(Ⅲ) detection, and could be applied for Au(Ⅲ) detection in lake samples.



High-sensitive Fluorescent Enhancement Detection of Hg(Ⅱ) Ions Based on Poly(thymine)-templated Copper Nanoclusters^†

LI Ting, CAO Zhong, LI Panpan, HE Jinglin, XIAO Hui, YANG Chan

2016, 37(9):  1616-1621.  doi:10.7503/cjcu20160319

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A rapid sensitive fluorescent sensor was developed for Hg(Ⅱ) ions detection based on the specific thymine-Hg²⁺-thymine structure and photoluminescent property of DNA copper nanoclusters. Upon the addition of Hg²⁺, poly thymine single strand DNA(P1) is transformed into double strand DNA through the formation of T-Hg²⁺-T configuration. Sodium ascorbate is effective to reduce Cu²⁺ to Cu⁰, and this reduction process is accompanied by formation of intermediate Cu⁺. However, Cu⁺ has a strong binding site within hydrogen-bonding moieties in the helix of dsDNA which facilating Cu⁰ gathered in dsDNA to form stronger fluorescent copper nanoclusters than ssDNA copper nanoclusters, and these changes in fluorescence intensity of DNA-CuNCs are allowed for sensitive analysis of Hg(Ⅱ) ions. Satisfactory linear relationship and detection limit were obtained. The resulting calibration plots exhibited good linear correlations in the range from 1.0 nmol/L to 10 μmol/L for Hg(Ⅱ) ions, and the detection limits of Hg(Ⅱ) ions was 0.4 nmol/L. The proposed method was highly selective and other metal ions have no interfering effects on the determination. Moreover, satisfactory results were obtained while the proposed method was applied to determination of Hg²⁺ in real lake samples.



Analysis of Antigenic Determinant Glycans of Peanut Allergy Glycoprotein Ara h1 by Mass Spectrometry^†

PENG Yifang, WANG Chengjian, WANG Jingjing, LI Lingmei, JIN Wanjun, QIANG Shan, SHI Hongdan, ZHANG Ying, HUANG Linjuan, WANG Zhongfu

2016, 37(9):  1622-1628.  doi:10.7503/cjcu20160147

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Peanut seed total protein and glycoprotein Ara h1, which can cause allergic reactions, were chosen as the target materials in this study. Firstly, the glycans were released and labeled with 1-phenyl-3-methyl-5-pyrazolone(PMP) by recently developed “one-pot” method. Subsequently, the glycans were fractionated and enriched through C18 solid phase extraction column. Finally, the obtained glycans were analysed by electrospray ionization mass spectrometry(ESI-MS), MSⁿ and Hydrophilic interaction liquid chsomatography-mass spectrometry(HILIC-MS). The results indicated that Ara h1 has ten N-glycans, including seven high-mannose type, two ones with xylose modification, and one allergenic core α1,3-fucosylated N-glycan, the content of which is 12.45% of total glycans.



Organic Chemistry

TiO₂ Nanoparticles-catalyzed One-pot Synthesis of Quinazolino[2,1-b]phthalazin-8-one and 3-Acylamino Isoindolo[2,1-a]quinazoline Derivatives^†

ZHANG Jin, LIU Jia, MA Yangmin, YANG Xiufang, CHENG Pei, FAN Chao, LU Ping

2016, 37(9):  1629-1635.  doi:10.7503/cjcu20160292

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An efficient and simple one-pot method was developed for the synthesis of two kinds of N-fused quinazolinone derivatives using nano TiO₂ particles as catalyst from isatoic anhydride, 2-carboxy benzaldehyde, hydrazides or aromatic hydrazines. Six quinazolino[2,1-b]phthalazin-8-ones and ten 3-acylamino isoindolo[2,1-a]quinazolines were obtained in excellent yields, and the reaction refluxed in aqueous ethanol were environmentally friendly. Attractive features of this methodology were its versatility, mild condition and high efficiency in creating two different structures in a single operation.



Kinetics of the Chemical Hydrolysis and 3D-QSAR Study of 5-Substituted Benzenesulfonylurea Compounds^†

WANG Meiyi, MA Yi, WANG Haiying, CAO Gang, LI Zhengming

2016, 37(9):  1636-1642.  doi:10.7503/cjcu20160257

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The hydrolysis of 9 new 5-substituted benzenesulfonylurea compounds with good herbicidal activity under acidic, neutral and alkaline pH conditions was investigated in laboratory studies. HPLC-MS was used to identify degradates and to study the pathway of hydrolysis. Comparative molecular field analysis(CoMFA) method was applied to the study of the three-dimensional quantitative structure activity relationship(3D-QSAR) on the relationship between the structure of the 5-substituted benzenesulfonylurea compounds and the half-life of hydrolysis. The results showed that the hydrolytic degradation of 5-substituted benzenesulfonylurea followed first-order kinetics. It was easier to be hydrolyzed in acid buffer solutions. Acid-catalyzed cleavage of the sulfonylurea bridge was the first step of degradation, and thus produces 5-substituted benzene sulfonamide and amino-heterocyclic. Amide group further hydrolyzed producing the compound c(6-amino saccharin) and d(saccharin). The 5-substituted benzenesulfonylurea compounds hydrolyzed significantly faster than the parent compounds, Monosulfuron-methyl and Metsulfuron-methyl, under the same conditions. The hydrolysis rate decreased with the increase of the number of alkyl carbon atoms on the amide group and the increase of the volume of the alkyl group. The CoMFA model was able to predict the hydrolysis half-life of this series of compounds.



Construction of Isopeptide Bridge-tethered NHR-trimeric Coiled-coil in MERS-CoV Membrane Fusion Protein^†

ZHENG Xi, LIANG Guodong, WANG Chao, LIU Keliang

2016, 37(9):  1643-1648.  doi:10.7503/cjcu20160237

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In Middle East respiratory syndrome coronavirus(MERS-CoV) infection, the formation of a coiled-coil six-helical bundle(6-HB) between three C-terminal heptad repeats(CHRs) and an N-terminal heptad repeat(NHR) trimer of the MERS-CoV spike protein S2 subunit provided the energy necessary for virus-cell membrane fusion. Mimicry of the NHR-helical trimers in the MERS-CoV membrane fusion protein for the discovery of antiviral therapeutics hampered because of the strong aggregation properties of synthetic NHR-based peptides taken out of their parent protein structure. Herein, the article presents an efficient strategy to recapi-tulate MERS-CoV NHR α-helical trimers via combining the concepts of grafting the NHR-derived peptides onto an exogenous trimerization motif with stabilization of the trimeric oligomers through isopeptide bonds. The covalent bridge was introduced by an acyl transfer reaction between lysine and glutamic acid in specific amino acid sites with thio-easter modified. The designed isopeptide bridge-stabilized chimeric trimers has strong potential for the development potent MERS-CoV fusion inhibitors.



Design, Synthesis and Biological Activity of Novel Substituted Diamides Derivatives Containing Thiophene Ring

LI Lin, LI Miao, CHAI Baoshan, YANG Jichun, SONG Yuquan, LIU Changling

2016, 37(9):  1649-1654.  doi:10.7503/cjcu20160145

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To discover novel diamide derivatives with high insecticidal activity, a series of new substituted diamide derivatives(1—3) containing thiophene ring was synthesized by introducing thiophene ring to diamide derivatives utilizing intermediate derivatization methods(IDM). The compounds were identified by ¹H NMR, IR and elemental analysis. Preliminary bioassays indicated that compound 1 exhibited excellent insecticidal activities against Plutella xylostella and showed 100% mortality at 600 mg/L. Compounds 1a and 1e showed above 60% mortality at 20 mg/L. Compounds 2 and 3 attained by changing the pyrazole ring in diamide derivatives have no insecticidal activity, which illustrated that pyrazole ring in diamide derivatives is very important.



Radiolabeling of DNA Bipyramid Nanostructures^†

LI Jianbo, WANG Xuemei, BAO Baoliang, HE Yulin, WANG Xiangcheng, ZHANG Guojian, BAI Xia, LIU Lei

2016, 37(9):  1655-1659.  doi:10.7503/cjcu20160407

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DNA bipyramid nanostructures were radiolabeled with fluorine-18 through click chemistry. Reactant concentration, catalyst dosage, reaction time, temperatureand reaction frequency in the CuAAC reaction were studied. DNA bipyramid nanostructures were also radiolabeled with technetium-99m through stannous chloride lableling method. The results showed that it was not a good idea to radiolabel DNA bipyramid nanostructures with fluorine-18 through click chemistry. At the same time ^99mTc-DBNs were successfully prepared. Radioactive molecular imaging probes would be obtained based on the nanoplatforms of DNA bipyramid nanostructures.



Physical Chemistry

Density Functional Theory Studies on the CO₂ Absorption by 1-Ethylamine-3-methylimidazolium Tetrafluoroborate^†

ZHANG Hui, ZHANG Hongmei, WANG Lianjun, SHEN Jinyou

2016, 37(9):  1660-1668.  doi:10.7503/cjcu20160337

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CO₂ absorption mechanism by ionic liquids 1-ethylamine-3-methylimidazolium tetrafluoroborate, which was formulated as [NH₂e-mim][BF₄], was described via density functional theory(DFT). The structure of ionic liquids [NH₂e-mim][BF₄], their reaction intermediates, transition states and products, were optimized using the B3LYP/6-311++G(d, p) basis method, with the optimized configuration parameters, vibration frequencies and thermodynamics data obtained. Furthermore, the natural bond orbital atomic charge assignments were also calculated via the natural bond orbital(NBO) method. The computational results demonstrated that the divalent cation [NH₃e-mim]²⁺, which was produced by the autoprotolysis of cation [NH₂e-mim]⁺, could be easily combined with anion [BF₄]^-, with stronger ionic bond formed. According to the calculation results of standard Gibbs free energy(ΔG ^0—) and enthalpy(ΔH ^0—), it could be inferred that the absorption of CO₂ onto ionic liquids [NH₂e-mim][BF₄] was step by step, in accordance with the theoretical molar ratio of 2:1. During the absorption process, the energy barrier of 52.51 kJ/mol should be overcome for proton transfer reaction.



Effect of Aspect Ratio of the Dye Molecule on the Properties of Dye Sensitized Solar Cells^†

REN Siyao, ZHOU Xueqin, LIU Dongzhi, JIANG Kejian, LI Wei, WANG Lichang, WANG Tianyang

2016, 37(9):  1669-1677.  doi:10.7503/cjcu20160302

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Three dyes, 2-cyano-3-[2-(4-{2-[4-N,N-bis(4-methylphenyl)aminophenyl]vinyl}-phenylamino)-pyrimidin-5-yl]-acrylic acid(MTPA-Pyc), 2-cyano-3-(4-{2-[4-N,N-bis(4-methylphenyl)aminophenyl]vinyl}-phenyl)-acrylic acid(MTPAcc), and 2-cyano-3-[4-N,N-bis(4-methylphenyl)aminophenyl]-acrylic acid(MTPAc), that have different aspect ratios were studied for their performances as sensitizer in a dye sensitized solar cell(DSSC). The effects of solvent, the amount of dye molecules adsorbed on the surface of TiO₂, and dye aggregation were investigated. The results show that MTPAcc has the most suitable aspect ratio among the three dyes with the highest and best photovoltaic properties. Polariry of absorption solvents can influence not only the absorbed amount of dyes at TiO₂ but also the dye aggregation. MTPA-Pyc with a large aspect ratio exists in H-aggregation in tolene and tetrahydrofuran, whereas J-aggregation in acetonitrile. MTPAcc was found with high absorption amount at TiO₂ but without aggregation, resulting in the best photovoltaic properties of corresponding DSSC with the incident photon-to-current efficiency(IPCE) of 84% at 490 nm and the photoelectric conversion efficiency(η) of 5.72%. Therefore, the aspect ratio of dye sensitizers is significant for the photovoltaic properties of DSSC.



Spectroscopic Properties of LH2 from Thermochromatium tepidum in Liposome and Detergent Micelles^†

HUO Yilin, SHI Ying, WANG Qinyue, LI Luoyuan, YU Longjiang, WANG Peng, ZHANG Jianping, WANG Zhengyu

2016, 37(9):  1678-1685.  doi:10.7503/cjcu20160277

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By the use of dynamic light scattering(DLS), transmission electron microscopy(TEM), UV-Vis and resonance Raman spectroscopy, the properties of LH2 from Thermochromatium(Tch.) tepidum in two detergent micelles and in liposome were studied, respectively. The results show that in LH2-liposome the conformation of spirilloxanthin, an incorporated longer chain carotenoid, is obviously different from that in detergent micelles. The charge state of the terminal groups of detergents or lipids is the key factor affecting the B850 absorption. Generally, the calcium ions cause red-shift of the B850 absorption and hyperchromicity, while the proton has the opposite effect. Based on the amino acid sequence analysis, several amino acid residues on the C-terminus of α apo-protein were proposed to constitute the potential binding site for the calcium ion and proton. Such Ca²⁺- and H⁺-regulated changes of B850 absorption might be an adaptive mechanism to the living environment for this species.



Theoretical Studies on the Effect of Amino Acid Side Chains on Hydrogen Bonding for G:C in Aqueous Solution^†

ZHAO Jian, DU Jing, LIU Shuo, YANG Zhongzhi, ZHAO Dongxia, LIU Cui

2016, 37(9):  1686-1693.  doi:10.7503/cjcu20160270

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Quantum chemical method was employed to study the hydrogen bond interaction between the amino acid side chain(AASC) analogues and G, C bases, as well as GC base pair in gas and aqueous solution. B3LYP/6-31+G(d,p) was carried out to optimize the complex structures. Moreover, MP2/aug-cc-pVDZ was performed to calculate the energies, natural bond orbital(NBO) charges and second order stabilization energies of these complexes. It demonstrates that hydrogen bond interaction between AASC analogues and bases or base pair can be dramatically weakened in aqueous solution, compared with in gas. For the complexes of AASC analogues with positive charge along with the base or base pair, the difference of their hydrogen bond energies between in gas and aqueous solution is 50.63—146.48 kJ/mol, whereas 0.17—24.94 kJ/mol for neutral AASC analogues. The value of charge transfer is proportional to the hydrogen bonding energy, the more the charge transfer, the more stable the complex. The second-order stabilization energies are inverse proportional to the hydrogen bonds, and the second-order stabilization energies of gas divide ones of aqueous solution is approximately to the value of charge transfer in two phases. It is explicitly shown that aqueous solution has an extremely large impact on hydrogen bonding in these systems.



CuCoCe Catalysts Supported on Carbon Nanotubes for Higher Alcohol Synthesis from Syngas^†

YOU Xiangxuan, FAN Jinchuan, HUANG Wei, ZHOU Youzhi, WEI Junyi

2016, 37(9):  1694-1700.  doi:10.7503/cjcu20160185

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A series of CuCoCe catalysts was prepared by co-impregnation method using different carbon nanotubes as support. In order to improve alcohol synthesis property, the effects of the length and carboxyl group of carbon nanotubes on CuCoCe catalysts were investigated. The catalysts were characterized by X-ray diffraction, N₂ adsorption-desorption, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed that the catalyst supported on carbon nanotubes of 0.5—2 μm with 2.0%(mass fraction) carboxyl group had highest space-time yield(783.72 mg·\begin{array}{c}{g}_{\mathit{cat}}^{-1}\end{array}·h^-1) and the selectivity of C₂₊OH reached 82.71%. The study showed that the short nanotubes can promote more metal particles into the interior of carbon nanotubes and make activity components disperse uniformly, which can significantly improve the conversion of CO and the space-time yield of alcohols. Existence of carboxyl group on carbon nanotubes can enhance the interaction between active metal and support, which can remarkably increase the selectivity of C₂₊OH.



Electrochemical Electron Transfer and Crystallization Process of Uranium(Ⅵ) in Sodium Salt Solution^†

ZONG Meirong, HE Huichao, DONG Faqin, HE Ping, SUN Shiyong, LIU Mingxue, NIE Xiaoqin

2016, 37(9):  1701-1709.  doi:10.7503/cjcu20160171

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Electrochemical beheaviors of uranium(VI) was investigated with cyclic voltammetry and chronoamperometry(CV). The reduction of U(Ⅵ) was analyzed by potentiostatic electrochemical and the kinetics was investigated with electrochemical impedance spectroscopy(EIS). In addition, crystallization of U(Ⅵ) were analyzed by X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy-dispersive spectrometry(EDS). The results indicated that the reduction processes of U(Ⅵ) to U(Ⅳ) was significantly in fluenced by the pH value of solution, with the pH value changed from 3.87 to 4.50, the cyclic voltammetry showed that the reduction of U(Ⅵ) to U(Ⅳ) was in a manner of two-step one-electron process with a diffusion-controlled reaction mechanism. The cyclic voltammetry results presented a constant potential reduction method for removing U(Ⅵ) from aqueous solution, and the reduction efficiency can reach 90%. At a constant potential, U(Ⅵ) mainly crystalized into solid phases in the forms of UO₂ and (UO₂)₆O₂(OH)₈·6H₂O. These results could provide a basis for removing and collecting U(Ⅵ) from solution.



Adsorption-desorption of Hydrogen Bonding Fluid Confined in a Spherical Cavity: the Role of Surface Regulation^†

LI Jiangtao, LIU Shujing, GU Fang, WANG Haijun

2016, 37(9):  1710-1715.  doi:10.7503/cjcu20160078

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The effect of surface regulation on the phase behavior of hydrogen bonding(HB) fluid confined in a nano-spherical cavity was investigated by phase equilibrium thermodynamics. We tried to reveal the important role of cavity surface playing in the adsorption-desorption transition of confined HB fluid when the fluid-surface interaction is a square-well potential. In this study, density functional theory for classical fluids was used together with the modified fundamental measure theory. It was found that the cavity surface could give rise to significant effects on the critical temperatures, critical densities and phase regions of layering transition and capillary condensation. As a result, one can regulate the phase equilibria and aggregated state of the HB fluid by changing the strength and range of fluid-surface interaction and the radius of spherical cavity. It is expected that the present study is helpful to design related adsorption materials or to study the phase behavior of nano-fluids.



Extraction Interfacial Properties of La³⁺ from HNO₃ System with TODGA^†

WEI Bing, CUI Yu, MA Shoutao, YANG Quanning, SUN Guoxin

2016, 37(9):  1716-1721.  doi:10.7503/cjcu20160037

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The interfacial properties of La³⁺/HNO₃/N,N,N',N'-tetraoctyl diglycolamide(TODGA)/dilute system were studied by the drop volume method, including the effect of TODGA concentration, equilibrium time, types of diluents, La³⁺ concentration system temperature, ionic strength and acidity on the interfacial properties. It was found that: (1) the interfacial saturated adsorption time is about 120 s in this system; (2) the interfacial tension are different with the different TODGA concentrations, so the interfacial saturated adsorption species may exist differences; (3) the decrease of the interfacial tension is bigger in small polarity dilute system, such as octane>cyclohexane>benzene>toluene; (4) because of the protonation effect for TODGA, the interfacial activity enhanced with the increasing of HNO₃ concentration, and reduced the interfacial tension; the presence of NaNO₃ reduced the concentration of free TODGA molecules at the interface, and let the interface tension increased.



Polymer Chemistry

Structure and Properties of Starch/Poly(butylene succinate) Blends Plasticized by [BMIM]Cl^†

LEI Bei, LUO Hui, SHI Mengke, ZHANG Xi

2016, 37(9):  1722-1727.  doi:10.7503/cjcu20160385

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In order to study the effect of the ionic liquid on starch/poly(butylene succinate)(PBS) blends and reduce the brittleness of the blends, starch/PBS blends plasticized with ionic liquid([BMIM]Cl) were prepared by melt blending. Infrared absorption spectroscopy(IR), scanning electron microscopy(SEM), thermal gravimetric analysis(TGA), X-ray diffraction(XRD) and mechanical test were adopted to study the effects of [BMIM]Cl on the structure and performance of starch/PBS blends. The results showed that [BMIM]Cl can form strong interactions between starch and PBS molecules, thus disrupting the inter and intra hydrogen bonding of starch and PBS chains and also destroying the crystal structure, which improved the interfacial bonding strength and compatibility between starch and PBS. The glass transition temperature(T_g), crystallization point(T_c), cold crystallization temperatures(T_cc) and crystallinity(X_c) of starch/PBS blends declined with addition of [BMIM]Cl, that means the intermolecular forces in PBS were weakened by the incorporation of [BMIM]Cl and the activity of chain segments were enhanced; furthermore, the ordered arrangement of PBS main chain in crystalline region could be disturbed, owing to the specific interactions between PBS and [BMIM]Cl. However, the thermal stability of the blends could not be affected of [BMIM]Cl. Meanwhile, with addition of [BMIM]Cl, the tensile strength and elastic modulus decreased, while the elongation at break increased and the brittleness of starch/PBS blends reduced significantly, which indicated that strong interaction and good compatility occured in starch/PBS blends.



Characterization and Property of Sulfonated Polyacrylamide/triethanolamine Supramolecular System^†

ZHU Yangwen, LIU Ge, CAO Xulong, SONG Xinwang, CHEN Yong, LIU Yu

2016, 37(9):  1728-1732.  doi:10.7503/cjcu20160274

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Polymer flooding technology is one of the preferred “enhanced oil recovery”(EOR) technologies used for improving oil recovery. Among the various chemical reagents for polymer flooding technology, polyacrylamide has attracted more and more attention. To explore the improving effect of triethanolamine(TEA) on sulfonated polyacrylamide(SPAM), the interaction of negatively charged sulfonated polyacrylamide with triethanolamine and the structure of SPAM/TEA supramolecular system were investigated in aqueous solution and mineralized water by means of transmission electron microscopy(TEM), viscosity, dynamic light scattering(DLS), zeta potential and rheological experiments. The results indicate that, through the cooperative contribution of electrostatic and hydrogen bond interactions, SPAM and TEA can form a large supramolecular assembly with an average diameter of 780 nm measured by DLS. Significantly, the formation of SPAM/TEA supramolecular system can efficiently improve the viscosity and rheological properties of sulfonated polyacrylamide. In addition, the nearly neutral zeta potential of SPAM/TEA supramolecular system can decrease the affect of Ca²⁺ and Mg²⁺ cations in the mineralized water.



Enzymatic Polymerization of Phenols Catalyzed by Chloroperoxidase in the Presence of Ionic Liquids/Quaternary Ammonium Salts^†

WANG Shengjie, LIU Lixia, JIANG Yucheng, HU Mancheng, LI Shuni, ZHAI Quanguo

2016, 37(9):  1733-1739.  doi:10.7503/cjcu20160236

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A green enzymatic approach for the synthesis of phenol polymersfrom substituted phenols monomer by chloroperoxidase(CPO)-catalyzed H₂O₂-oxidation was proposed in this paper. The yield and thermal stabi-lity of polymers of p-methyl phenol, p-ethyl phenol, p-propyl phenol, p-phenyl phenol and p-hydroxy-cinnamic acid were studied based on the presence of imidazolium-based ionic liquids(ILs) or quaternary ammonium salts(QAS), the effect of structure of the substrates and the reaction microenvironment. The results showed that the introduction of little amount of ILs/QAS can improve the production of polymerization of phenols efficiently, in which ILs/QAS with bigger cation group and shorter hydrophobic chain was much more effective, while the influence of ILs/QAS amount on polymerization of phenols showed a “ball type” pattern. Moreover, it was found that p-substituted phenol and electron-donating group were more beneficial to the increase of yield and thermal stability of phenol polymers compared to o-substituted phenol and electron-withdrawing group. However, the steric hindrance was increased with the increasing size of substituent group, which was not beneficial to the polymerization of phenols. The pH value should be controlled as weak acid or even near-neutral to avoid competitive side reaction, while the adding of H₂O₂ should be in a batch type to suppress the oxidative damage of heme caused by the instantaneous concentrated H₂O₂. The mechanism of polymerization was also analyzed and proposed based on the characteristics of structure of CPO active site.



Preparation of Gigaporous Microspheres Through Atom Transfer Radical Polymerization^†

YU Tian, XU Chengnan, YU Yuan, ZHAO Feifei, PAN Yiting, LIU Cai, HUANG Yongdong, ZHANG Rongyue

2016, 37(9):  1740-1743.  doi:10.7503/cjcu20160196

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The gigaporous microspheres based on a copolymer of glycidyl methacrylate and ethylene dimethacrylate were prepared by atom transfer radical polymerization(ATRP). The microspheres were characterized by Fourier transform infrared spectrometer, scanning electronic microscopy and mercury intrusion porosimetry. The results indicated that the microspheres by ATRP showed larger size pore and surface than those by conventional free radical polymerization(CFRP). It was observed from the morphology of the microspheres that the smaller size of particles(100—400 nm) formed the skeleton of microspheres by ATRP than CFRP method(1000 nm). Meanwhile the size of these particles by ATRP was well-distributed in comparison with CFRP. These microspheres by ATRP showed good potential in rapid separation of proteins.



Mechanical Strength and Swelling Behavior of Fatty Alcohol Polyoxyethylene Acrylate Hydrophobic Associated Hydrogels^†

GAO Tingting, LI Zhiying, GAO Ge, LIU Fengqi

2016, 37(9):  1744-1749.  doi:10.7503/cjcu20160115

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We designed a series of hydrophobic hydrogels(HA-gels) through micellar copolymerization with acrylamide(AM) as hydrophilic monomer, a little amount of fatty alcohol polyoxyethylene acrylate(AEO-AC-n-m: n is the amount of carbon chain, m is the amount of PEG chain, n, m=10, 5; 13, 5; 13, 10) as hydrophobic monomer, and potassium thiosulfate(KPS) as initiator in sodium dodecyl sulfate(SDS) aqueous solution. The “straight HA-gels” prepared by AEO-AC-13-5 with straight carbon chain, possess uniform network structure and higher mechanical properties and can maintain their shapes in still water for 180 d. Conversely, the “branched HA-gels” synthesized by AEO-AC-10-5, AEO-AC-13-10 with various branched carbon chains, show relatively weak mechanical properties and degrade in water within 60 d. More specifically, the maximum broken stress of straight HA-gels is almost 4—5 times higher than branched HA-gels under the same constraints. On the basis of the neo-Hookean equation of the rubber elastic theory, the effective network chain density ν₀ and the molecular weight of the chain length between cross-linking points M_c were evaluated for straight and branched HA-gels.



Fabrication and Characterization of Injectable Polysaccharide-polypeptide Hydrogel Based on Schiff’s Base^†

ZHAO Qi, HE Wanying, DUAN Lijie, ZHANG Yu, YU Shuangjiang, GAO Guanghui

2016, 37(9):  1750-1756.  doi:10.7503/cjcu20160088

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The purpose of gel is applied to body with no toxic. Based on dextran, oxidized dextran(ODEX) with the different oxidation extent was prepared. At the same time, the tri-block polymers poly(lysine)-polyethylene glycol-poly(lysine)(PLL₂₄-PEG-PLL₂₅) was synthesized, which becomes hydrogels through the reaction between the dextran aldehyde groups and the poly-L-lysine amino groups via Schiff’s base formation. The storage modulus, degradation time of gel, and release of doxorubicin(DOX) were characterized. The results showed that gel strength increased gradually with the increasing density of aldehyde in ODEX, and the maximum storage modulus was 3100 Pa. The rheological test indicates that the storage modulus was reduced from 2160 Pa to 1730 Pa, due to the Schiff’s effect between ODEX aldehyde group and DOX amine group. The gel had a long degradation time up to 29 d. Drug release studies showed that DOX released from carrier gel was triggered by the enzyme. In Elastase solution, DOX release rate had reached up to 74.35%. The findings reveal that the hydrogel have promising applications in drug delivery in vivo.