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Robust microwave absorption in silver-cobalt hollow microspheres with heterointerfaces and electric-magnetic synergism:Towards achieving lightweight and absorption-type microwave shielding composites

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Journal of Materials Science & Technology 2023年第7期138卷 245-255页

作者： Dian Yang Jun-Ru Tao Yi Yang Qian-Ming He Ming Wang Chongqing key laboratory of soft-matter Material chemistry and Function Manufacturing School of Chemistry and Chemical EngineeringSouthwest UniversityChongqing 400715China

Lightweight and high-efficiency microwave shielding materials based on high absorption loss are the hotspot of current research.Herein,the silver-cobalt bimetallic hollow microspheres(Ag-Co-HM)with low reflection loss and broadband absorption efficiency were fabricated and then used to construct bimetallic hollow structures in polydimethylsiloxane/carbon nanotube composites(PDMS/CNT)to obtain the lightweight and absorption-type microwave shielding composites.The microwave absorption of Ag-Co-HM and the microwave shielding effectiveness(SE T)of the PDMS/CNT/Ag-Co-HM composites was evaluated and discussed.The Ag-Co-HM with a molar ratio(Co/Ag)of 2.07 exhibited a low reflection loss as-46.6 dB at a thickness of 2.6 mm,and an effective absorption bandwidth of 8.40 GHz.The SE T of the PDMS/CNT composites was greatly enhanced by the incorporation of the Ag-Co-HM.Furthermore,the absorption coefficient(A)was also improved by adding the Ag-Co-HM and was much higher than the reflection coefficient.The composites exhibited absorption-type microwave shielding composites.For example,the average microwave SE T of 59.4 dB and A value of 0.78 are achieved in the PDMS/CNT/Ag-Co-HM composites containing 5 wt%CNTs and 10 wt%Ag-Co-HMs,which are much higher than the cor-responding values of 33.7 dB and 0.63 in the PDMS/CNT composites with only 5 wt%CNTs.In addition,the hollow structure of Ag-Co-HM endows the PDMS/CNT/Ag-Co-HM composites to have a low density.

关键词： Microwave shielding Absorption loss Lightweight Polydimethylsiloxane Carbon nanotube

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Transpiration-prompted Photocatalytic Degradation of Dye Pollutant with AuNPs/PANI Based Cryogels

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Chinese Journal of Polymer Science 2022年第10期40卷 1141-1153,I0006,I0005页

作者： Xiao-Xiao Guo Shi-Chang Hou Jun Chen Cong Liao Wei-Dong He CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

Incautious discharge of organic dyes such as methyl orange(MO)has produced serious pollution to the environment,calling for the efficient techniques to remove them with retaining the green world.The photo-catalytic degradation of organic dyes is promising among the developed techniques.Thus,a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward.Aniline(ANI)is graft-polymerized onto poly(acrylamide-co-N-4-aminophenylacrylamide)(PAAm)cryogel embedded with gold nanoparticles(AuNPs,diameter:4-10 nm).The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix(AuNP@PAAm-g-PANI)have been structurally explored based on the chemical composition and the phase/porous morphology.SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix.Since the macro-porosity of cryogel,hydrophilicity of PAAm and photo-thermal activity of PANI,PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m^(-2)·h^(-1).As a comparison,Au NP@PAAm-g-PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m^(-2)·h^(-1),suggesting the promotion of AuNPs to photo-thermal evaporation.Meanwhile,PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO.Therefore,the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm-g-PANI cryogels,whose rate constant can reach to 0.320 h^(-1),being three folds of that for the sole absorption of MO.This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy.

关键词： Photothermal evaporation Photocatalytic degradation Sunlight Organic dye Composite cryogel

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Scalable preparation and direct visualization of cyclic polymers via self-folding cyclization technique

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Science China chemistry 2022年第12期65卷 2558-2566页

作者： Hualong Zhang Hao Zha Chao Liu Chunyan Hong CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei230026China

Cyclic polymers exhibit distinct properties compared with their linear counterparts due to the lack of chain ends.However,the scalable synthesis of cyclic polymers remains a major challenge,especially for ring-closure method.Herein,we report a novel strategy for large-scale preparation of cyclic polymers,which relies on the prior self-folding of anthracene-telechelic amphiphilic random copolymers(poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate)),P(OEGA-co-DDA))into single-chain polymeric nanoparticles(SCPNs)in water.Subsequent ultraviolet(UV)-induced cyclization occurs in the hydrophobic nano-domain.The formation of SCPNs leads to a shortened distance between the end groups of the linear precursors and spatially separated cyclization loci,and significantly enhances the efficiency of UV-induced cyclization.This self-folding technique permits access to the synthesis of cyclic polymers not only with high molecular weights(M_(n)>10^(5) g/mol),but also in a decent scale(40 g/L),breaking through the limitations of ring-closure method.Furthermore,the dense pendants of the copolymers can magnify the macromolecules by increasing the mass density along the backbones,thus making the polymers more readily detectable by the microscopy.The transmission electron microscopy(TEM)and atomic force microscopy(AFM)images allow us to observe the topological structures directly and provide crucial evidence to confirm the cyclization.

关键词： cyclic polymer scalable preparation direct visualization self-folding cyclization technique

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Synthesis of silicon-functionalized polyolefins by subsequent cobalt-catalyzed dehydrogenative silylation and nickel-catalyzed copolymerization

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Science Bulletin 2018年第7期63卷 441-445页

作者： Shixin Zhou Changle Chen Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China

Metal catalyzed olefin hydrosilylation and metal mediated olefin polymerization are both of great academic and industrial importance. In this article, these two aspects are combined to prepare siliconfunctionalized polyolefin materials. First, pyridine-diimine cobalt-catalyzed dehydrogenative silylations of various terminal olefins with alkylsilanes lead to the formation of a variety of allylsilanes at high yields.Then, the allylsilanes are copolymerized with ethylene using an a-diimine nickel catalyst, leading to the formation of branched polyolefins with high molecular weight and moderate comonomer incorporation.This subsequent catalytic process is an efficient strategy for the synthesis of silicon-functionalized polyolefins using widely available and inexpensive starting materials.

关键词：催化过程镍催化剂合成钴石蜡聚合金属材料

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一种基于二取代极性降冰片烯的策略用于解决极性单体共聚问题

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Science Bulletin 2021年第14期66卷 1429-1436,M0004页

作者：徐梦贺陈昶乐 Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

过渡金属催化烯烃与极性单体的共聚反应是制备功能化聚烯烃最直接的途径.极性官能团对金属中心的毒化和极性单体与非极性烯烃之间反应活性的差异使得高性能催化剂的开发依然具有很大的挑战性.本文从共聚单体的角度出发,使用廉价、易得的... 详细信息

过渡金属催化烯烃与极性单体的共聚反应是制备功能化聚烯烃最直接的途径.极性官能团对金属中心的毒化和极性单体与非极性烯烃之间反应活性的差异使得高性能催化剂的开发依然具有很大的挑战性.本文从共聚单体的角度出发,使用廉价、易得的5,6-二取代降冰片烯类单体与乙烯进行共聚,并且该单体能够在此过程中能够一次性插入2个极性官能团.更为重要的是,此类环状单体的优势在于其对金属中心较弱的毒化,同时也不易于发生β-氢消除反应.此外,π键的强供电子效应使得此类单体能够与乙烯形成有利的竞争配位.采用膦磺酸钯催化剂催化乙烯与5,6-二取代降冰片烯的共聚反应,进而制备出具有高活性、高聚合物分子量和高极性单体插入比的共聚物.在此过程中,还研究了工业溶剂的使用、极性单体本体中的共聚、极性单体的回收与再利用、共聚物分子量的调控、规模化的合成以及共聚物的性质等.

关键词：降冰片烯极性单体聚合物分子量工业溶剂共聚单体过渡金属催化钯催化剂消除反应

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Structure regulating of metal clusters in carbonized metallic organic frameworks for high-efficient microwave absorption via tuning interaction strength between metals and ligands

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Nano Research 2024年第3期17卷 1699-1709页

作者： Chang Sun Kun-Yan Zhao Ming-Lu Huang Cheng-Long Luo Xu-Dong Chen Ming Wang School of chemistry and Chemical Engineering Chongqing Key Laboratory of Soft-Matter Material Chemistry and Function ManufacturingSouthwest UniversityChongqing 400715China Jieyang Branch of chemistry and Chemical Engineering Guangdong laboratory(Rongjiang laboratory) Jieyang 515200China

Carbonized metallic organic frameworks(CMOF)have been attracting attention in microwave absorption(MA)research area because of their diverse structures,tunable compositions,and rich porosity.Herein,structure regulation on metal clusters in CMOF is achieved by tuning the interaction strength between metals and ligands to enhance microwave absorption performance.Due to relatively weak interaction among copper cations and ligands,copper nanoclusters(CuNC)can be uniformly formed and embedded within the cobalt/zinc(Co/Zn)CMOF.Firstly,copper cations are added to the Co/Zn bimetallic zeolitic imidazolate frameworks(ZIFs).Secondly,the CMOF composite particles with CuNCs(CuNCs/CoZn-CMOF)were developed by a pyrolysis process.The CuNCs/CoZn-CMOF with an appropriate amount of CuNCs can harmonize both dielectric and magnetic losses.As a result,the minimum reflection loss(RLmin)reaches–45.1 dB at a matching thickness of 2.30 mm and the effective absorption bandwidth(EAB)is 8.80 GHz at a thickness of 3.10 mm.The broadband response to electromagnetic waves is attributed to interfacial polarization at CuNCs surface and heterogeneous interfaces,impedance matching and multiple scattering of electromagnetic waves.This study provides a feasible method to develop CMOF microwave absorption materials with high EAB values.

关键词： heterogeneous interface carbonized metallic organic frameworks microwave absorption interfacial polarization

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A general cocatalyst strategy for performance enhancement in nickel catalyzed ethylene(co)polymerization

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Chinese Chemical Letters 2022年第9期33卷 4363-4366页

作者： Quan Wang Zhao Zhang Chen Zou Changle Chen CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

The tuning of olefin-polymerization catalyst properties through ligand modifications is efficient but requires complicated and costly syntheses.In this contribution,a simple Bu_(2)Mg-based cocatalyst strategy is designed that can simultaneously enhance the catalytic properties(activity,thermal stability,polymer molecular weight,branching density,melting point,etc.)of various nickel catalysts(α-diimine nickel,pyridine imine nickel and iminopyridine-N-oxide nickel)in ethylene polymerization,and enable great product morphology control.For example,a simpleα-diimine nickel catalyst can demonstrate polymerization activity of up to 1.29×10^(7)g mol^(−1)h^(−1)and molecular weight of up to 1.90×10^(6)g/mol in the presence of Bu_(2)Mg cocatalyst.The resulting polyethylenes exhibit excellent mechanical properties,with tensile stress of up to 47.4 MPa and strain of up to 1020%.This cocatalyst strategy is generally applicable to different nickel catalysts,and can lead to property enhancement in ethylene copolymerization with a series of polar comonomers such as methyl 10-undecylenate,10-undecylenic acid and 10-undecenol.

关键词： Nickel Cocatalyst Magnesium Ethylene polymerization

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Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

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Chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： Jing Lv Xu Chen Zi-Shuo Wu Ya-Hui Li Wei Chen National Synchrotron Radiation laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR techniques.The plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich domain.The time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific features.The quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is deuterated.The ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation measurements.The origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen bonding.Also,the existence of a mobility gradient in the VB unit has been demonstrated.Moreover,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first time.This indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

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Recyclable polythioesters and polydisulfides with near-equilibrium thermodynamics and dynamic covalent bonds

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Science China chemistry 2023年第3期66卷 725-738页

作者： Wei Xiong Hua Lu Beijing National laboratory for Molecular Sciences Center for Soft Matter Science and EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The accumulation of discarded petroleum-based plastics causes serious environmental crises.Currently,recyclable polymers with neutrality in thermodynamics,such as polyesters,polycarbonates,and polyolefins,have been developed as promising alternatives to traditional petroleum-based polymers.However,the chemical recycle of these polymers usually requires high energy input and expensive catalysts.Dynamic covalent bonds,such as thioester and disulfide bonds,have emerged as building blocks for constructing recyclable polymers that can be rapidly degraded/recycled under mild conditions.In this review,we introduce representative studies on recyclable polythioesters and polydisulfides with respect to their synthetic strategies,thermodynamic manipulation,physicochemical properties,and preliminary applications.We also highlight the important role of kinetic factors played in the design of recyclable polymers.Finally,major challenges,perspectives,and future opportunities in the synthesis and applications of polythioesters/polydisulfides are discussed.

关键词： polythioesters polydisulfides recyclable near-equilibrium thermodynamics dynamic covalent bond

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Advanced surface engineering of titanium materials for biomedical applications:From static modification to dynamic responsive regulation

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Bioactive Materials 2023年第9期27卷 15-57页

作者： Pinliang Jiang Yanmei Zhang Ren Hu Bin Shi Lihai Zhang Qiaoling Huang Yun Yang Peifu Tang Changjian Lin South China Advanced Institute for soft matter Science and Technology School of Emergent Soft MatterGuangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and DevicesSouth China University of TechnologyGuangzhou510640China State key Lab of Physical chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China Department of Orthopaedics General Hospital of Chinese PLABeijing100853China Research Institute for Biomimetics and soft matter Fujian Provincial Key Laboratory for Soft Functional Materials ResearchCollege of Physical Science and TechnologyXiamen UniversityXiamen361005China

Titanium(Ti)and its alloys have been widely used as orthopedic implants,because of their favorable mechanical properties,corrosion resistance and biocompatibility.Despite their significant success in various clinical applications,the probability of failure,degradation and revision is undesirably high,especially for the patients with low bone density,insufficient quantity of bone or osteoporosis,which renders the studies on surface modification of Ti still active to further improve clinical results.It is discerned that surface physicochemical properties directly influence and even control the dynamic interaction that subsequently determines the success or rejection of orthopedic implants.Therefore,it is crucial to endow bulk materials with specific surface properties of high bioactivity that can be performed by surface modification to realize the osseointegration.This article first reviews surface characteristics of Ti materials and various conventional surface modification techniques involving mechanical,physical and chemical treatments based on the formation mechanism of the modified coatings.Such conventional methods are able to improve bioactivity of Ti implants,but the surfaces with static state cannot respond to the dynamic biological cascades from the living cells and tissues.Hence,beyond traditional static design,dynamic responsive avenues are then emerging.The dynamic stimuli sources for surface functionalization can originate from environmental triggers or physiological triggers.In short,this review surveys recent developments in the surface engineering of Ti materials,with a specific emphasis on advances in static to dynamic functionality,which provides perspectives for improving bioactivity and biocompatibility of Ti implants.

关键词： Titanium materials Orthopedic implants Bioactivity Static modification Dynamic responsive regulation

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