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10 June 2024, Volume 45 Issue 6

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Cover and Content of Chemical Journal of Chinese Universities Vol.45 No.6(2024)

2024, 45(6):  1-5. 

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Review

Research Progress on the Molecular Structure of Amorphous Chalcogen Elements

SHI Wuyi, BAO Yu, CUI Shuxun

2024, 45(6):  20240054.  doi:10.7503/cjcu20240054

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Chalcogen elements（including sulfur， selenium， and tellurium） are essential substances in the nature and have wide-range applications in photoelectric materials， batteries， semiconductors， and other fields. Chalcogen elements have two structural forms： crystalline and amorphous. While the molecular structure of crystalline chalcogen elements has been extensively investigated， the molecular structures of amorphous chalcogen elements remain uncertain. To better explore the potential applications of amorphous chalcogen elements， it is necessary to study their structure and properties. This paper summarizes recent advancements in understanding the molecular structure of amorphous chalcogen elements and envisages potential research directions. These efforts aim to contribute to a more comprehensive understanding of the properties of amorphous chalcogen elements and to foster their application across diverse fields.



Article: Inorganic Chemistry

Mechanism of Solid Solution Softening Behavior in Four Binary Alloys Fe-X（X=Cr， Co， Mo， W） at Low Temperatures and Concentrations

WANG Na, LI Xiangfei

2024, 45(6):  20240119.  doi:10.7503/cjcu20240119

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In this study， the mechanism of the solid solution softening（SSS） behavior in four binary alloys of body-centered cubic（bcc） iron Fe-X（X=Cr， Co， Mo， W） at low temperatures and concentrations was investigated using first-principles calculations. The SSS behavior of bcc Fe at low temperatures and concentrations is controlled by the nucleation of double kinks. The intrinsic mechanism for SSS occurs when solute atoms directly reduce the nucleation energy barrier for the formation of double kinks. The extrinsic mechanism for SSS occurs when solute atoms reduce the number of interstice atoms， thereby reducing the nucleation energy barrier for double kinks. We calculated the atomic row displacement（ARD） energy and the generalized stacking fault（GSF） energy to clarify the SSS mechanism of the Fe-X（X=Cr， Co， Mo， W） binary alloys. The calculations showed that only Cr can slightly reduce the ARD and GSF energies， while Co， Mo， and W all cause an increase in the ARD and GSF energies. Therefore， according to the intrinsic mechanism of SSS， only Cr causes solid solution softening， while Co， Mo， and W all cause solid solution strengthening. Cr， Mo， and W interact with the surrounding Fe atoms in an antiferromagnetic manner， while Co interacts with Fe in a ferromagnetic manner. Although the ferromagnetic/antiferromagnetic interaction is somewhat correlated with the valence electron number and electron configuration， the nucleation energy barrier is not significantly correlated with them. Further calculations showed that there is a positive correlation between the nucleation energy barrier and the binding energy. The binding energy between Cr and Fe weakens， thus lowering the double kink nucleation energy barrier， while the binding energy between Co， Mo， W， and Fe strengthens， thus increasing the double kink nucleation energy barrier. However， the binding energy did not show a significant correlation with atomic radius or electron configuration， thus the nucleation energy barrier is not significantly correlated with these factors either. Considering the intrinsic mechanism， the increase in the binding energy between Co， Mo， W， and Fe causes the nucleation energy barrier for double kinks to increase， resulting in solid solution strengthening. Therefore， the SSS behavior of the Fe-based binary alloys with Co， Mo， and W at low temperature and low concentration cannot be explained by the intrinsic mechanism， and external mechanisms， such as the effects of interstitial C atoms， need to be considered. On the other hand， the solid solution softening behavior of Cr may be explained by the intrinsic mechanism.



Analytical Chemistry

Detection of Perfluorooctane Sulfonate in Aqueous Environment Based on Molecular Imprinting Coupled Bipolar Electrochemiluminescence Sensor

HUANG Shengxiu, LIU Liyang, YANG Weiqiang, WANG Qingxiang, NI Jiancong

2024, 45(6):  20240106.  doi:10.7503/cjcu20240106

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Combining the specific recognition ability of molecular imprinting polymer（MIP） and the high sensitivity and anti-interference characteristics of bipolar electrochemical luminescence sensing（BPECL）， an MIP/BPECL sensor was constructed for the detection of perfluorooctane sulfonate（PFOS） in sewage. Using PFOS as the template molecule and o-phenylenediamine（o-PD） as the functional monomer， the molecular-imprinted polymer was specifically identified by negative extreme electropolymerization of bipolar electrodes. The electrodes were characterized by means of scanning electron microscopy（SEM） and cyclic voltammetry（CV）. The MIP/BPECL sensing system was constructed with ruthenium bipyridine/tri-n-propylamine［Ru（bpy）₃²⁺/TPrA］ as the output signal at the positive extremity of the bipolar electrode. Under optimized conditions， the electrochemical sensor displayed a wide linear range from 1 nmol/L to 1000 nmol/L with a low limit of detection of 0.43 nmol/L（S/N=3）. The sensor is applied to the actual sample of the environmental water labeling recovery test， and the result is good. The constructed MIP/BPECL sensor has the advantages of high sensitivity， good specificity and strong anti-interference ability. By changing the template molecule of molecular imprinting， it is expected to realize the application of this sensor in the detection of other environmental pollutants.



Assembly of Functionalized MIL-101（Cr）-loaded Quartz Crystal Microbalance Gas Sensors for Formic Acid Detection

CHEN Yating, WANG Peng, GUO Baoying, FU Siyun, LIU Wanning, CHEN Shuyi, SHI Yu, CAI Songliang, ZHENG Shengrun, FAN Jun, ZHANG Weiguang

2024, 45(6):  20240031.  doi:10.7503/cjcu20240031

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Volatile organic compounds（VOCs） are considered as one of the major components in atmospheric pollutants， and pose serious hazards to both human health and the environment. It is urgent to develop new high- efficient detection techniques for VOCs. In this work， ethylenediamine（ED） and ethanolamine（EA） were grafted into MIL-101（Cr） to obtain ED- and EA-derived MIL-101（Cr） materials［labeled as MIL-101（Cr）-ED and MIL-101（Cr）-EA］， respectively. Then， these three MIL-101（Cr） materials were loaded on the surface of quartz crystal through dip coating to assemble three kinds of MIL-101（Cr）-modified quartz crystal microbalance（QCM） gas sensors， respectively. Moreover， the sensing and recognition performance of these QCM sensors toward methanol， ethanol， 2-propanol， acetone， cyclohexane， diethylamine， formic acid， formaldehyde， ammonia， and acetic acid were studied in detail. As indicated， MIL-101（Cr）-ED- and MIL-101（Cr）-EA-loaded QCM sensors showed better sensing performance for formic acid in comparison with the original MIL-101（Cr）-based sensor， and the oscillation frequency of these two sensors decreased by -375.6 and -232.1 Hz when the concentration of formic acid was 350 mg/L， respectively. Δf value was linearly related to the concentration of formic acid in the range of 5—350 mg/L. In addition， the sensitivity of MIL-101（Cr）-ED-loaded QCM gas sensor was estimated to be 0.95 Hz·L·mg^-1 and the limit of detection was 0.95 mg/L. As a result， this MIL-101（Cr）-modified QCM gas sensor demonstrated high sensitivity， low detection limit， and good repeatability. In brief， this research would provide some useful information for developing new QCM gas sensors in real-time VOCs detection.



Room Temperature Driven Sodium Humate-protected Carbon Nanoclusters for Fluorescent and Colorimetric Sensing of Ag⁺ and Temperature

LI Lin, MA Jing, XU Changlin, CHEN Tongyao, GUO Hengyao, LI Ziyou, WU Wenxin

2024, 45(6):  20230510.  doi:10.7503/cjcu20230510

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Based on hydrogen bonding self-assembly strategy， hypotoxicity and water-soluble cyan fluorescent carbon nanoclusters（HAN-CNCs） were constructed to employ a highly-efficient green economy and room temperature synthesis method， which used ascorbic acid and high biocompatibility coal-based sodium humate with abundant hydroxy as raw materials. The as-prepared HAN-CNCs can be specifically quenched by Ag⁺ at pH of 5.0， with a wide detection range （5.0—300 μmol/L） and a low detection limit of 27.5 nmol/L. It was found that Ag⁺ can induce fluorescence static quenching of the HAN-CNCs， owing to the coordination interaction between Ag⁺ and amine groups or carbonyl groups on the surface of HAN-CNCs. More interestingly， the colorimetric detection of Ag⁺ could be additionally realized by visible color conversion （yellowish-rubricans） under the daylight lamp and the cyan fluorescence gradually changed to blue purple under the irradiation of an ultraviolet lamp. From this， the HAN-CNCs were employed in the fabrication portable test strip for colorimetry monitoring of Ag⁺via the green-blue（G/B） analysis. In addition， HAN-CNCs exhibit an excellent reversible thermal response in the range of 20—85 ℃ and have potential as a temperature sensor. Furthermore， the HAN-CNCs exhibited a low biotoxicity and an excellent cell permeability when selectively detecting Ag⁺ in living cells by fluorescence microscopy imaging， indicating that the sensing system can be effectively applied to assessing potential risks and health security.



Organic Chemistry

An Electrically Responsive Multiple Chiroptical Switching System Based on a Rhodol Derivative

WANG Tongtong, WANG Tiefeng, XU Fei, YU Yang

2024, 45(6):  20240118.  doi:10.7503/cjcu20240118

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In this study， a chiral aniline structure was introduced into the 3′-amino-6′-hydroxyspiro［2-benzofuran-3，9′-xanthene］-1-one（Rhodol） derivative main molecule， which exhibits pH（acid and base）-responsive color changes. Then， based on the proton-coupled electron transfer mechanism， a novel electrically responsive multiple chiroptical switching system was constructed by integrating the functional Rhodol derivative with electro-acid/base molecules. Controlled by suitable voltages， this system could switch among three circular dichroism absorption states reversibly： in the visible light range， no circular dichroism signal at the initial state， positive circular dichroism signal under a significant positive voltage， and negative circular dichroism signal under a considerable negative voltage. More importantly， all the switching processes were totally reversible. This research opens a new route to achieve the development of electrically responsive multiple chiroptical switching systems， and offers an important insight on the design and application of innovative materials for multiple chiroptical switches.



Methodologies for the Precise Modification of Guest Molecules by Proteins

DAI Zhen, LIU Yu, LIU Tao

2024, 45(6):  20240090.  doi:10.7503/cjcu20240090

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Precise modification of guest molecules on proteins is a crucial technological foundation for supramole- cular modulation of protein activity. This is especially true for aromatic functional group guests containing positive charges， which can be efficiently bound to cucurbituril. However， precise modification of these molecules on proteins using non-canonical amino acid site specific modification technology can be challenging. The linkers of bioorthogonal reactions are often large， which can affect the recognition of the host and guest molecules. To address this issue， the target proteins were modified by adding iodine- or alkynyl-functional amino acids using the non-canonical amino acid site specific modification technology. The pyridine molecules with a positive charge were efficiently bound to cucurbituril molecules using the palladium-catalyzed Suzuki and Sonogashira coupling reaction. Subsequently， a non-natural amino acid with an alkynyl functional group was successfully incorporated into the target proteins using a series of reaction conditions. Furthermore， a Sonogashira coupling reaction was utilized to attach a positively charged pyridine molecule to the protein surface. These accomplishments establish a crucial technological basis for the chemical regulation of proteins through host-guest interactions.



Physical Chemistry

Three-dimensional Porous Cu with Bi Modified Layer to Synergistically Construct Dendrite-free Li Metal Electrode

WANG Shuai, SUN Yuhan, GAO Xin, SONG Rui, ZHAO Mingqin, LU Yao, BAO Xiaobing, LUO Qiaomei, GOU Lei, FAN Xiaoyong

2024, 45(6):  20240122.  doi:10.7503/cjcu20240122

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In this paper， three-dimesional（3D） Cu@Bi was constructed by electrodepositing a bismuth modification layer on the surface of 3D porous copper with micrometer-sized pores prepared by an electroless plating， and served as the current collector to improve the electrochemical performance of Li metal electrode. The 3D porous structure with a pore diameter of about 5 μm has a high surface area， which reduces the local current density and results in uniform current density distribution， and its large free space can alleviate the volume change， release the stress and inhibit the growth of lithium dendrites. In addition， under the assistance of high lithophilicity of Bi modified layer， the 3D Cu@Bi decreases the nucleation overpotential of Li， and enhances the reversibility of lithium plating/stripping. Under the synergistic effects of 3D porous structure and Bi modified layer， the electrode surface remains flat and smooth even when the lithium metal deposition capacity is more than 4 mA·h/cm². The half cells assembled by it can be stably cycled for more than 200 cycles and the Coulomb efficiency（CE） can be maintained above 98.5%. The symmetrical cell Li||3D Cu@Bi@Li stably circles for above 1500 h at high current density of 0.5 mA/cm² with a capacity of 1 mA·h/cm²， and the electrode surface is still smooth and free of dendrites after 100 cycles. The full cell LFP||3D Cu@Bi@Li with LiFePO₄（LFP） as the cathode shows a high capacity of 132 mA·h/g and a capacity retention rate of ca. 87.2% after 200 cycles at a rate of 1C.



Catalysis and Simulation of SBA-15 Zeolite Supported p-Toluenesulfonic Acid for the Synthesis of Dicumyl Peroxide

ZHANG Xiaolong, ZHANG Yicheng, LI Qingchao, ZHA Fei, CHANG Yue, TANG Xiaohua

2024, 45(6):  20240067.  doi:10.7503/cjcu20240067

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SBA-15 zeolite suppored p-toluenesulfonic acid（TsOH/SBA-15） was prepared using the impregnation method. The catalytic activity of TsOH/SBA-15 in synthesis of dicumyl peroxide（DCP） from α-methylstyrene（α-MS） reacted with isopropylbenzene hydroperoxide（CHP） was evaluated. Under the conditions of m（TsOH/SBA-15）/ m（CHP）=0.15%， n（α-MS）/n（CHP）=2.0， 44 ℃ and 2.5 h， the yield of DCP was 62.1%. Simulation analysis suggested that the reaction process follows two mechanisms of asynchronous synergistic reaction and step-by-step reaction. α-MS， CHP， and TsOH undergo a single transition state in the asynchronous synergistic reaction process， while there are two transition states and one intermediate in the step-by-step reaction， both requiring H⁺ proton transformation. The reaction energy barrier in the asynchronous synergistic reaction was calculated to be 121.8 kJ/mol at 44 ℃， while the reaction energy barriers were 74.1 and 78.3 kJ/mol in the two transition states in the step-by-step reaction， respectively.



Theoretical Research of Two-dimensional Semiconductor R57-BN as Anode Material of Sodium-ion Battery

WANG Wenchun, MA Tianci, LIU Chunsheng

2024, 45(6):  20240043.  doi:10.7503/cjcu20240043

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As promising alternatives to lithium-ion batteries（LIBs）， sodium-ion batteries（SIBs） have garnered significant interest owing to the abundant resources， low cost， and similar storage mechanism with LIBs. However， the lack of suitable anode materials is a major bottleneck of SIBs. Two-dimensional（2D） materials are promising anode materials for batteries due to their large surface area and short diffusion paths. In this paper， a pentagonal and heptagonal 2D semiconductor structure R57-BN composed of B and N atom was predicted， and the electrochemical properties of R57-BN as anode material of SIBs were studied based on first-principles calculations. 2D R57-BN shows great stability in dynamic and thermodynamic aspects. The computation results reveal that Na atom can be adsorbed on R57-BN without clustering， and the adsorbed energy of Na-ion on the R57-BN is 1.55 eV. Even at low intercalated Na concentration， the Na adsorbed R57-BN system demonstrates metallic characteristics， showing good electronic conductivity. The diffusion barrier of Na diffusion on the surface of R57-BN is as low as 0.55 eV. Meanwhile， R57-BN has high specific capacity（662.40 mA·h/g） and suitable average open circuit voltage（V_OC， 0.50 V）. Based on the above results， R57-BN can serve as a potential anode material for SIBs. The present research can provide a good theoretical basis and thus conduce to guiding the developing of good Na storage materials， and also supply strong background for experimental researches.



Preparation of Porous Carbon Nanofiber Loaded Copper-platinum Alloy Catalysts and Their Electrocatalytic Hydrogen Evolution Performance

CHEN Xin, LIU Jingyuan, YU Jing

2024, 45(6):  20240042.  doi:10.7503/cjcu20240042

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In this investigation， a series of PtCu nano-alloy catalysts with varying alloy ratios were prepared on porous carbon nanofibers（PCNFs） using electrostatic spinning and staged heat treatment methods. The effect of the geometrical morphology of the alloy particles and the Cu-Pt-Cu structure on the hydrogen evolution efficiency was discovered. The study determined that the most effective hydrogen evolution performance was achieved using a PtCu additive molar ratio of 1∶2 under acidic conditions， resulting in an overpotential of 37 mV at 10 mA/cm² and exhibiting robust long-term stability. This research presents an innovative approach for producing binary alloy nanocatalysts of PCNFs impregnated with transition metals and Pt.



Size Effect on “Hot Spot” of Au Nanoparticle Dimer-Au Plate Coupling System

ZENG Ziqiang, ZHANG Chenjie, XU Minmin, YAO Jianlin

2024, 45(6):  20240022.  doi:10.7503/cjcu20240022

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The "hot spot" effect has attracted considerable attention in surface enhanced spectroscopy and relevant fields， especially for the controllable fabrication of the dynamic "hot spot" by using the size and excitation wavelength dependent transfer effect. Herein， the coupling system of spherical dimer of gold nanoparticles and gold plate is theoretically simulated by finite element method（FEM）， and the effects of excitation wavelengths and nanoparticle sizes on the electromagnetic field enhancement at different gaps of the system are systematically investigated. The results demonstrated that the two modes of surface plasmon resonance were observed. As the size of nanoparticle is 30 nm and the excitation wavelength is 450—535 nm and 670—950 nm， the two plasmon resonance modes were mainly dominated by a cooperative effect， and “hot spot” mainly located in the particle-particle gap. As the size of nanoparticles was increased to 85 nm or even 105 nm， a competition effect between the two plasmon resonance modes was occurred for the excitation wavelengths of 670—695 nm and 725—755 nm. It resulted in the transformation of “hot spot” from particle-particle gap to particles-gold plate gap successfully. It was anticipated that the theoretical simulation provided an alternative approach for control and transfer on the “hot spot” and it was beneficial to design and fabricate the substrate with high performance of surface enhanced optical effect.



Interaction Between Hot Water Chemical Drive System and Thick Oil Components and Theoretical Simulation Research

HAN Yugui, LIU Changlong, ZHAO Peng, ZHENG Wenwen, LIU Yuepeng, LI Yi

2024, 45(6):  20230456.  doi:10.7503/cjcu20230456

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To investigate the effects of temperature and polymer chemistry on the properties of thick oil， the thick oil fractions were analyzed by scanning electron microscopy， Fourier transform infrared spectrometer and rheometer. scanning electron microscopy. Results indicated that the asphaltene surface morphology was irregular， and the colloid surface was rough and had a pore structure. Fourier infrared spectroscopy detected three thick oil fractions with characteristic absorption peaks of aromatic hydrocarbons. Rheological performance test was conducted to investigate the effects of polymer chemical addition， mineralization， temperature and pH on the rheological performance and interfacial film properties of thick oil. The experimental results showed that the polymer dosage had a significant effect on the energy storage modulus and loss modulus of the thick oil， while the increase of mineralization enhanced the complex viscosity of the thick oil， and the viscoelasticity of the thick oil was stronger under acidic and alkaline conditions than that under neutral conditions. It was found through theoretical studies that the addition of polymer chemistries reduced the viscosity of thick oil and the effect was more pronounced at higher temperatures. The interaction between bitumen and polymer chemicals was the strongest， followed by colloid and the weakest interaction with oil components. The polymer chemical had no significant effect on the radial distribution function of the thick oil components， and mainly affected the thick oil components at the interface. Polymer chemicals and bitumen could form hydrogen bonds， and the addition of polymer chemicals decreased the number of hydrogen bonds within the bitumen and increased the number of hydrogen bonds with the polymer chemicals. The increase of temperature decreased the number of hydrogen bonds， especially between the asphaltene and the polymer chemical.



Polymer Chemistry

Influence of Processing Techniques on Carbon Black Dispersion and Mechanical Performance of Polyisoprene-based Rubbers

FENG Xueyang, WANG Yuge, HE Tiancheng, WANG Ke, PAN Lijia, CHEN Siyuan, YIN Yuan, SUN Hongguo, ZHENG Yafang, WEI Lai, SUN Zhaoyan

2024, 45(6):  20240045.  doi:10.7503/cjcu20240045

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The main components of natural rubber， polyisoprene rubber， and bionic rubber are all cis-1，4-polyisoprene， but there are certain differences in components such as proteins and phospholipids. These differences in composition may lead to different responses of rubber to compounding processes， resulting in variations in the dispersion of fillers in rubber and subsequently affecting the dynamic and static properties of vulcanized rubber. In order to investigate the variation patterns of filler dispersion and rubber mechanical properties of polyisoprene rubbers under different mixing processes， this study employed N220 carbon black as a filler and systematically investigated the carbon black dispersion and dynamic/static properties of natural rubber， polyisoprene rubber， and bionic rubber under four processing techniques. The results of the study show that the filler dispersion and mechanical properties of natural rubber and polyisoprene rubber exhibited a stronger response to the carbon black incorporating time， while bionic rubber showed a weaker response. With increasing carbon black incorporating time， the mean agglomerate size of natural rubber and polyisoprene rubber decreased from approximate 22 μm and approximate 19 μm to approximate 9 μm， resulting in a significant improvement in dynamic/static properties. In contrast， under the same processing conditions， the mean agglomerate size of bionic rubber decreased from approximate 20 μm to approximate 16 μm， and the carbon black dispersion state was poorer. On the other hand， bionic rubber showed a more sensitive response to plasticization time， and an extended plasticization time significantly reduced the mean agglomerate size of carbon black， enhancing its tensile fatigue performance. Accordingly， this study designed a process combining a longer plasticization time（6 min） with compounding， further enhancing the tensile fatigue performance of bionic rubber. To elucidate the reasons for the differential response of bionic rubber to compounding and plasticization processes， the study explored the variation patterns of Mooney viscosity and molecular weight of bionic rubber under different processing conditions. It was found that moderate molecular weight and a relatively narrow molecular weight distribution were conducive to improving the tensile fatigue performance of the rubber.



Broadband Dielectric Spectroscopy Study of Dynamics of Telechelic Polypropylene Glycol Melts

BAI Rong, LI Shangwei, CHEN Quan, SUN Zhaoyan, XU Wensheng

2024, 45(6):  20240013.  doi:10.7503/cjcu20240013

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Excellent polymer electrolytes require a combination of high ionic conductivity and mechanical strengths. An in-depth understanding of the relationship between polymers’ microscopic structure and dynamics and macrosco-pic conductive and mechanical properties is essential for the molecular design of high-performance polymer electrolytes. In the present paper， we selected low temperature of glass transition（T_g） and non-crystalline telechelic polypropylene glycol melts as a model system to investigate the molecular dynamics of associating polymers. Allyl-terminated polypropylene glycols having molecular weights of 1000， 2000 and 4000 were synthesized by chemically modifying the end groups， and the influence of chain-end interaction strength and molecular weight on their multi-scale dyna-mics was investigated using broadband dielectric spectroscopy. The polypropylene glycols with two different end groups exhibit both the α-relaxation associated with the segmental motion and the normal mode relaxation associated with the global motion of the chain. End group interactions influence both two relaxations； stronger interactions lead to longer relaxation time at the same temperature. This effect becomes more pronounced for the lower-molecular-weight samples， because the motion has been suppressed for the denser end groups therein. The generalized entropy theory was utilized to study the glass formation of telechelic polymer melts having variable sticky interaction strength and molecular mass， and theoretical predictions were shown to be in qualitative agreement with experimental results. These dynamic details can be used in guiding the molecular design of polymer electrolytes.



Preparation of Electro-nanofiltration Membranes with High Li⁺/Mg²⁺ Separation Performance via Sequential Interfacial Polymerization

LIU Huili, WANG Jing, CHEN Jiashuai, SONG Zhihao, JIANG Yumeng, GUO Zhiyuan, ZHANG Panpan, JI Zhiyong

2024, 45(6):  20230484.  doi:10.7503/cjcu20230484

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Highly selective electro-nanofiltration membranes（ENFMs） were prepared by regulating the aqueous-phase monomers of interfacial polymerization（IP） and constructing the positively charged surface by sequential interfacial polymerization（SIP） for the separation of lithium and magnesium by selective electrodialysis processes. The IP reaction was carried out using different aqueous-phase monomers with trimesoyl chloride to achieve the regulation of the pore size and charging property of the separation membranes. The optimum Li⁺/Mg²⁺ separation performance（4.75） of the membrane was achieved when piperazine was used as the aqueous-phase monomer. Subsequently， the SIP reaction was utilized to introduce positively charged aqueous-phase monomer polyethyleneimine（PEI， M_W=70000） of different concentrations on the optimal IP membrane surface， which converted the charge of the membrane surface from negative to positive. With the increase of PEI concentration， the positive charge density on the membrane surface increased significantly； the optimal SIP membrane achieved outstanding selectivity for Li⁺/Mg²⁺（15.90） and high Li⁺ flux（3.26×10^‒8 mol⋅cm^‒2⋅s^‒1）， which breaks the traditional “Trade-off” effect and lays the foundation for the subsequent research and application of Li⁺/Mg²⁺ separation salt-lake brines.