Table of Content

10 April 2020, Volume 41 Issue 4

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Contents

Cover and Content of Chemical Journal of Chinese Universities Vol.41 No.4(2020)

2020, 41(4):  0-0. 

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Review

Research Progress of Photoelectrochemical Technology Applied in Antioxidant Analysis ^†

HAN Fangjie, DAI Mengjiao, LIANG Zhishan, SONG Zhongqian, HAN Dongxue, NIU Li

2020, 41(4):  591-603.  doi:10.7503/cjcu20190651

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In the process of metabolism, the body will produce a large number of oxidation active substances with free radicals as the main formation, and antioxidants can capture and neutralize free radicals in the form of electron transfer, so as to protect the cell from damage, prevent and retard the oxidative deterioration of food. Therefore, it is of great significance for the determination and evaluation of antioxidants capacitance in foods. As a low-cost, simple, quick and sensitive method, photoelectrochemical(PEC) technology can overcome the shortcomings of conventional methods, such as optical method, chromatographic method and electrochemical method. The design of photocatalysis materials is the key of the PEC platform. The review concludes with the progress of the photoelectrochemical platform based on semiconductor materials applied in the analysis of antioxidant capacity in food and the characteristics of various detection systems. In addition, the future research directions are also proposed.



Research Progress of Photo-driven C1 Conversion to Value-added Chemicals ^†

LI Zhenhua, SHI Run, ZHAO Jiaqi, ZHANG Tierui

2020, 41(4):  604-615.  doi:10.7503/cjcu20190641

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We summarized recent progresses of photo-driven C1 chemistry. Latest researches on photo-driven Fischer-Tropsch synthesis, Water-Gas shift, carbon dioxide hydrogenation, methane reforming, and methanol reforming for hydrogen production were systematically reviewed. In addition, the existing problems as well as prospects were also proposed in the research field.



Synthesis of Hierarchical NaX Zeolite and Its CO₂ Adsorption Performance ^†

WANG Yuyao, ZHANG Qiang, YU Jihong

2020, 41(4):  616-622.  doi:10.7503/cjcu20200083

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High-quality hierarchical NaX zeolites with high product yield and high crystallinity were prepared by synergistically using a two-step crystallization process and L-lysine-assisted approach. XRD, SEM, TEM, XRF and N₂ adsorption-desorption tests are used to investigate the influence of L-lysine and crystallization steps on the mesoporosity, crystallinity, and the yield of NaX zeolites. In this synthetic strategy, two-step crystallization favors the generation of mesopores; and L-lysine plays an important role in improving the zeolite crystallinity as well as the product yield. Owing to the high-quality hierarchical zeolite crystals, the as-prepared NaX zeolite exhibits excellent performance in CO₂ adsorption with CO₂ uptake of 154.2 cm ³/g at 273 K and 100 kPa. This green and facile synthetic strategy opens a new way to fabricate high-quality hierarchical NaX zeolites, promising their practical applications in CO₂ adsorption.



Glutathione Sensing: from Colorimetry to Single Particle Spectroscopy Based on Gold NP@MnO₂ Nanosheets Supraparticles

LING Yunyun,LI Li,LIANG Xiurong,XIA Yunsheng

2020, 41(4):  623-632.  doi:10.7503/cjcu20190686

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We herein study glutathione(GSH) sensing by two kinds of assay modes, namely colorimetry and single particle spectroscopy, using the as-prepared hybrid supraparticles made of gold nanoparticles and MnO₂ nanosheets(denoted as AMNS-SPs) as probes. The sensing is based on the selective etching of decorated MnO₂ nanosheets, which causes a substantial blue shift of the localized surface plasmon resonance of the AMNS-SPs. In terms of the two sensing systems, the detection limits are 0.018 μmol/L and 23.2 fmol/L, respectively. To our knowledge, the latter is one of the highest sensitivity for GSH sensing. This favorable performance is attributed to a rather thin thickness of the decorated MnO₂ nanosheets.



Structure-function Relationship of Plant Polyphenols for Promoted siRNA Delivery ^†

SHEN Yang, ZHU Fang, SHEN Wanwan, FAN Qianqian, LI Yiwen, CHENG Yiyun

2020, 41(4):  633-638.  doi:10.7503/cjcu20190694

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Epigallocatechin gallate(EGCG) has demonstrated promising effects in promoting the delivery of siRNA by low molecular weight cationic polymers. EGCG can be further hydrolyzed into (-)-epigallocatechin(EGC) and gallic acid(GA) motifs. EGC and GA also have the effect of inhibiting cancer cells, killing tumor cells, and binding proteins or nucleic acids through the combination of hydrogen bonding and hydrophobic interactions. Herein, this study strives to perform a structure-function relationship investigation of plant polyphenol motifs(EGCG, EGC, and GA) in facilitation of condensation and delivery of siRNA by low molecular weight cationic polymers. It was found that EGCG exhibited the highest efficiency in promoting PLL-mediated siRNA delivery while EGC also showed a promising result, and the latter efficiency can be further improved by tailoring the dose of EGC in the complex.



Self-reduction for the Synthesis of Co Supported on Hierarchically Porous Carbon for Selective Hydrogenation Reaction ^†

HE Xiaoke, LI Xiaoyun, WANG Zhao, HU Nian, DENG Zhao, CHEN Lihua, SU Baolian

2020, 41(4):  639-645.  doi:10.7503/cjcu20190687

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A series of supported cobalt-based nanocatalysts were synthesized by a one-step self-reduction method using cobalt-based organic framework as precursor. The effect of self-reduction of carbonization on the catalytic performance of supported cobalt-based catalysts was studied. This method successfully controlled the hierarchically porous structure of supports and the size of cobalt nanoparticles. The prepared Co-based catalysts had high catalytic activity and product selectivity for selective hydrogenation of 1,3-butadiene. Specially, it was found that the catalyst carbonized at 600 ℃ contained a hierarchically porous structure with large surface area, and a uniform distribution of cobalt nanoparticles without obvious aggregation. Most importantly, the corresponding sample exhibited a rather low 100% conversion temperature at 60 ℃ for selective hydrogenation of 1,3-butadiene, but with butenes selectivity as high as 61%. This work provides a new strategy for the preparation of supported non-noble metal catalysts with high-performance for hydrogenation reactions.



Glass-like Cuprous Iodide Complexes with Photoluminescence Tuning and Two-photon Emission Properties ^†

YIN Shaoyun, ZHANG Luyin, WANG Zheng, PAN Mei

2020, 41(4):  646-651.  doi:10.7503/cjcu20190657

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Eight kinds of glass-like cuprous iodide complexes with Cu₂I₂L₂ configurations were self-assembled from CuI with semi-flexible 3-pebtd ligand with unsaturated π-backbone and bipodal pyridine terminals in different solvents. The complexes were characterized by X-ray single crystal diffraction, X-ray powder diffraction, elemental analysis, and so on. The photophysical properties of the complexes were studied, and the results show that the one-photon emissions of the complexes obtained in different solvents show single fluorescence bands assigning to the halogen to ligand charge transfer( ³XLCT). The luminescent colors of the complexes were adjustable from 492 to 518 nm, and the quantum yield was 33.1%~68.5%. At the same time, these complexes exhibit excellent two-photon emission properties and are expected to be used in the field of biological imaging.



Auto-redox Strategy for the Synthesis of Co₃O₄/CeO₂ Nanocomposites and Their Structural Optimization Towards Catalytic CO Oxidation

JIN Xin, FENG Xilan, LIU Dapeng, SU Yutong, ZHANG Zheng, ZHANG Yu

2020, 41(4):  652-660.  doi:10.7503/cjcu20190649

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A simple auto-redox strategy was successfully used to synthesize Co₃O₄/CeO₂ nanocomposites. These samples were then characterized by means of TEM, XRD, XPS, and so on, to study the influence of reaction parameters on their catalyst activity. The results indicate that the catalytic performance of Co₃O₄/CeO₂ nanocomposites could be optimized by changing the molar ratio of Co/Ce, pH values, reaction and calcination temperatures. The optimal Co₃O₄/CeO₂ nanocomposite could reach a 100% CO conversion at 140 ℃ compared to the others. Moreover its catalytic activity kept stable after cycling, indicating its good stability.



Effect of Phase Behavior of Phospholipids on Lipid Membrane Damage Induced by Graphene Oxide ^†

ZHANG Xiaofei, WU Lie, LI Shanshan, ZHU Manyu, CHENG Xiaowei, JIANG Xiu’e

2020, 41(4):  661-669.  doi:10.7503/cjcu20190645

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The difference among different kinds of phospholipids in biomembrane not only lies in different structures in polar head groups, but also in different alkyl chain structures which lead to different phase states. Phase state of phospholipids plays an important role in cell activities. In this study, phospholipid membranes with different phase states were constructed by using two phospholipids with different phase transition temperatures and adjusting their mixing ratio, to reveal the effect of the phase behavior of the phospholipid membrane on the interaction between graphene oxide and the phospholipid membrane. Results showed that, for the extraction of phospholipid from membrane, graphene oxide exhibited significant phase selectivity, and it selectively extracted phospholipids in fluid phase. More importantly, the extraction effect of graphene oxide on fluid-phase phospholipids was affected by the presence of gel-phase phospholipids in the membrane. The extraction could occur only when the fluid-phase phospholipid molecules accounted for the majority of the phospholipids in the membrane, and only the phospholipids in fluid phase were extracted. Therefore, the extraction effect of graphene oxide on phospholipids in membrane not only had fluid-phase selectivity, but also was regulated by the phase behavior of phospholipid membrane.



New Semiconducting Polymer Nanoparticles for Antibacterial Agent by the Synergetic Effect of Positive Charge and Photothermal Conversion

PAN Guoyong,LI Yawen,MA Lijun,MA Yufan,AI Wenting,WANG Zhenguo,HOU Xinhui,Grigory V·Zyryanov,WANG Zhuo

2020, 41(4):  670-681.  doi:10.7503/cjcu20190715

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Because of the abuse of antibiotics and the emergence of bacterial resistance, the new antibacterial agents are required urgently. Herein, we prepared semiconducting polymer nanoparticles(SP-PPh₃ NPs) with synergistic antibacterial activity due to photothermal properties and positive charge. SP-PPh₃ NPs have broad-spectrum antibacterial properties against Gram-negative Escherichia coli(E. coli) and Gram-positive Staphylococcus aureus(S. aureus). The photothermal conversion efficiency of SP-PPh₃ NPs is 43.8%. Moreover, the positive charge of SP-PPh₃ NPs can adhere to bacteria, which is helpful to transmit heat to bacteria effectively. Under the synergistic effect of heat and positive charge, the antibacterial rates of E. coli and S. aureustreated with SP-PPh₃ NPs are 99.9% and 98.6% in vitro, respectively. In addition, SP-PPh₃ NPs have good biocompatibility and have almost no side effects on the major organs of mice. The bacteria-infected skin wounds on mice can completely heal after 12 d treated with SP-PPh₃ NPs.



Synthesis of InSe Nanoflakes with Near-infrared Photoresponse Grown by Chemical Vapor Deposition ^†

HUANG Wenjuan, HOU Huayi, CHEN Xiangbai, ZHAI Tianyou

2020, 41(4):  682-689.  doi:10.7503/cjcu20190662

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With a graphene-like two-dimensional(2D) layered structure, InSe has a great potential in the application of electronics and optoelectronic devices. Herein, 2D InSe nanoflakes were synthesized via a chemical vapor deposition(CVD) method, and the effect of growth temperature on the crystalline phase, morphology, size and thickness of 2D InSe nanoflakes were studied. Photodetectors based on the as-synthesized 2D InSe nanoflakes were fabricated and its photodetection performance were studied. Under the illumination wavelength of 808 nm, the as-fabricated InSe photodetector exhibited a good near-infrared(NIR) photo-response, showing a photoresponsivity of 1.5 A/W, an external quantum efficiency of 230% and a detectivity of 3.1×10 ⁸ Jones, accompanied with a rise and decay time of 0.5 and 0.8 s, respectively, providing a good prospects for its practical application in NIR photodetectors.



Sulfonated Cellulose Nanofibers Film Supported Nanofiltration Membrane for High-flux and High-rejection Desalination ^†

KONG Jinfeng, ZHU Yuzhang, JIN Jian

2020, 41(4):  690-696.  doi:10.7503/cjcu20190654

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Sulfonated bacterial cellulose(SBC) nanofibers were prepared via oxidation-reduction reaction of NaIO₄ and NaHSO₃. Using this SBC nanofibers film as a new support porous membrane, high performance nanofiltration membrane with highly crumpled polyamide selective layer was prepared via interfacial polymerization between piperazine(PIP) and trimesoyl chloride(TMC). This novel nanofiltration membrane exhibits a superior desalination performance with a high rejection rate of 98.6% and a high permeance of 320 L·m ^-2·h ^-1·MPa ^-1 to 1 g/L Na₂SO₄. The new nanofiltration membrane has a wide application prospect in desalination.



Inorganic Chemistry

Preparation of Hydrophilic FePt Nanoparticles and co-Catalyze Degrade Organic Pollutants ^†

LIU Congyuan, LIU Jia, DU Peiyao, ZHANG Zhen, LU Xiaoquan

2020, 41(4):  697-705.  doi:10.7503/cjcu20190661

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Hydrophilic ultra-small FePt nanoparticles(NPs) stabilized with cysteine were facile synthesized in water phase by one pot method. As-prepared FePt NPs showed good catalytic degradation activity of common organic pollutants in water. NaBH₄ and H₂O₂ were chose as the co-reactant to degrade rhodamine B(RhB), 4-nitrophenol(4-NP) and methylene blue(MB), respectively. The results showed that the degradation rates were more than 90% for three organic pollutants by FePt NPs. At the same time, we focus on the discussion of the collaborative catalytic mechanism between FePt atom pairs, and reveal the difference between the microscopic reaction process and catalytic mechanism in different reaction systems. Moreover, magnetic test results show that FePt catalyst can be collected and reused by external magnetic field, which solves the problem of secondary pollution of the catalyst. This study provides an idea for the design of green catalyst.



Analytical Chemistry

Construction of Cyclodextrin-based Impedance Sensor for Recognition of L-Cysteine ^†

FU Kefei, LIAN Huiting, WEI Xiaofeng, SUN Xiangying, LIU Bin

2020, 41(4):  706-715.  doi:10.7503/cjcu20190584

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By means of quantum chemical calculation, the supramolecular interaction between the γ-cyclodextrin(γ-CD) as the host and the L-cysteine(L-Cys) oxidation product as the guest was simulated from the molecular level. The weak interaction energy(E_L) between γ-CD and L-Cys oxidation product reaches -12.6 eV, which is 3.7 times different from the interaction between γ-CD and D-Cys oxidation product(E_D=-2.7 eV). Their intramolecular hydrogen bonds exist nearly doubled difference. Based on the theoretical simulation, an γ-CD modified impedance sensor was constructed for sensitive and specific impedance identification of L-Cys. Using potassium ferricyanide(Ⅱ/Ⅲ) as the redox probe, the electrochemical transfer impedance(R_et) linearly changed with the concentration of L-Cys between 0.1 μmol/L and 1.0 μmol/L(stage one), and from 1.0 μmol/L and 6.0 μmol/L(stage two), with the detection limit of 74 nmol/L(S/N=3). Compared with the unmodified glassy carbon electrode, the sensitivity for the impedance response of L-Cys has been increased about 19 times. Meanwhile, the selectivity to the thiol-containing structural analog is significantly improved by this cyclodextrin-based sensor, successfully applied for the detection in human serum and drug capsules with average recoveries between 88.9% and 108%. This study establishes a novel, low-cost, simple, quantitative identification method for chiral compounds with weak electrical property, providing a potential strategy for electrochemical analysis of chiral targets.



Organic Chemistry

Design, Synthesis and Biological Activity of 5-Pyrazole Carboxamides ^†

LI Kangming, LI Yansai, YI Yangjie, XU Leitao, YE Jiao, OU Xiaoming, LI Jianming, HU Aixi

2020, 41(4):  716-725.  doi:10.7503/cjcu20190504

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Twenty-three novel 5-pyrazole carboxamides were prepared by condensing two kinds of 5-pyrazolecarboxylic acids with thiazolamides and benzofuranamines. The chemical structures were confirmed by nuclear magnetic resonance(NMR) and mass spectrometry, etc. Quantum chemical calculations, frontier molecular orbitals and molecular van der Waals surface electrostatic potentials were analyzed for compounds B1 and B3. Biological activity screening test results showed that some compounds had excellent Insecticidal activity against Armyworm and Aphis fabae at 500 mg/L concentration, and the lethal rate of compound A1 and B1 against Armyworm was 100%, while compound B3, B4 and C9 showed excellent inhibitory activity towards Aphis fabae with the inhibition rate of 100%, 100% and 95.54%, correspondingly. At a concentration of 25 mg/L, the growth inhibition rates of compound A3 against Alternaria alternata, compound C7 against Gibberella zeae, compounds A1 and A4 against Sclerotonia sclerotiorum were over 50%.



Microwave Assisted Rhodium-catalyzed C—H Activation/cyclization of Diaryl Phosphoramides and Alkynes ^†

ZHOU Chunni, ZHENG Ziang, PENG Wangming, WANG Hongbo, ZHANG Yumin, WANG Liang, XIAO Biao

2020, 41(4):  726-734.  doi:10.7503/cjcu20190571

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A microwave assisted rhodium-catalyzed C—H activation/cyclization of diaryl phosphoramides and alkynes has been developed, and a series of cyclic phosphoramides bearing five fluoro groups could be obtained in moderate to good yields. The optimized reaction conditions were established by examination of solvents, temperature, reaction time and bases. This reaction system was also feasible in a gram-scale reaction without significant decrease in the product yields, and a possible reaction mechanism was then proposed. Moreover, this methology was successfully applied to the synthesis of the novel diamine with the core of fluorine-containing substituted cyclic phosphoramide.



Physical Chemistry

Synthesis and Photocatalytic Hydrogen Evolution Properties of Chitosan Cobalt Complex ^†

CAO Meng, LIU Yang, ZHANG Shangxi, WANG Zhenxi, XU Sheng

2020, 41(4):  735-741.  doi:10.7503/cjcu20190593

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Chitosan-cobalt complex(Cs-Co) was synthesized by one-pot method. The content of Co in Cs-Co is 1.1 mmol/g and Co is positive bivalent. Under the optimized conditions, the total hydrogen production of 18 mg catalyst Cs-Co was 12.7 mL within 80 min, the hydrogen evolution rate was 30258 μmol·g ^-1·h ^-1. By studying the photocatalytic process of Cs-Co and combining with electrochemical method, a possible photocatalytic process and mechanism were proposed.



Controllable Fabrication of Photogenerated Charges Gradient Continuous Transfer Chain to Enhance Photocatalytic Performance ^†

LIU Dongxu, CHEN Xuebing, YANG Xia, ZHANG Jing, CHEN Changdong

2020, 41(4):  742-749.  doi:10.7503/cjcu20190546

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Based on the matched band structure of γ-Bi₂O₃, α-Bi₂O₃, and Bi₄Ti₃O₁₂, the ‘ternary isotype junction’ Bi₄Ti₃O₁₂@α/γ-Bi₂O₃ with gradient energy levels was synthesized in situ by simple immersion method. The results of photocatalytic degradation of high concentration rhodamine B(RhB) and 4-chlorophenol(4-CP) show that, compared with γ-Bi₂O₃ and α/γ-Bi₂O₃, Bi₄Ti₃O₁₂@α/γ-Bi₂O₃ exhibits more remarkable photocatalytic activities. It is worth mentioning that when the mass ratio of Ti/Bi is 0.5%(0.5%Bi₄Ti₃O₁₂@α/γ-Bi₂O₃ sample), the photocatalytic degradation rate for RhB(or 4-CP) is 4.4 times(or 2.2 times) that of α/γ-Bi₂O₃, even 32 times(or 10.4 times) that of γ-Bi₂O₃. The optoelectronic property measurements confirm that greatly improved photogenerated charges separation and transference efficiency has been realized on Bi₄Ti₃O₁₂@α/γ-Bi₂O₃ ternary isotype junction, which is one of the main reasons for the high photocatalytic performance of Bi₄Ti₃O₁₂@α/γ-Bi₂O₃. This paper provides a new way for fabricating high efficiency photogenerated charges transfer chain, then promoting the separation and transference of photogenerated charges, and thus greatly improving the performance of the photocatalysis.



Fabrication of Lamellar Liquid Crystals of Conjugated Linoleic Acid as Drug Delivery Systems ^†

FAN Ye, LI Qian, FANG Yun, XIA Yongmei

2020, 41(4):  750-756.  doi:10.7503/cjcu20190682

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The lamellar liquid crystals in aqueous phase using conjugated linoleic acid(CLA) and its conjugate base sodium conjugated linoleate(SCL) were fabricated, and drug release behavior of the resulted lamellar liquid crystals was investigated. The lamellar liquid crystal phase in the CLA/SCL/H₂O ternary phase diagram was determined by means of polarizing microscopy assisted by visual inspection. The polarized texture, phase parameters and rheological parameters of the lamellar liquid crystals were obtained by polarizing microscope, small-angle X-ray scattering system and rotational rheometer, and the experimental results confirm that the lamellar liquid crystals are suitable for drug delivery system(DDS). The releasing curves of a hydrophilic drug 5-fluorouracil and a lipophilic drug curcumin were measured by dialysis experiments using the drug-loaded lamellar liquid crystals as DDS, and good sustained release abilities for both drugs were provided by the lamellar liquid crystals.



Palladium-based Nanocatalysts Supported on Polybenzoxazine for Aromatic Alcohol Oxidation ^†

HAO Yan, YANG Hua, WANG Xiang, LI Qingyang, ZHAO Pan, TANG Qinghu, SONG Shili, XI Guoxi

2020, 41(4):  757-764.  doi:10.7503/cjcu20190594

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Carbon supported palladium-based nanocatalysts were synthesized via an impregnation-pyrolysis method, based on a spherical polybenzoxazine as support, owing to the interaction between nitrogen groups and metal nanoparticles. Transmission electron microscope(TEM) images of Pd/C catalyst showed that palladium nanoparticles were uniformly distributed over the support with an average size of about 3.5 nm. The cha-racterization results of Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and temperature programmed desorption(CO₂-TPD) analysis, showed that a mount of nitrogen and oxygen functional groups existed on the support. The nitrogen and oxygen atoms might have interactions with Pd atoms, which could effectively immobilize palladium nanoparticles and obtain well dispersed palladium-carbon nanocatalysts. The bimetallic Pd-Au/C and Pd-Pt/C catalysts were prepared via the same method to further enhance the catalytic activity. The average particle size of Pd-Au and Pd-Pt nanoparticles were 4.3 and 4.2 nm, respectively, without an obvious agglomeration, which demonstrated the effective immobilization role of polybenzoxazine support. The catalysts were evaluated by the benzyl alcohol oxidation reaction at 80 ℃ and water as solvent. The Pd₁-Au₁/C catalyst exhibited the highest conversion of >98% within 2 h and the selectivity to benzaldehyde of >99%, revealing the excellent catalytic performances. Moreover, the catalyst could be used for several runs and easily regenerated by calcination. Furthermore, the catalyst could also oxidize aromatic alcohols with different substituents into corresponding aldehydes, such as 4-methyl benzyl alcohol, 4-methoxybenzyl alcohol, 2-methyl benzyl alcohol and so on, providing an excellent catalyst for aromatic alcohol oxidation.



Promoting Effect of Cerous Phosphate on the Phenol Catalytic Transfer Hydrogenation over Nickel Phosphide Catalyst ^†

MENG Fanxing, YU Zhiquan, JING Wenwen, WANG Yao, SUN Zhichao, WANG Anjie

2020, 41(4):  765-764.  doi:10.7503/cjcu20190573

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A series of CePO₄-Ni₃P and Ni₃P catalysts with various Ce/Ni molar ratio were prepared by in-situ H₂ temperature-programmed reduction, and utilized to catalyze the transfer hydrogenation of phenol. The effects of Ce/Ni molar ratio, hydrogen donors, reaction temperature and reaction time on the catalytic perfor-mance were investigated. What’s more, the reaction kinetic parameters were calculated. The reaction results showed that the addition of CePO₄ could significantly improve the phenol conversion. The promoting effect was the most obvious when the Ce/Ni molar ratio was 0.2. 2-Propanol exhibited the best catalytic activity among all the screened solvents. A high cyclohexanol selectivity of 92.0% and phenol conversion of 93.1% could be obtained at 220 ℃ for 6 h over the CePO₄(0.2)-Ni₃P catalyst using 2-propanol as the hydrogen donor and solvent.



Combustion Mechanism Construction Based on Minimized Reaction Network: Hydrogen-Oxygen Combustion ^†

LI Xiangyuan, SHENTU Jiangtao, LI Yiwei, LI Juanqin, WANG Jingbo

2020, 41(4):  772-779.  doi:10.7503/cjcu20190568

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In the construction of detailed combustion mechanisms, the reaction networks become more and more complicated so far, thus the numbers of species and reactions increase seriously. On the other hand, the too large size of the reaction mechanism will make the combustion numerical simulation difficult in practice. In this work, the minimized reaction network method(MRN) based on the principle of chemical simultaneous equilibrium was proposed in order to construct detailed combustion mechanism with minimum number of reaction steps for the given chemical species and applied to hydrogen-oxygen combustion at first. Six independent reactions were determined for an eight-species system. This minimized mechanism in principle is enough to describe the combustion process. However, some global reactions need to be replaced by other reaction steps owing to the lack of the rate constants. In this way, a nine-step detailed mechanism of hydrogen combustion(MRN-C0) was developed. In dealing with the kinetic parameters, the two-parameter Arrhenius equation was adopted to replace the so-called modified Arrhenius equation. Such a treatment guarantees the physics of the activation energy and pre-exponential factor. The reliability of this new method, MRN, has been verified through the numerical simulations of ignition delay time and laminar flame with the nine-step hydrogen combustion mechanism.



Polymer Chemistry

Osteogenesis-promoting Effects of the Electrospun Nanofibers Containing Decellularized Bone Matrix ^†

QIN Chunping, WANG Xianliu, TANG Han, YI Bingcheng, LIU Chang, ZHANG Yanzhong

2020, 41(4):  780-788.  doi:10.7503/cjcu20190524

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Porcine decellularized bone matrix(DBM) was firstly prepared, and then solubilized via pepsin digestion. Solubilized DBM and poly(L-lactic acid)(PLLA) were subsequently processed into PLLA/DBM electrospun nanofibers through eletrospinning technology. The morphology, wettability and mineralization ability of PLLA/DBM electrospun nanofibers were examined, and cytocompatibility and osteogenic differentiation capacity were evaluated by culturing bone marrow mesenchymal cells(BMSCs) on PLLA/DBM electrospun nanofibers. The results showed that cellular components in cancellous bone could be effectively removed after decellularization, as evidenced by the significant decrease in DNA content. The solubilized DBM could be dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol(HFIP) for electrospinning of the PLLA/DBM composite nanofibers formulated at different mass ratios(10∶0, 9∶1, 7∶3 and 5∶5). The obtained PLLA/DBM electrospun nanofibers were demonstrated to be hydrophilic and cytocompatible, and significantly promoted the attachment and osteogenic differentiation of the BMSCs. Furthermore, the presence of DBM facilitated mineral deposition on the nanofiber surface in simulated body fluid(SBF), which suggests its great potential in promoting bonding with the natural bone tissue.



Thermal-oxidative Aging Performance of TBIR Modified NR/BR Vulcanizates in Aircraft Tire Sidewall ^†

GUO Qinrui, SHAO Huafeng, HE Aihua

2020, 41(4):  789-794.  doi:10.7503/cjcu20190540

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The thermal-oxidative aging performance of a new generation synthetic rubber trans-1,4-butadiene-isoprene copolymer rubber(TBIR) in NR/BR vulcanizates was studied. Compared with the NR/BR vulcanizates, the crosslinking density of NR/BR/TBIR vulcanizates with 10 to 20 per hundreds of rubber(phr) TBIR improved significantly as while as the tensile properties changed little. The heat build-up reduced by 2.2—3.4 ℃ and the flexural fatigue resis-tance increased about 100%. The filler dispersion improved and the average aggregate size of the filler reduced. With the increasing of thermal-oxidative aging time, the crosslinking density of vulcanizates increased and then decreased. The crosslinking density of NR/BR/TBIR vulcanizates remained unchanged after 48 h. With the increasing of aging time, the heat build-up first decreased and then increased and NR/BR/TBIR vulcanizates has the lowest heat build-up value. The flexural fatigue lifetime of NR/BR/TBIR was better than NR/BR vulcanizates.



Thermal Expansion Behavior of Amide-containing Polyimide Films with Ultralow Thermal Expansion Coefficient ^†

BAI Lan, ZHAI Lei, WANG Changou, HE Minhui, MO Song, FAN Lin

2020, 41(4):  795-802.  doi:10.7503/cjcu20190563

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A series of amide-containing polyimide i. e. poly(amide-imide) films was prepared from biphenyl tetracarboxylic dianhydride and three diamines comprising diamide groups via two-step thermal imidization method. The effect of amide structure and different substituents on mechanical properties, water absorption, thermal properties and thermal expansion behavior of poly(amide-imide) films were investigated. The results showed that these films exhibited ultrahigh tensile strength up to 280.5 MPa and excellen theat resistance with T_g above 389 ℃. Moreover, these films showed ultralow thermal expansion coefficient(CTE) from -3.05 to -1.74 ppm/℃ in the wide temperature range of 30—300 ℃. The correlation of their thermal expansion behavior with aggregation structures including molecular chain interactions, orientation and packing was systematically studied. It was found that the molecular chains of poly(amide-imide)s were highly oriented along the in-plane direction while densely packed in the out-of-plane direction, because of the hydrogen bonding interactions between amide structures and the rigid linear backbone. That was the main reason for the thermal contraction of films and contributed to their outstanding dimensional stabilities. The aggregation structures of poly(amide-imide)s could be further affected by the substituents in the backbones with different volume and steric effect, resulting in the regulation of CTE values close to zero. It provids a new design thought for the heat-resistant polymer substrates with ultralow CTE for optoelectronic application.



Preparation of High-performance Montmorillonite/hydrogenated Butadiene-acrylonitrile Rubber by Using Electrostatic Interfaces

ZHANG Jihua,WANG Chao,ZAO Weitao,LI Li,LIU Xiaoyan,YANG Yuan,WANG Hao

2020, 41(4):  803-810.  doi:10.7503/cjcu20190595

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After amine-modified montmorillonite(MMT) and methacrylic acid(MA) were mixed to prepare a slurry, they were added to the hydrogenated butadiene-acrylonitrile rubber(HNBR). By thermal vulcanization, MMT/HNBR composites were successfully achieved. The MA-modified MMT/rubber interfaces and their dispersion were carefully investigated by scanning electron microscopy, transmission electron microscopy, small angle X-ray scattering pattern, Fourier transform infrared spectroscopy and vulcameter. Moreover, various properties of rubber composites were analyzed. The experimental results showed that chemical crosslinking networks were developed during vulcanization. In the meantime, MA was in-situ self-polymerized in the rubber matrix and ion pairs were formed between polymethacrylic acid and amine on MMT, which therefore constructed strong electrostatic interfaces between MMT and rubber matrix. The self-polymerization of MA extended interlayer spacing of MMT, leading to a good dispersion of MMT in rubber matrix. MMT with good dispersion and ion interfaces constrained the slippage of rubber chains during stretching, which was proved by the dynamic mechanical properties and stress relaxation at 200%. So the tensile strength and toughness of rubber composites were greatly improved. In addition, the N₂ permeability of rubber composites was reduced, showing a good gas barrier property. Therefore, the preparation of MA/MMT slurry is a simple and convenient method to modify the MMT. We believe that as-prepared MMT/HNBR composites can be used in the rubber products with the requirements of high mechanical and good gas barrier properties.



Visible-light-sensitive Versatile Fluorescent Brightener-based Photoinitiating Systems ^†

ZUO Xiaoling, WU Chong, HUANG Anrong, LUO Jiaolian, LI Zhuyu, WANG Meng, ZHOU Ying, YU Hongna, GUO Jianbing

2020, 41(4):  811-820.  doi:10.7503/cjcu20190596

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Five kinds of commercial fluorescent brighteners containing different fluorophores were investiga-ted, i.e. 4,4'-bis(2-benzoxazolyl)stilbene(BBS), diethylamino-4-methylcoumarin(C 1), bis-(triazinylamino)-stilbene disulphonic(CBUS 450), 4,4'-bis(2-sodium sulphonate styryl)biphenyl(CBS X) and 1,4-bis(2-benzoxazolyl)naphthalene(OB 7), the two-component photoinitiating systems including these fluorescent brighteners and diphenyliodonium hexafluorophosphate(IOD) and the three-component photoinitiating systems including these brighteners, IOD and optionally N-vinyl carbazole or amine were formed, respectively, both of them photoinitiated the free radical photopolymerization for the preparation of polyacrylates and the concomitant cationic/radical photopolymerization for the formation of an interpenetrating polymer network upon visible-light light-emitting diode(LED) exposure. The light absorption abilities of fluorescent brighteners were characterized by UV-visible spectrometer, the photochemical properties of them were analyzed by fluorescence spectrometer and electron spin resonance, the photoinitiation efficiencies of the photoinitiating systems were monitored by real-time Fourier transform infrared spectroscopy, meanwhile, the fracture surface morphology and surface morphology of the products obtained from the concomitant cationic/radical photopolymerization of epoxides/acrylates blends were observed and analyzed by scanning electron microscope and atomic force microscope, respectively. The results showed that fluorescent brighteners could be used as a versatile high-performance photoinitiator under visible-light LED, among them, the two-component and three-component photoinitiating systems based on naphthalene-benzoxazole OB 7, sulfonated triazinylstilbenes CBUS 450, sulfonated stilbene-biphenyl CBS X and coumarin C 1 exhibited quite excellent photoinitiating abilities even under air.



Material Chemistry

Synthesis and Lithium-storage Characteristics of Three-dimensional Cross-linked Graphene Nanofibers ^†

JI Tianyi, LIU Xiaoxu, ZHAO Jiupeng, LI Yao

2020, 41(4):  821-828.  doi:10.7503/cjcu20190581

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High crystalline 3D cross-linked graphene nanofibers(3DCGNs) were self-assembled from graphene oxide at high temperature. SEM and TEM tests show that the 3DCGNs have solid-core structure with a diameter less than 100 nm. The layers of graphene are arranged in order, with higher crystallinity. The material served as a negative electrode for lithium ion battery and exhibited excellent electrochemical properties, such as high first Coulombic efficiency(72.4%) and storage lithium capacity(692.7 mA·h/g at 0.1C), good rating performance(373.3 mA·h/g at 20C) and outstanding cycling stability(capacity retention of 84.1% after 1000 cycles) and so on. This research also adds new ideas for the preparation of graphene-based electrode materials.



Preparative Chemistry of N-containing Porous Carbon Nanofibers for Capacity Improvement in Lithium-sulfur Battery ^†

WANG Xia, LIU Yanji, JIA Yongfeng, JI Lei, HU Quanli, DUAN Limei, LIU Jinghai

2020, 41(4):  829-837.  doi:10.7503/cjcu20190549

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Mesoporous nitrogen-containing carbon nanofibers(MT-C) were prepared via carbonization of polyacrylonitrile(PAN) nanofibers at 1000 ℃ in a nitrogen atmosphere with polyvinylpyrrolidone(PVP) acting as pore-making agent. Under condition of m(PVP)/m(PAN)=2∶1, MT-C-0.4 with the largest specific surface area of 190.8 m ²/g exhibits the initial discharge specific capacity of 1269.4 mA·h/g at 0.05C. After 300 cycles at 0.5C, the specific capacity maintains at 658.3 mA·h/g with a capacity decay rate of 0.14% per cycle. In addition, when the sulfur areal loading amount is 1 mg/cm ², the MT-C-0.4/S presents the best electrochemical performances.



Preparation and Mechanical Properties of Carbon Fiber Triaxial Woven Fabric/Epoxy Composites ^†

SHA Di, YU Xumin, ZHAO Jiang, MA Xiaofei, WANG Hanfu, LIU Fangfang, QIU Xuepeng

2020, 41(4):  838-845.  doi:10.7503/cjcu20190513

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The triaxial woven fabric exhibits better mechanical properties than the ordinary fabrics due to its high symmetric weaving structure and good isotropy which can distribute the stress more effectively. In this study, the carbon fiber triaxial woven fabric/epoxy composites with different center distance dimensions between two warp(weft) yarns were prepared by hot press forming technology. The influences of center distance dimensions between two warp(weft) yarns and cutting angles of the specimens on the mechanical properties were studied and demonstrated by comparing with carbon fiber biaxial fabric/epoxy composites. The results show that the fracture strength at 0° decreases from 221.7 to 148.1 MPa and the tearing strength decreases from 1000 to 600 N with the yarn spacing increasing from 2 to 6 mm. Meanwhile, the fracture strength at 90° decreases from 50.0 to 22.1 MPa, the tearing strength decreases from 330 to 100 N and the bursting strength decreases from 424 to 216 N. These reductions in mechanical properties are ascribed to the decrease in the carbon fiber content per area and an increase in the pores of the fabric. The fracture strength of carbon fiber triaxial woven fabric/epoxy composite with a yarn spacing of 2 mm at 0°(based on weft), 30°, 45°, 60° and 90° is 221.7, 48.5, 44.3, 227.7 and 50.0 MPa, respectively. Obviously, the fracture strength at 0° and 60° are much higher than those at 30°, 45°, and 90°. According to the weaving principle of the triaxial woven fabric, the specimens at 0° and 60° are completely identical, so the fracture strength at these two angles is similar. Moreover, specimens at 0° and 60° have a set of yarns parallel to the applied load, which can restrain the deformation damage to a certain extent. However, the three sets of yarns at 30°, 45° and 90° all have a certain angle with the applied load, so the ability to distribute the applied load is weakened. By comparing with the carbon fiber biaxial fabric/epoxy composite, it is found that the comprehensive performances(fracture strength, tearing strength and bursting strength) of carbon fiber triaxial woven fabric/epoxy composite are significantly better. The fracture strength, tearing strength, and bursting strength of the carbon fiber triaxial woven fabric/epoxy composite can reach up to 221.7 MPa, 1000 N, and 424 N, respectively. This study has highlighted the advantages of triaxial woven fabric and laid the foundation for the subsequent preparation of various types of carbon fiber triaxial woven fabric composites and their wide application.



Preparation of Superhydrophobic Polyaniline/Polytetrafluoroethylenethylene Composite Membrane and Its Separation Ability for Oil-Water Emulsion ^†

REN Wen, ZHANG Guoli, YAN Han, HU Xinghua, LI Kun, WANG Jingfeng, LI Ruiqi

2020, 41(4):  846-854.  doi:10.7503/cjcu20190537

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With aniline as a raw material, polyaniline(PANI) composite membrane was synthesized on polytetrafluoroethylene(PTFE) by in-situ polymerization. The morphology, chemical structure and the wettability of PANI/PTFE composite membrane were analyzed by optical microscopy, scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), ultraviolet-visable absorption spectroscopy(UV-Vis) and static water contact angle tester, and the water separation performance, flux and cycle performance of the water-in-oil emulsion were tested. The results show that PANI/PTFE composite membrane can effectively separate oil-in-water emulsion only under gravity conditions, and it still has good anti-fouling ability and separation performance after filtration for dozens of times.