With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivit...With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivity for radar antenna systems are urgently needed.Herein,a down-top strategy was employed to synthesize poly(p-phenylene benzobisoxazole)precursor nanofibers(prePNF).The prePNF was then uniformly mixed with fluorinated graphene(FG)to fabricate FG/PNF composite papers through consecutively suction filtration,hot-pressing,and thermal annealing.The hydroxyl and amino groups in prePNF enhanced the stability of FG/prePNF dispersion,while the increasedπ-πinteractions between PNF and FG after annealing improved their compatibility.The preparation time and cost of PNF paper was significantly reduced when applying this strategy,which enabled its large-scale production.Furthermore,the prepared FG/PNF composite papers exhibited excellent wave-transparent performance and thermal conductivity.When the mass fraction of FG was 40 wt%,the FG/PNF composite paper prepared via the down-top strategy achieved the wave-transparent coefficient(|T|2)of 96.3%under 10 GHz,in-plane thermal conductivity(λ_(∥))of 7.13 W m^(−1)K^(−1),and through-plane thermal conductivity(λ_(⊥))of 0.67 W m^(−1)K^(−1),outperforming FG/PNF composite paper prepared by the top-down strategy(|T|2=95.9%,λ_(∥)=5.52 W m^(−1)K^(−1),λ_(⊥)=0.52 W m^(−1)K^(−1))and pure PNF paper(|T|2=94.7%,λ_(∥)=3.04 W m^(−1)K^(−1),λ_(⊥)=0.24 W m^(−1)K^(−1)).Meanwhile,FG/PNF composite paper(with 40 wt%FG)through the down-top strategy also demonstrated outstanding mechanical properties with tensile strength and toughness reaching 197.4 MPa and 11.6 MJ m^(−3),respectively.展开更多
With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted world...With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted worldwide attention.Therefore,the design and development of highly efficient EMI shielding materials are of great importance.In this work,the three-dimensional graphene oxide(GO)with regular honeycomb structure(GH)is firstly constructed by sacrificial template and freeze-dry-ing methods.Then,the amino functionalized FeNi alloy particles(f-FeNi)are loaded on the GH skeleton followed by in-situ reduction to prepare rGH@FeNi aerogel.Finally,the rGH@FeNi/epoxy EMI shielding com-posites with regular honeycomb structure is obtained by vacuum-assisted impregnation of epoxy resin.Benefitting from the construction of regular honeycomb structure and electromagnetic synergistic effect,the rGH@FeNi/epoxy composites with a low rGH@FeNi mass fraction of 2.1 wt%(rGH and f-FeNi are 1.2 and 0.9 wt%,respectively)exhibit a high EMI shielding effectiveness(EMI SE)of 46 dB,which is 5.8 times of that(8 dB)for rGO/FeNi/epoxy composites with the same rGO/FeNi mass fraction.At the same time,the rGH@FeNi/epoxy composites also possess excellent thermal stability(heat-resistance index and temperature at the maximum decomposition rate are 179.1 and 389.0°C respectively)and mechanical properties(storage modulus is 8296.2 MPa).展开更多
The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in ...The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.展开更多
Poly(p-phenylenebenzobisoxazole)nanofibers(PNF),as a novel kind of nanofibers,have attracted significant attention from researchers.However,their poor ultraviolet(UV)resistance limits their potential applications.In t...Poly(p-phenylenebenzobisoxazole)nanofibers(PNF),as a novel kind of nanofibers,have attracted significant attention from researchers.However,their poor ultraviolet(UV)resistance limits their potential applications.In this work,zinc oxide(ZnO)was uniformly coated on the surface of PNF-containing polysilsesquioxane(POSS)via in-situ growth to obtain(POSS-PNF)@ZnO.Subsequently,(POSS-PNF)@ZnO wave-transparent composite paper was then fabricated using a“vacuum filtration-assisted hot-pressing”method.Based on the coordination interaction between O–Cdouble bondO groups of PNFs and ZnO,as well as the UV absorption/shielding capability of ZnO,the(POSS-PNF)@ZnO wave-transparent composite paper exhibited superior mechanical properties and UV resistance.At a hydrothermal reaction temperature of 80℃,the prepared(POSS-PNF)@ZnO wave-transparent composite paper exhibited the highest tensile strength(204.5 MPa)and toughness(12.3 MJ m^(−3)),which represents increases of 23.7%and 32.3%,respectively,compared to POSS-PNF wave-transparent paper.After 288 h of UV aging,the tensile strength retention rate was 77.4%,significantly higher than the 53.7%of POSS-PNF wave-transparent composite paper.Moreover,it exhibited excellent wave-transparent performance with a dielectric constant(ε)of 2.15 and a dielectric loss tangent(tanδ)of 0.044 at 10 GHz,resulting in a wave-transparent coefficient of 95.9%.展开更多
A series of divinylphenyl-acryloyl chloride copolymers(PDVB-co-PACl)is synthesized via atom transfer radical polymerization employing tert-butyl acrylate and divinylbenzene as monomers.PDVB-co-PACl is utilized to graf...A series of divinylphenyl-acryloyl chloride copolymers(PDVB-co-PACl)is synthesized via atom transfer radical polymerization employing tert-butyl acrylate and divinylbenzene as monomers.PDVB-co-PACl is utilized to graft on the surface of spherical aluminum nitride(AlN)to prepare functionalized AlN(AlN@PDVB-co-PACl).Polymethylhydrosiloxane(PMHS)is then used as the matrix to prepare thermally conductive AlN@PDVB-co-PACl/PMHS composites with AlN@PDVB-co-PACl as fillers through blending and curing.The grafting of PDVB-co-PACl synchronously enhances the hydrolysis resistance of AlN and its interfacial compatibility with PMHS matrix.When the molecular weight of PDVB-co-PACl is 5100 g mol^(-1)and the grafting density is 0.8 wt%,the composites containing 75 wt%of AlN@PDVB-co-PACl exhibit the optimal comprehensive performance.The thermal conductivity(λ)of the composite is 1.14 W m^(-1)K^(-1),which enhances by 20%and 420%compared to theλof simply physically blended AlN/PMHS composite and pure PMHS,respectively.Meanwhile,AlN@PDVB-co-PACl/PMHS composites display remarkable hydrothermal aging resistance by retaining 99.1%of itsλafter soaking in 90°C deionized water for 80 h,whereas theλof the blended AlN/PMHS composites decreases sharply to 93.7%.展开更多
The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to...The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to their single-functionalities.Herein,a combined Prussian blue analogues derived and catalytical chemical vapor deposition strategy was proposed to produce hierarchical cubic sea urchin-like yolk–shell CoNi@Ndoped carbon(NC)-CoNi@carbon nanotubes(CNTs)mixed-dimensional multicomponent nanocomposites(MCNCs),which were composed of zerodimensional CoNi nanoparticles,three-dimensional NC nanocubes and onedimensional CNTs.Because of good impedance matching and attenuation characteristics,the designed CoNi@NC-CoNi@CNTs mixed-dimensional MCNCs exhibited excellent MA performances,which achieved a minimum reflection loss(RL_(min))of−71.70 dB at 2.78 mm and Radar Cross section value of−53.23 dB m^(2).More importantly,the acquired results demonstrated that CoNi@NC-CoNi@CNTs MCNCs presented excellent photothermal,antimicrobial and anti-corrosion properties owing to their hierarchical cubic sea urchin-like yolk–shell structure,highlighting their potential multifunctional applications.It could be seen that this finding not only presented a generalizable route to produce hierarchical cubic sea urchin-like yolk–shell magnetic NC-CNTs-based mixed-dimensional MCNCs,but also provided an effective strategy to develop multifunctional MCNCs and improve their environmental adaptabilities.展开更多
High-performance Ti_(3)C_(2)T_(x)fibers have garnered significant potential for smart fibers enabled fabrics.Nonetheless,a major challenge hindering their widespread use is the lack of strong interlayer interactions b...High-performance Ti_(3)C_(2)T_(x)fibers have garnered significant potential for smart fibers enabled fabrics.Nonetheless,a major challenge hindering their widespread use is the lack of strong interlayer interactions between Ti_(3)C_(2)T_(x)nanosheets within fibers,which restricts their properties.Herein,a versatile strategy is proposed to construct wet-spun Ti_(3)C_(2)T_(x)fibers,in which trace amounts of borate form strong interlayer crosslinking between Ti_(3)C_(2)T_(x)nanosheets to significantly enhance interactions as supported by density functional theory calculations,thereby reducing interlayer spacing,diminishing microscopic voids and promoting orientation of the nanosheets.The resultant Ti_(3)C_(2)T_(x)fibers exhibit exceptional electrical conductivity of 7781 S cm^(-1)and mechanical properties,including tensile strength of 188.72 MPa and Young's modulus of 52.42 GPa.Notably,employing equilibrium molecular dynamics simulations,finite element analysis,and cross-wire geometry method,it is revealed that such crosslinking also effectively lowers interfacial thermal resistance and ultimately elevates thermal conductivity of Ti_(3)C_(2)T_(x)fibers to 13 W m^(-1)K^(-1),marking the first systematic study on thermal conductivity of Ti_(3)C_(2)T_(x)fibers.The simple and efficient interlayer crosslinking enhancement strategy not only enables the construction of thermal conductivity Ti_(3)C_(2)T_(x)fibers with high electrical conductivity for smart textiles,but also offers a scalable approach for assembling other nanomaterials into multifunctional fibers.展开更多
Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a n...Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.展开更多
In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required t...In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required to attenuate electromagnetic wave energy.In this work,the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide(NaOH)/urea solution,and cellulose aerogels(CA)are prepared by gelation and freeze-drying.Then,the cellulose carbon aerogel@reduced graphene oxide aerogels(CCA@rGO)are prepared by vacuum impregnation,freeze-drying followed by thermal annealing,and finally,the CCA@rGO/polydimethylsiloxane(PDMS)EMI shielding composites are prepared by backfilling with PDMS.Owing to skin-core structure of CCA@rGO,the complete three-dimensional(3D)double-layer con-ductive network can be successfully constructed.When the loading of CCA@rGO is 3.05 wt%,CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness(EMI SE)of 51 dB,which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites(13 dB)with the same loading of fillers.At this time,the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability(T_(HRI)of 178.3℃)and good thermal conductivity coefficient(λof 0.65 W m^(-1)K^(-1)).Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight,flexible EMI shielding composites.展开更多
Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)c...Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)composites with hollow cavity,multiple hetero-interfaces,and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction.In the sandwich composites,middle magnetic components(Co/NC)are wrapped by inner N-doped carbon(NC)matrix and outer hierarchical MnO_(2)nanosheets.Importantly,hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity.The maximum reflection loss of sandwich NC@Co/NC@MnO_(2)composites reaches-44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm.These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.展开更多
With the rapid development of electronic information technology,antenna systems in the fields of aviation,aerospace,transportation,and 5 G communication services are becoming more and more intensive and accurate.Polym...With the rapid development of electronic information technology,antenna systems in the fields of aviation,aerospace,transportation,and 5 G communication services are becoming more and more intensive and accurate.Polymer matrix wave-transparent composites with lightweight,low dielectric constant(∈)and dielectric loss tangent(tanδ),high temperature resistance,and excellent mechanical properties are urgently needed in order to ensure high-fidelity transmission of electromagnetic wave and protect antenna systems from external interference.This review introduces the wave transmission mechanism,key compositions(polymer matrix&reinforced fibers),and several typical testing methods for dielectric properties of polymer matrix wave-transparent composites,mainly elaborates the latest research progress and achievements of polymer matrix wave-transparent composites from polymer matrix,reinforced fibers and their surface functionalization methods,and presents the key scientific and technical problems that need to be solved urgently in the application of polymer matrix wave-transparent composites in the antenna systems.Finally,the future development trends and application prospects of the polymer matrix wave-transparent composites are also proposed.展开更多
The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based elect...The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based electromagnetic interference(EMI)shielding composites.However,most of currently prepared polymer-based EMI shielding composites are still difficult to combine high performance and multi-functionality.In response to this,based on the research works of relevant researchers as well as our research group,three possible directions to break through the above bottlenecks are proposed,including construction of efficient conductive networks,optimization of multi-interfaces for lightweight and multifunction compatibility design.The future development trends in three directions are prospected,and it is hoped to provide certain theoretical basis and technical guidance for the preparation,research and development of polymer-based EMI shielding composites.展开更多
Increasingly severe electromagnetic pollution is now in urgent need of materials with lightweight,excellent flame retardancy,and outstanding electromagnetic interference shielding effectiveness(EMI SE).Renewable sourc...Increasingly severe electromagnetic pollution is now in urgent need of materials with lightweight,excellent flame retardancy,and outstanding electromagnetic interference shielding effectiveness(EMI SE).Renewable source-derived carbon foams and graphene have attracted extensive attention due to their 3D porous structure and remarkable electrical conductivity().In this work,annealed sugarcane(ASC)was prepared by removal of lignin from sugarcane via hydrothermal reaction,followed by annealing treatment.Then graphene oxide(GO)was filled by vacuum-assisted impregnation process and thermally annealed to obtain the ASC/reduced graphene oxide(rGO)hybrid foams.When the loading of rGO is 17 wt.%,the ASC/rGO hybrid foam(density,of 0.047 g/cm^3)exhibits the optimal of 6.0 S/cm,EMI SE of 53 dB,specific SE(SSE=SE/)/thickness(t)of 3830 dB·cm^2/g,and compressive strength of 1.33 MPa,which is 76%,36%,13%and 6%higher than those of ASC,respectively.Moreover,ASC/rGO presents excellent flame retardancy,thermal stability,and heat insulation,which remains constant under burning on an alcohol lamp and presents low thermal conductivity of 115.19 mW(m·K),close to the requirement for heat insulation.Synergistic effect of ASC and rGO not only significantly increase of ASC/rGO,but fully utilizes the capability of ASC and rGO to attenuate electromagnetic waves by virtue of unique porous structures and abundant interfaces.Such kind of lightweight EMI materials with excellent mechanical property,shielding performance,flame retardancy,and heat insulation is expected to tackle the key scientific and technical bottleneck problems of EMI materials,and will greatly expand the application of carbon nanomaterials in the field of aerospace industry.展开更多
Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)va...Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer composites.Aimed at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental optimization.Also,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.展开更多
With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materia...With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.展开更多
High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(...High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x)and Fe_(3)O_(4)are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x)and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index)of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.展开更多
MXene presents excellent electrical conductivity,abundant surface functional groups and wonderful filmforming performance,but the lamellar layers are prone to self-stacking during film formation,which will reduce the ...MXene presents excellent electrical conductivity,abundant surface functional groups and wonderful filmforming performance,but the lamellar layers are prone to self-stacking during film formation,which will reduce the loss of electromagnetic waves,hinder ion transmission,and limit the effective load of other functional materials.The construction of the porous structure can effectively solve the self-stacking problem of MXene sheets.This article reviews the research progress of MXene porous films for electromagnetic interference(EMI)shielding,lithium/sodium ion batteries,pseudocapacitors,and biomedical science applications.It focuses on the preparation methods of MXene porous films,and discusses the pore-forming mechanism of the porous structure formed by different preparation methods and the internal relationship between the“microstructure-macroscopic performance”of the MXene porous films,points out the key scientific and technical bottlenecks that need to be solved urgently in the preparation and application of the MXene porous films.It is hoped to provide certain guidance for the design,preparation,optimization,industrial application,and development of MXene porous films.展开更多
One kind of side chain liquid crystal epoxy(S-LCE)based on biphenyl mesomorphic unit is synthesized from 2,2-bis(hydroxymethyl)propionic acid,4-phenyl phenol,and epichlorohydrin.And the intrinsic thermal conductive li...One kind of side chain liquid crystal epoxy(S-LCE)based on biphenyl mesomorphic unit is synthesized from 2,2-bis(hydroxymethyl)propionic acid,4-phenyl phenol,and epichlorohydrin.And the intrinsic thermal conductive liquid crystal epoxy film(LCEF)simultaneously combining with intrinsic self-healing performance is then prepared via thiol-epoxide nucleophilic ring-opening reaction and coating method.1 H NMR and FTIR show that S-LCE and LCEF have been successfully prepared.S-LCE presents nematic liquid crystal from room temperature to 160℃.LCEF maintains nematic liquid crystal performance and shows highly intrinsic thermal conductivity&excellent self-healing performance.Thermal conductivity coefficient(λ)values in vertical direction(λ⊥)and parallel direction(λ‖)of LCEF are 0.33 and 1.25 W/mK,re spectively,much higher than that of general bisphenol A epoxy resin(E-51,λ⊥of 0.19 W/mK andλ‖of0.65 W/mK).Tensile strength of LCEF is 10.6 MPa,which can maintain at 90.6%and 61.3%after one and four cycles of self-healing behavior,respectively.In addition,LCEF presents a wide service temperature range(-9.8-251℃)and good thermal stability(THRI of 148.5℃).Simultaneously,LCEF has good transparency,flexibility,and tailorability,expected to be utilized in the fields of flexible electronic devices and intelligent structures.展开更多
Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&elec...Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).展开更多
基金the support from the National Natural Science Foundation of China(52473083,52373089,52403085)Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)+2 种基金the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57)Natural Science Basic Research Plan in Shaanxi Province of China(2024JC-YBMS-279)Natural Science Foundation of Chongqing,China(2023NSCQMSX2547)
文摘With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivity for radar antenna systems are urgently needed.Herein,a down-top strategy was employed to synthesize poly(p-phenylene benzobisoxazole)precursor nanofibers(prePNF).The prePNF was then uniformly mixed with fluorinated graphene(FG)to fabricate FG/PNF composite papers through consecutively suction filtration,hot-pressing,and thermal annealing.The hydroxyl and amino groups in prePNF enhanced the stability of FG/prePNF dispersion,while the increasedπ-πinteractions between PNF and FG after annealing improved their compatibility.The preparation time and cost of PNF paper was significantly reduced when applying this strategy,which enabled its large-scale production.Furthermore,the prepared FG/PNF composite papers exhibited excellent wave-transparent performance and thermal conductivity.When the mass fraction of FG was 40 wt%,the FG/PNF composite paper prepared via the down-top strategy achieved the wave-transparent coefficient(|T|2)of 96.3%under 10 GHz,in-plane thermal conductivity(λ_(∥))of 7.13 W m^(−1)K^(−1),and through-plane thermal conductivity(λ_(⊥))of 0.67 W m^(−1)K^(−1),outperforming FG/PNF composite paper prepared by the top-down strategy(|T|2=95.9%,λ_(∥)=5.52 W m^(−1)K^(−1),λ_(⊥)=0.52 W m^(−1)K^(−1))and pure PNF paper(|T|2=94.7%,λ_(∥)=3.04 W m^(−1)K^(−1),λ_(⊥)=0.24 W m^(−1)K^(−1)).Meanwhile,FG/PNF composite paper(with 40 wt%FG)through the down-top strategy also demonstrated outstanding mechanical properties with tensile strength and toughness reaching 197.4 MPa and 11.6 MJ m^(−3),respectively.
基金supports from the National Natural Science Foundation of China(U21A2093 and 51903145)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)and Fundamental Research Funds for the Central Universities(D5000210627)This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted worldwide attention.Therefore,the design and development of highly efficient EMI shielding materials are of great importance.In this work,the three-dimensional graphene oxide(GO)with regular honeycomb structure(GH)is firstly constructed by sacrificial template and freeze-dry-ing methods.Then,the amino functionalized FeNi alloy particles(f-FeNi)are loaded on the GH skeleton followed by in-situ reduction to prepare rGH@FeNi aerogel.Finally,the rGH@FeNi/epoxy EMI shielding com-posites with regular honeycomb structure is obtained by vacuum-assisted impregnation of epoxy resin.Benefitting from the construction of regular honeycomb structure and electromagnetic synergistic effect,the rGH@FeNi/epoxy composites with a low rGH@FeNi mass fraction of 2.1 wt%(rGH and f-FeNi are 1.2 and 0.9 wt%,respectively)exhibit a high EMI shielding effectiveness(EMI SE)of 46 dB,which is 5.8 times of that(8 dB)for rGO/FeNi/epoxy composites with the same rGO/FeNi mass fraction.At the same time,the rGH@FeNi/epoxy composites also possess excellent thermal stability(heat-resistance index and temperature at the maximum decomposition rate are 179.1 and 389.0°C respectively)and mechanical properties(storage modulus is 8296.2 MPa).
基金support from the National Natural Science Foundation of China(22268025,52473083,and 22475176)Key Research and Development Program of Yunnan Province(202403AP140036)+2 种基金Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)Applied Basic Research Program of Yunnan Province(202201AT070115 and 202201BE070001-031)supported by the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57).
文摘The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.
基金funding from the Foundation of the National Natural Science Foundation of China(Nos.52373089 and 52403085)the Startup Foundation of Chongqing Normal University(No.23XLB011)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202300561)Undergraduate Innovation&Business Program in Northwestern Polytechnical University(No.S202410699657)。
文摘Poly(p-phenylenebenzobisoxazole)nanofibers(PNF),as a novel kind of nanofibers,have attracted significant attention from researchers.However,their poor ultraviolet(UV)resistance limits their potential applications.In this work,zinc oxide(ZnO)was uniformly coated on the surface of PNF-containing polysilsesquioxane(POSS)via in-situ growth to obtain(POSS-PNF)@ZnO.Subsequently,(POSS-PNF)@ZnO wave-transparent composite paper was then fabricated using a“vacuum filtration-assisted hot-pressing”method.Based on the coordination interaction between O–Cdouble bondO groups of PNFs and ZnO,as well as the UV absorption/shielding capability of ZnO,the(POSS-PNF)@ZnO wave-transparent composite paper exhibited superior mechanical properties and UV resistance.At a hydrothermal reaction temperature of 80℃,the prepared(POSS-PNF)@ZnO wave-transparent composite paper exhibited the highest tensile strength(204.5 MPa)and toughness(12.3 MJ m^(−3)),which represents increases of 23.7%and 32.3%,respectively,compared to POSS-PNF wave-transparent paper.After 288 h of UV aging,the tensile strength retention rate was 77.4%,significantly higher than the 53.7%of POSS-PNF wave-transparent composite paper.Moreover,it exhibited excellent wave-transparent performance with a dielectric constant(ε)of 2.15 and a dielectric loss tangent(tanδ)of 0.044 at 10 GHz,resulting in a wave-transparent coefficient of 95.9%.
基金support from the National Natural Science Foundation of China(52473083 and 52403112)the Technological Base Scientific Research Projects(Highly Thermal conductivity Nonmetal Materials),the Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)+4 种基金the Shaanxi Province Key Research and Development Plan Project(2023-YBGY-461)the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57),the Natural Science Foundation of Chongqing,China(2023NSCQ-MSX2547)the Fundamental Research Funds for the Central Universities(D5000240077 and D5000240067)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2024094)the Analytical&Testing Center of Northwestern Polytechnical University for FT-IR,XRD and TEM tests performed in this work.
文摘A series of divinylphenyl-acryloyl chloride copolymers(PDVB-co-PACl)is synthesized via atom transfer radical polymerization employing tert-butyl acrylate and divinylbenzene as monomers.PDVB-co-PACl is utilized to graft on the surface of spherical aluminum nitride(AlN)to prepare functionalized AlN(AlN@PDVB-co-PACl).Polymethylhydrosiloxane(PMHS)is then used as the matrix to prepare thermally conductive AlN@PDVB-co-PACl/PMHS composites with AlN@PDVB-co-PACl as fillers through blending and curing.The grafting of PDVB-co-PACl synchronously enhances the hydrolysis resistance of AlN and its interfacial compatibility with PMHS matrix.When the molecular weight of PDVB-co-PACl is 5100 g mol^(-1)and the grafting density is 0.8 wt%,the composites containing 75 wt%of AlN@PDVB-co-PACl exhibit the optimal comprehensive performance.The thermal conductivity(λ)of the composite is 1.14 W m^(-1)K^(-1),which enhances by 20%and 420%compared to theλof simply physically blended AlN/PMHS composite and pure PMHS,respectively.Meanwhile,AlN@PDVB-co-PACl/PMHS composites display remarkable hydrothermal aging resistance by retaining 99.1%of itsλafter soaking in 90°C deionized water for 80 h,whereas theλof the blended AlN/PMHS composites decreases sharply to 93.7%.
基金support from the National Natural Science Foundation of China(U21A2093)Shaanxi Province Key Research and Development Plan Project(2023-YBGY-461)+4 种基金Platform of Science and Technology and Talent Team Plan of Guizhou province(GCC[2023]007)Guizhou Provincial Basic Research Program(Natural Science)(No.ZK[2025]Key 086)Fok Ying Tung Education Foundation(171095)financial support,Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2024094)。
文摘The previous studies mainly focused on improving microwave absorbing(MA)performances of MA materials.Even so,these designed MA materials were very difficult to be employed in complex and changing environments owing to their single-functionalities.Herein,a combined Prussian blue analogues derived and catalytical chemical vapor deposition strategy was proposed to produce hierarchical cubic sea urchin-like yolk–shell CoNi@Ndoped carbon(NC)-CoNi@carbon nanotubes(CNTs)mixed-dimensional multicomponent nanocomposites(MCNCs),which were composed of zerodimensional CoNi nanoparticles,three-dimensional NC nanocubes and onedimensional CNTs.Because of good impedance matching and attenuation characteristics,the designed CoNi@NC-CoNi@CNTs mixed-dimensional MCNCs exhibited excellent MA performances,which achieved a minimum reflection loss(RL_(min))of−71.70 dB at 2.78 mm and Radar Cross section value of−53.23 dB m^(2).More importantly,the acquired results demonstrated that CoNi@NC-CoNi@CNTs MCNCs presented excellent photothermal,antimicrobial and anti-corrosion properties owing to their hierarchical cubic sea urchin-like yolk–shell structure,highlighting their potential multifunctional applications.It could be seen that this finding not only presented a generalizable route to produce hierarchical cubic sea urchin-like yolk–shell magnetic NC-CNTs-based mixed-dimensional MCNCs,but also provided an effective strategy to develop multifunctional MCNCs and improve their environmental adaptabilities.
基金the support from the National Natural Science Foundation of China(52403112,52473083)Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)+2 种基金the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57)Fundamental Research Funds for the Central Universities(D5000240062,D5000240077)Undergraduate Innovation&Business Program in Northwestern Polytechnical University(202410699041)。
文摘High-performance Ti_(3)C_(2)T_(x)fibers have garnered significant potential for smart fibers enabled fabrics.Nonetheless,a major challenge hindering their widespread use is the lack of strong interlayer interactions between Ti_(3)C_(2)T_(x)nanosheets within fibers,which restricts their properties.Herein,a versatile strategy is proposed to construct wet-spun Ti_(3)C_(2)T_(x)fibers,in which trace amounts of borate form strong interlayer crosslinking between Ti_(3)C_(2)T_(x)nanosheets to significantly enhance interactions as supported by density functional theory calculations,thereby reducing interlayer spacing,diminishing microscopic voids and promoting orientation of the nanosheets.The resultant Ti_(3)C_(2)T_(x)fibers exhibit exceptional electrical conductivity of 7781 S cm^(-1)and mechanical properties,including tensile strength of 188.72 MPa and Young's modulus of 52.42 GPa.Notably,employing equilibrium molecular dynamics simulations,finite element analysis,and cross-wire geometry method,it is revealed that such crosslinking also effectively lowers interfacial thermal resistance and ultimately elevates thermal conductivity of Ti_(3)C_(2)T_(x)fibers to 13 W m^(-1)K^(-1),marking the first systematic study on thermal conductivity of Ti_(3)C_(2)T_(x)fibers.The simple and efficient interlayer crosslinking enhancement strategy not only enables the construction of thermal conductivity Ti_(3)C_(2)T_(x)fibers with high electrical conductivity for smart textiles,but also offers a scalable approach for assembling other nanomaterials into multifunctional fibers.
基金support from the National Nat-ural Science Foundation of China(No.52403114)the Technolog-ical Base Scientific Research Projects(Highly Thermally Conduc-tive Nonmetal Materials)+3 种基金the Innovation Capability Support Pro-gram of Shaanxi(No.2024RS-CXTD-57)the Natural Science Foun-dation of Chongqing(No.2023NSCQ-MSX2547)the Fundamental Research Funds for the Central Universities(No.D5000240077)the Shaanxi Coal Chemical Industry Technology Research In-stitute Co.,Ltd.(No.2023YJY-Y-HZ-XS-NX003).
文摘Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.
基金the Foundation of National Natural Science Foundation of China(51773169 and 51973173)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(2020JQ-164)Y.Q.Guo thanks the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required to attenuate electromagnetic wave energy.In this work,the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide(NaOH)/urea solution,and cellulose aerogels(CA)are prepared by gelation and freeze-drying.Then,the cellulose carbon aerogel@reduced graphene oxide aerogels(CCA@rGO)are prepared by vacuum impregnation,freeze-drying followed by thermal annealing,and finally,the CCA@rGO/polydimethylsiloxane(PDMS)EMI shielding composites are prepared by backfilling with PDMS.Owing to skin-core structure of CCA@rGO,the complete three-dimensional(3D)double-layer con-ductive network can be successfully constructed.When the loading of CCA@rGO is 3.05 wt%,CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness(EMI SE)of 51 dB,which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites(13 dB)with the same loading of fillers.At this time,the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability(T_(HRI)of 178.3℃)and good thermal conductivity coefficient(λof 0.65 W m^(-1)K^(-1)).Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight,flexible EMI shielding composites.
基金support from the National Natural Science Foundation of China(No.U21A2093)Natural Science Foundation of Shaanxi Province(No.2022JM-260)Fundamental Research Funds for the Central Universities(No.G2022KY05109).This work is also financially supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.We would like to thank Zhang San from Shiyanjia Lab(www.shiyanjia.com)for the VSM analysis.
文摘Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption,but still remain the formidable challenges in decreasing filler loadings.Herein,sandwich NC@Co/NC@MnO_(2)composites with hollow cavity,multiple hetero-interfaces,and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction.In the sandwich composites,middle magnetic components(Co/NC)are wrapped by inner N-doped carbon(NC)matrix and outer hierarchical MnO_(2)nanosheets.Importantly,hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity.The maximum reflection loss of sandwich NC@Co/NC@MnO_(2)composites reaches-44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm.These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.
基金the support and funding from National Scientific Research Project(Basis Strengthening Plan)Space Supporting Fund from China Aerospace Science and Industry Corporation(2020-HT-XG)+4 种基金Fundamental Research Funds for the Central Universities(310201911qd003)China Postdoctoral Science Foundation(2019M653735)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials from Donghua University(KF2001)Open Fund from Henan University of Science and Technology(2020-RSC02)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the rapid development of electronic information technology,antenna systems in the fields of aviation,aerospace,transportation,and 5 G communication services are becoming more and more intensive and accurate.Polymer matrix wave-transparent composites with lightweight,low dielectric constant(∈)and dielectric loss tangent(tanδ),high temperature resistance,and excellent mechanical properties are urgently needed in order to ensure high-fidelity transmission of electromagnetic wave and protect antenna systems from external interference.This review introduces the wave transmission mechanism,key compositions(polymer matrix&reinforced fibers),and several typical testing methods for dielectric properties of polymer matrix wave-transparent composites,mainly elaborates the latest research progress and achievements of polymer matrix wave-transparent composites from polymer matrix,reinforced fibers and their surface functionalization methods,and presents the key scientific and technical problems that need to be solved urgently in the application of polymer matrix wave-transparent composites in the antenna systems.Finally,the future development trends and application prospects of the polymer matrix wave-transparent composites are also proposed.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(U21A2093)Y.L.Zhang would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)+1 种基金This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin ScholarsOpen access funding provided by Shanghai Jiao Tong University
文摘The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based electromagnetic interference(EMI)shielding composites.However,most of currently prepared polymer-based EMI shielding composites are still difficult to combine high performance and multi-functionality.In response to this,based on the research works of relevant researchers as well as our research group,three possible directions to break through the above bottlenecks are proposed,including construction of efficient conductive networks,optimization of multi-interfaces for lightweight and multifunction compatibility design.The future development trends in three directions are prospected,and it is hoped to provide certain theoretical basis and technical guidance for the preparation,research and development of polymer-based EMI shielding composites.
基金financially supported by the National Natural Science Foundation of China(No.51973173)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(No.2019JC-11)the Space Supporting Fund from China Aerospace Science and Industry Corporation(No.2020-HT-XG and 2019-HT-XG)。
文摘Increasingly severe electromagnetic pollution is now in urgent need of materials with lightweight,excellent flame retardancy,and outstanding electromagnetic interference shielding effectiveness(EMI SE).Renewable source-derived carbon foams and graphene have attracted extensive attention due to their 3D porous structure and remarkable electrical conductivity().In this work,annealed sugarcane(ASC)was prepared by removal of lignin from sugarcane via hydrothermal reaction,followed by annealing treatment.Then graphene oxide(GO)was filled by vacuum-assisted impregnation process and thermally annealed to obtain the ASC/reduced graphene oxide(rGO)hybrid foams.When the loading of rGO is 17 wt.%,the ASC/rGO hybrid foam(density,of 0.047 g/cm^3)exhibits the optimal of 6.0 S/cm,EMI SE of 53 dB,specific SE(SSE=SE/)/thickness(t)of 3830 dB·cm^2/g,and compressive strength of 1.33 MPa,which is 76%,36%,13%and 6%higher than those of ASC,respectively.Moreover,ASC/rGO presents excellent flame retardancy,thermal stability,and heat insulation,which remains constant under burning on an alcohol lamp and presents low thermal conductivity of 115.19 mW(m·K),close to the requirement for heat insulation.Synergistic effect of ASC and rGO not only significantly increase of ASC/rGO,but fully utilizes the capability of ASC and rGO to attenuate electromagnetic waves by virtue of unique porous structures and abundant interfaces.Such kind of lightweight EMI materials with excellent mechanical property,shielding performance,flame retardancy,and heat insulation is expected to tackle the key scientific and technical bottleneck problems of EMI materials,and will greatly expand the application of carbon nanomaterials in the field of aerospace industry.
基金National Natural Science Foundation of China(51773169 and 51973173)Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)+2 种基金Technological Base Scientific Research ProjectsNatural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC-11)Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer composites.Aimed at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental optimization.Also,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.
基金funding from the Foundation of National Natural Science Foundation of China(51903145 and 51973173)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+1 种基金Fundamental Research Funds for the Central Universities(D5000210627)This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(U21A2093 and 52203100)Y.L.Zhang would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)。
文摘High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x)and Fe_(3)O_(4)are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x)and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index)of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.
基金support and funding from the Foundation of National Natural Science Foundation of China(51903145 and 51973173)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+2 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2020JQ-164)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘MXene presents excellent electrical conductivity,abundant surface functional groups and wonderful filmforming performance,but the lamellar layers are prone to self-stacking during film formation,which will reduce the loss of electromagnetic waves,hinder ion transmission,and limit the effective load of other functional materials.The construction of the porous structure can effectively solve the self-stacking problem of MXene sheets.This article reviews the research progress of MXene porous films for electromagnetic interference(EMI)shielding,lithium/sodium ion batteries,pseudocapacitors,and biomedical science applications.It focuses on the preparation methods of MXene porous films,and discusses the pore-forming mechanism of the porous structure formed by different preparation methods and the internal relationship between the“microstructure-macroscopic performance”of the MXene porous films,points out the key scientific and technical bottlenecks that need to be solved urgently in the preparation and application of the MXene porous films.It is hoped to provide certain guidance for the design,preparation,optimization,industrial application,and development of MXene porous films.
基金support and funding from Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)National Natural Science Foundation of China(51773169 and 51973173)+3 种基金Fundamental Research Funds for the Central Universities(310201911py010)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC-11)Open Fund from Henan University of Science and Technology(2020-RSC01)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX201920)。
文摘One kind of side chain liquid crystal epoxy(S-LCE)based on biphenyl mesomorphic unit is synthesized from 2,2-bis(hydroxymethyl)propionic acid,4-phenyl phenol,and epichlorohydrin.And the intrinsic thermal conductive liquid crystal epoxy film(LCEF)simultaneously combining with intrinsic self-healing performance is then prepared via thiol-epoxide nucleophilic ring-opening reaction and coating method.1 H NMR and FTIR show that S-LCE and LCEF have been successfully prepared.S-LCE presents nematic liquid crystal from room temperature to 160℃.LCEF maintains nematic liquid crystal performance and shows highly intrinsic thermal conductivity&excellent self-healing performance.Thermal conductivity coefficient(λ)values in vertical direction(λ⊥)and parallel direction(λ‖)of LCEF are 0.33 and 1.25 W/mK,re spectively,much higher than that of general bisphenol A epoxy resin(E-51,λ⊥of 0.19 W/mK andλ‖of0.65 W/mK).Tensile strength of LCEF is 10.6 MPa,which can maintain at 90.6%and 61.3%after one and four cycles of self-healing behavior,respectively.In addition,LCEF presents a wide service temperature range(-9.8-251℃)and good thermal stability(THRI of 148.5℃).Simultaneously,LCEF has good transparency,flexibility,and tailorability,expected to be utilized in the fields of flexible electronic devices and intelligent structures.
基金support and funding from Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)National Natural Science Foundation of China(51773169 and 51973173)+3 种基金Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC11)Open Fund from Henan University of Science and Technology(2020-RSC02)Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).
