检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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

Interplay of Crosslinking Structures and Segmental Dynamics in Solid-Liquid Elastomers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2022年第10期40卷 1297-1306,I0012页

作者： Hao Wang Wan-Su Peng Qi wu Yan Zhao Shi-Tai Wang Yi Yang jin-rong wu Xiao-Liang Wang rong-Chun Zhang South China Advanced Institute for Soft Matter Science and Technology(AISMST) School of Emergent Soft MatterSouth China University of TechnologyGuangzhou 510640China Key Laboratory of High-Performance Polymer Materials and Technology of Ministry of Education Department of Polymer Science and EngineeringSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210093China State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu 610065China Suzhou Niumag Analytical Instrument Corporation Chengdu 610065China Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices South China University of TechnologyGuangzhou 510640China

There have been significant interests in recent years for incorporating dynamic bonds into polymer materials for achieving multiple functionalities,such as self-healing,recycling,stimuli-responsiveness,and so ***,the impact of dynamic bonds on the polymer dynamics is actually less *** this study,we investigate a self-healing solid-liquid elastomer(SLE),which is a dual-crosslinked network made by coupling a permanently crosslinked polydimethylsiloxane(PDMS)network with polyborosiloxane(PBS)via abundant dynamic boron/oxygen dative *** double-quantum(DQ)NMR reveals that the crosslinking degree is reduced while the structural heterogeneity of network is enhanced with increasing PBS content,i.e.,increasing the content of dynamic boron/oxygen dative *** experiments clearly reveal two chain relaxation modes in the SLE samples with a characteristic relaxation time of around 2.1 s and 11.8 s,corresponding to the relaxation of coupled PBS and PDMS chains,*** master curves obtained from variable-temperature frequency-dependent rheological experiments also reveal enhanced heterogeneity of chain relaxation with increasing PBS ***,the impact of boron/oxygen dative bonds on the Rouse dynamics is further revealed by fast-field-cycling(FFC)NMR experiments,where the spinlattice relaxation rate(R_(1))of all SLE samples follows the same power law of R_(1)(ω)∝ω^(-0.33).Nevertheless,the incorporation of PBS did slightly increase the energy barrier of Rouse *** study well demonstrates a combined use of rheology and solid-state NMR spectroscopy can provide piercing insights into the interplay of crosslinking structures and dynamics of polymer materials.

关键词： Fast-field-cycling NMR Multiple-quantum NMR Rheology Dynamics Dynamic bonds

Ultra-robust Metallosupramolecular Hydrogels with Unprecedented Self-recoverability using Asymmetrically Distributed Carboxyl-Fe3+Coordination Interactions

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第2期41卷 250-257页

作者： Zhao-Yang Yuan Zhen-Xing Cao Rui wu Hui Li Qiong-Jun Xu Hai-Tao wu jing Zheng jin-rong wu State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu610065China

Recently,numerous mechanically robust synthetic hydrogels have been ***,unlike natural loading-bearing materials such as cartilages and muscles,most hydrogels have inherently contradictory requirements,obstructing the design of hydrogels with characteristics of robustness and rapid ***,we present a facile strategy for constructing mechanically robust and rapidly self-recoverable *** linear poly(acrylamide-co-itaconic acid)chains crosslink via coordination bonds and minimal chemical crosslinkers to form the hydrogel *** design endows the coordination interactions to be asymmetrically *** deformation,the coordination interactions exhibit a reversible dissociation-and-reorganization property,demonstrating a new mechanism for energy dissipation and stress ***,the hydrogels possess tensile strength up to 12.5 MPa and toughness up to 28.2 MJ/***,the inherent dynamic nature of the coordination bonds imparts these hydrogels with stretch rate-and temperature-dependent mechanical behavior as well as excellent self-recovery *** method employed in this study is universal and is applicable to other polymers with load-bearing yet rapid recovery *** study will facilitate diverse applications of most metallosupramolecular hydrogels.

关键词： Metallosupramolecular hydrogels Coordination interactions Self-recoverability

A Triple Crosslinking Design toward Epoxy Vitrimers and Carbon Fiber Composites of High Performance and Multi-shape Memory

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2021年第6期39卷 736-744,I0007页

作者： Hao Wang Han-Chao Liu Yao Zhang Hu Xu Bi-Qiang jin Zhen-Xing Cao Hai-Tao wu Guang-Su Huang jin-rong wu State Key Laboratory of Polymer Materials Engineering Collegeof Polymer Science and EngineeringSichuan UniversityChengdu 610065China Changzhou Architectural Research Institute Group CO.LTD Changzhou 213001China

It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical ***,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer(MSMEV),which exhibits high mechanical properties,multi-shape memory property and *** triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F(DGEBF)with 4-aminophenyl disulfide,γ-aminopropyltriethoxysilane(APTS)and poly(propylene glycol)bis(2-aminopropyl ether)(D2000).The triple crosslinking manifests triple functions:the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network;the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region,leading to multi-shape memory property;a small amount of D2000 increases the modulus difference between the glassy and rubbery states,thereby improving the shape fixity ***,the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s ***,integrating carbon fibers and MSMEV results in shape memory *** superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.

关键词： Multi-shape memory Epoxy vitrimer High mechanical performance Triple crosslinking Composites

Flame-retardant and Self-healing Biomass Aerogels Based on Electrostatic Assembly

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第12期38卷 1294-1304页

作者： Ji-Yu Yang Yu Xia jin Zhao Long-Fei Yi Yong-Jiao Song Hong wu Shao-Yun Guo Li-Juan Zhao jin-rong wu College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610066China State Key Laboratory ofPolymer Materials Engineering Polymer Research InstituteSichuan UniversityChengdu 610065China State Key Laboratory ofPolymer Materials Engineering Collegeof Polymer Science and EngineeringSichuan UniversityChengdu 610065China

It remains a significant challenge to fabricate self-healing aerogels with excellent flame ***,we develop a class of biomass aerogels by electrostatically assembling chitosan(CS),phytic acid(PA),and itaconic acid(IA).The electrostatic interaction between CS and IA is weak and dynamic,so freeze-drying the solution of CS and IA enables the formation of continuous aerogel skeleton with self-healing ability and re-programmability;in comparison,the electrostatic interaction between CS and PA is strong and less dynamic,and thus mixing PA with CS in aqueous solution leads to fine precipitates of high flame retardancy due to the synergistic phosphorus-nitrogen *** the continuous skeleton and the fine precipitates results in self-healing aerogles with UL-4 V-0 rating of flame retardancy aerogels and autoextinguishable ***,the aerogels after burning in flame for 30 s form a skin-core structure,and the carbonized skin protects the integrity of the aerogels and the self-healing ability of the internal ***,this work provides a facile strategy to develop multifunctional aerogels which hold great promise for advanced applications.

关键词： Chitosan Flame retardancy Electrostatic interactions Biomass aerogel Self-healing

A Robust Self-healing Polyurethane Elastomer Enabled by Tuning the Molecular Mobility and Phase Morphology through Disulfide Bonds

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2021年第10期39卷 1299-1309,I0007页

作者： Hai-Tao wu Bi-Qiang jin Hao Wang Wen-Qiang wu Zhen-Xing Cao Zhao-Yang Yuan Yue Huang Wei-Hang Li Guang-Su Huang Lu-Sheng Liao jin-rong wu State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineerngSichuan UniversityChengdu 610065China Guangdong Provincial Key Laboratory of Natural Rubber Processing Agricultural Products Processing Research Institute of Chinese Academy of Tropical Agricultural SciencesZhanjiang 524001China

Elastomers with outstanding strength,toughness and healing efficiency are highly promising for many emerging ***,it is still a challenge to integrate all these beneficial features in one ***,an asymmetric alicyclic structure adjacent to aromatic disulfide was tactfully introduced into the backbone of polyurethane(PU)***,such elastomer(PU-HPS)was fabricated by polycondensing polytetramethylene ether glycol(PTMEG),isophorone diisocyanate(IPDI)and p-hydroxydiphenyl disulfide(HPS)via one-pot *** molecular mobility and phase morphology of PU-HPS can be tuned by adjusting the HPS ***,the dynamic exchange of hydrogen and disulfide bonds in the hard segment domains can also be *** optimized sample manifests outstanding tensile strength(46.4 MPa),high toughness(109.1 MJ/m^(3)),high self-healing efficiency after fracture(90.3%),complete scratch recovery(100%)and good puncture ***,this work provides a facile strategy for developing robust self-healing polymers.

关键词： Self-healing Polyurethane Disulfide bonds Chain mobility Phase morphology

Inhomogeneous Natural Network Promoting Strain-induced Crystallization:A Mesoscale Model of Natural Rubber

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第11期37卷 1142-1151页

作者： Han Liu Guang-Su Huang Lai-Yun Wei Jian Zeng Xuan Fu Cheng Huang jin-rong wu College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering Sichuan University

Although synthetic rubbers show continuously improved mechanical properties,natural rubber (NR) remains irreplaceable in the rubber family due to its superior mechanical properties.A mainstream viewpoint regarding the superiority of NR is that NR possesses a natural network formed by linking the poly(cis-l,4-isoprene) chain terminals to protein and phospholipid aggregates;after vulcanization,the natural network additionally contributes to rubber mechanics by both increasing the network density and promoting the strain-induced crystallization (SIC) ***,the reason why the natural network promotes SIC is still unclear;in particular,only using the increased network density cannot explain our finding that the NR shows smaller onset strain of SIC than Gel (the gel component of NR with higher network density) and even vulcanized ***,we point out that the inhomogeneous chain deformation is the alternative reason why SIC of NR takes place at smaller strain than that of *** specifically,although the natural network is homogenous on the subchain length scale based on the proton double-quantum NMR results,it is essentially inhomogeneous on mesoscale (100 nm),as revealed by the small angle X-ray scattering *** inhomogeneous network also leads to the mesoscale deformation inhomogeneity,as detected by the orientation of stearic acid (SA) probe,thus resulting in the smaller onset strain of SIC of *** on the experimental results,a mesoscale model is proposed to qualitatively describe the crucial roles of inhomogeneous structure and deformation of natural network in NR?s mechanical properties,providing a clue from nature to guide the development of high-performance rubbers with controlled structures at mesoscale.

关键词： Natural Rubber Inhomogeneous natural network Strain-induced crystallization Mesoscale model

Tough Semi-interpenetrating Polyvinylpyrrolidone/Polyacrylamide Hydrogels Enabled by Bioinspired Hydrogen-bonding Induced Phase Separation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第5期42卷 591-603,I0006页

作者： Qiong-Jun Xu Zhao-Yang Yuan Chang-Cheng Wang Hao Liang Yu Shi Hai-Tao wu Hu Xu jing Zheng jin-rong wu State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu610065China

Semi-interpenetrating(semi-IPN)hydrogels formed by the continuous interpenetration of cross-linked polymer network and linear non-crosslinked polymer with multifunctionality are widely used in biomedical and other ***,the negative impact of linear polymer on the homogeneity of the cross-linked network often leads to a decrease in the mechanical properties of semi-IPN hydrogels and severely limits their ***,a bioinspired hydrogen-bonding induced phase separation strategy is presented to construct the tough semi-IPN polyvinylpyrrolidone/polyacrylamide hydrogels(named PVP/PAM hydrogels),including the linear polymer polyvinylpyrrolidone(PVP)and cross-linked polyacrylamide(PAM)*** resultant PVPx/PAM hydrogels exhibit unique phase separation induced by the hydrogen bonding between PVP and PAM and affected by the amount of substance of ***,the phase separation of PVPx/PAM hydrogels results in excellent mechanical properties with a strain of 2590%,tensile strength of 0.28 MPa and toughness of 2.17 MJ/m^(3).More importantly,the hydrogen bonding between PVP and PAM firstly disrupts to dissipate energy under external forces,so the PVPx/PAM hydrogels exhibit good self-recovery properties and outperform chemically cross-linked PAM hydrogels in impact resistance and damping *** is believed that the PVPx/PAM hydrogels with hydrogen-bonding induced phase separation possess more potential application prospects.

关键词： Tough Semi-interpenetrating networks Polyvinylpyrrolidone/polyacrylamide Hydrogels Phase separation

Observation of pseudogap in SnSe2 atomic layers grown on graphite

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2020年第4期15卷 113-120页

作者： Ya-Hui Mao Huan Shan jin-rong wu Ze-Jun Li Chang-Zheng wu Xiao-Fang Zhai Ai-Di Zhao Bing Wang Hefei National Laboratory for Physical Sciences at the Microscale and Symergetic Innovation Center of Quantum Inforrnation and Quantum Physics University of Science and Technology of ChinaHefei 290026China School of Physical Science and Techrnology ShanghaiTech UniversityShanghai 201210China

Superconducting metal dichalcogenides(MDCs)present several similarities to the other layered SI1-perconductors like *** superconductivity in atomically thin MDCs has been demonstrated by recent experiments,however,the investigation of the superconductivity intertwined with other or-ders are *** the pseudogap in atomic layers of MDCs may help to understand the superconducting mechanism for these true two dimensional(2D)superconducting *** we report a pseudogap opening in the tunneling spectra of thin layers of SnSe2 epitaxially grown on highly oriented pyrolytic graphite(HOPG)with scanning tunneling microscopy/spectroscopy(STM/STS).A significant V-shaped pseudogap was observed to open near the Fermi level(Er)in the *** at elevated temperatures,the gap gradually evolves to a shallow *** experimental observations provide direct evidence of a pseudogap state in the electron-doped SnSe2 atomic layers on the HOPG surface,which may stimulate further exploration of the mechanism of superconductivity at 2D limit in MDCs.

关键词： scanning tunneling microscopy pseudogap metal dichalcogenides SnSe2 van der Waals epitaxy