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Unraveling the Heterogeneity of Epoxy-amine Networks by Introducing Dynamic Covalent bonds

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Chinese Journal of Polymer Science 2023年第6期41卷 926-932,I0009页

作者： Hu Xu Yao Zhang Hao Wang Jin-Rong Wu State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu 610065China

Epoxy resins are a kind of universal thermosetting plastics,which are widely used as structural materials in various ***,it is necessary to understand the network structure of epoxy ***,it is challenging to reveal the network heterogeneity of epoxy resins due to the permanent covalent ***,we provide a novel strategy to characterize the network heterogeneity of epoxy resins by using the dynamic covalent bonds to replace the conventional covalent *** dynamic covalent bonds can reorganize under heat stimulus and the network keeps a constant crosslinking density during topological rearrangement,making it convenience to study the heterogeneity of epoxy ***-Williams-Watts(KWW)stretched exponential function is used to fit the stress relaxation data,and the parametersβandσperm/σ0 extracted from KWW equation indicate the network becomes more homogenous with the stoichiometric ratio of epoxy groups and amines decreases from 1/1 to 1/*** method proves that the side reaction between epoxy and hydroxyl is the main origin of the structural heterogeneity in epoxy resins compared to the secondary amines network.

关键词： resins bonds amines

Reconstruction of broken Si–O–Si bonds in iron ore tailings (IOTs) in concrete

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International Journal of Minerals,Metallurgy and Materials 2019年第10期26卷 1329-1336页

作者： Juan-hong Liu Yu-cheng Zhou Ai-xiang Wu Hong-jiang Wang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Urban Underground Space Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of High-efficient Mining and Safety of Metal Mines Ministry of EducationUniversity of Science and Technology BeijingBeijing 100083China

This paper reports a study on the reconstruction of broken Si O Si bonds in iron ore tailings (IOTs) in concrete. Limestone and IOTs were used to investigate the influence of different types of coarse aggregates on the compressive strengths of concrete samples. The dif- ferences in interfacial transition zones (ITZs) between aggregate and paste were analyzed by scanning electron microscopy (SEM) and ener- gy-dispersive spectroscopy (EDS). Meanwhile, X-ray diffraction (XRD) and infrared spectroscopy (IR) were used to study microscopic changes in limestone and IOTs powders in a simple alkaline environment that simulated cement. The results show that the compressive strengths of IOTs concrete or paste are higher than those of limestone concrete or paste under identical conditions. The Ca/Si atom ratios in the ITZs of IOTs con- crete samples are lower than those of limestone concrete;the diffraction peak of the calcium silicate phase at 2θ = 29.5°, as well as the bands of Si O bonds shifting to lower wavenumbers, indicates reconstruction of the broken Si-O-Si bonds on the surfaces of IOTs with Ca(OH)2.

关键词： iron ore tailings broken Si O Si bonds alkaline environment reconstruction

Enhancing ferromagnetic coupling in CrXY(X=O,S,Se;Y=Cl,Br,I)monolayers by turning the covalent character of Cr-X bonds

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npj Computational Materials 2023年第1期9卷 1781-1786页

作者： Hao-Ran Zhu Bin Shao Xu Zuo College of Electronic Information and Optical Engineering Nankai UniversityTianjinChina Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Nankai UniversityTianjinChina Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Nankai UniversityTianjinChina Engineering Research Center of Thin Film Optoelectronics Technology Ministry of EducationNankai UniversityTianjinChina

On the basis of first-principles calculations,we investigate the electronic and magnetic properties of 1T phase chromium sulfide halide CrXY(X=O,S,Se;Y=Cl,Br,I)monolayers in CrCl_(2) structure with the P3m1 space *** for the CrOI monolayer,all CrXY monolayers are stable and ferromagnetic *** results show that the ferromagnetic coupling is dominated by the kinetic exchange between the empty e_(g)-orbital of Cr atoms and the p-orbital of anions under the three-fold rotational *** this context,the coupling strength allows for being greatly enhanced by turning the nature of Cr–X bonds,i.e.,increasing the covalent contribution of the bonds by minimizing the energy difference of the coupled *** we illustrate for the example of CrOY,the Curie temperature(T_(c))is nearly tripled by substituting O by S/Se ion,eventually reaching the highest Tc in CrSeI monolayer(334 K).The high stabilities and Curie temperature manifest these monolayer ferromagnetic materials feasible for synthesis and applicable to 2D spintronic devices.

关键词： ferromagnetic bonds coupling

Diffusive-stochastic-viscoelastic model on specific adhesion of viscoelastic solids via molecular bonds

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Acta Mechanica Sinica 2019年第2期35卷 343-354页

作者： Kuncheng He Long Li Jizeng Wang Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

A diffusive-stochastic-viscoelastic model is proposed for the specific adhesion of viscoelastic solids via stochastically formed molecular bonds. In this model, we assumed that molecular level behaviours, including the diffusion of mobile adhesion molecules and stochastic reaction between adhesion molecules and binding sites, obey the Markovian stochastic processes, while mesoscopic deformations of the viscoelastic media are governed by continuum mechanics. Through Monte Carlo simulations of this model, we systematically investigated how the competition between time scales of molecular diffusion, reaction, and deformation creep of the solids may influence the lifetime and dynamic strength of the adhesion. We revealed that there exists an optimal characteristic time of molecule diffusion corresponding to the longest lifetime and largest adhesion strength, which is in good agreement with experimental observed characteristic time scales of molecular diffusion in cell membranes. In addition, we identified that the media viscosity can significantly increase the lifetime and dynamic strength, since the deformation creep and stress relaxation can effectively reduce the concentration of interfacial stress and increases the rebinding probability of molecular bonds.

关键词： Specific adhesion Molecular bonds Diffusion Monte Carlo simulation Continuum mechanics

Conductive,Stretchable,and Self-healing Ionic Gel Based on Dynamic Covalent bonds and Electrostatic Interaction

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Chinese Journal of Polymer Science 2019年第11期37卷 1053-1059页

作者： Yi Sun Yong-Yuan Ren Qi Li Rong-Wei Shi Yin Hu Jiang-Na Guo Zhe Sun Feng Yan Department of Polymer Science and Engineering College of Chemistry Chemical Engineering and Materials Science Soochow University

Integrating multiple functions into one gel that can be widely applied to electronic devices as well as chemical and biomedical engineering remains a big ***,a multifunctional ionic liquid/dynamic covalent bonds (ionic/DCB) type gel was designed and synthesized via one-pot *** the assistance of electrostatic interaction provided by the imidazolium cations of IL and the reversible DCB of boronic ester,as-prepared ionic/DCB gel showed good stretchable properties and high ionic conductivity at ambient *** addition,the electrostatic interaction between imidazolium cations and sulfonate anions and the reversible DCB led to enhanced chain mobility and thereby excellent self-healing ***,sulfonate anions in ionic/DCB gel could alleviate the migration of electronegative polysulfide and promote the transportation of electropositive lithium ion in lithium-sulfur battery ***,this work provides a new insight to promote the current research on self-healing gels,hopefully expanding their applications in electronic devices.

关键词： Ionic gel Conductivity Self-healing Dynamic covalent bonds Lithium-sulfur battery

Helium Plasma Damage of Low-k Carbon Doped Silica Film:the Effect of Si Dangling bonds on the Dielectric Constant

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Plasma Science and Technology 2014年第11期16卷 1050-1053页

作者：李海玲王庆巴德纯 School of Mechanical Engineering & Automation Northeastern University School of Mechanical and Vehicle Shenyang Institute of Technology

The low-k carbon doped silica film has been modified by radio frequency helium plasma at 5 Pa pressure and 80 W power with subsequent XPS, FTIR and optical emission spec- troscopy analysis. XPS data indicate that helium ions have broken Si-C bonds, leading to Si-C scission with C（1s） lost seriously. The Si（2p）, O（ls）, peak obviously shifted to higher binding en- ergies, indicating an increasingly oxidized Si（2p）. FTIR data also show that the silanol formation increased with longer exposure time up to a week. Contrarily, the CHa stretch, Si-C stretching bond and the ratio of the Si-O-Si cage and Si-O-Si network peak sharply decreased upon exposure to helium plasma. The OES result indicates that monovalent helium ions in plasma play a key role in damaging carbon doped silica film. So it can be concluded that the monovalent helium ions besides VUV photons can break the weak Si-C bonds to create Si dangling bonds and free methyl radicals, and the latter easily reacts with O_2 from the atmosphere to generate CO_2 and H_2O. The bonds change is due to the Si dangling bonds combining with H_2O, thereby, increasing the dielectric constant k value.

关键词： carbon doped silica film helium plasma bonds damage dielectric constant

Radical cascade reactions of unsaturated C–C bonds involving migration

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Science China Chemistry 2019年第11期62卷 1476-1491页

作者： Ge Zhang Yang Liu Jinbo Zhao Yan Li Qian Zhang Jilin Province Key Laboratory of Organic Functional Molecular Design&Synthesis Department of ChemistryNortheast Normal UniversityJilin 130024China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

During the past few years, with the rapid development of mild methods for the generation of radical species, great progress in radical cascade reactions of unsaturated C–C bonds has been made. Many radical cascade reactions involve functional groups migration, which leads structurally much more diverse, complex and valuable compounds not easily obtained through other methods. In this review, the recent achievements in unsaturated C–C bonds radical cascade reactions involving migration are summarized.

关键词： radical cascade reaction functional group migration unsaturated C–C bonds C-centered radicals N-centered radicals

B-C-N Compounds with Mixed Hybridization of sp^(2)-Like and sp^(3)-Like bonds

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Chinese Physics Letters 2012年第3期29卷 161-164页

作者： LUO Xiao-Guang HE Ju-Long Department of Electronics College of Information Technical ScienceNankai UniversityTianjin 300071 State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004

We perform first-principles calculations of the structural and electronic properties of hypothetical bc6-BC_(4)N and N-substituted bc6-BC4N,which are derived from a body-center-cubic carbon *** calculations show that the former is a semiconductor with an indirect band gap of 0.91 eV and the latter is *** calculated bond length,bond population,and charge density of N-substituted bc6-BC4N indicate that one C-N bond has been broken after N-substitution,which means that the structure contains a mixed hybridization of sp^(2)-like and sp^(3)-1ike *** the pressure above 100 GPa,the structure changes to a pure sp^(3)-like hybridization.

关键词： structure substituted bonds

A new method for quick predicting the strength of intermolecular hydrogen bonds

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Science China Chemistry 2009年第2期52卷 153-160页

作者： SUN ChangLiang ZHANG Yan JIANG XiaoNan WANG ChangSheng YANG ZhongZhi Department of Chemistry Liaoning Normal UniversityDalian 116029China

A new method is proposed to quick predict the strength of intermolecular hydrogen *** method is employed to produce the hydrogen-bonding potential energy curves of twenty-nine hydro-gen-bonded *** calculation results show that the hydrogen-bonding potential energy curves obtained from this method are in good agreement with those obtained from MP2/6-31+G calculations by including the BSSE correction,which demonstrate that the method proposed in this work can be used to calculate the hydrogen-bonding interactions in peptides.

关键词： intermolecular hydrogen bonds hydrogen-bonded dimer hydrogen-bonding potential energy curves