High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the norma...High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.展开更多
The conductive nano-sized zinc particles were embedded in an insulating amorphous silica matrix,and the hybrid films were obtained by a sol-gel method.The stable hybrid sol solution was prepared by hydrolysis and cond...The conductive nano-sized zinc particles were embedded in an insulating amorphous silica matrix,and the hybrid films were obtained by a sol-gel method.The stable hybrid sol solution was prepared by hydrolysis and condensation of Methyltrimethoxysilane （MTMS） with a one-step acidic catalyst process.Hybrid films were dip-coated on silicon wafer and cured at 120℃ for 60minutes.The structural characterization of hybrid films were investigated by means of attenuated total reflection infrared （ATR-IR） spectroscopy and X-ray diffraction （XRD）.The electrical properties of the films were examined with four-point probe.Hybrid films showed to be relatively dense,uniform and defect free.The conductivity of hybrid films was varied with the different contents of zinc nanoparticles and the thickness of the film.It was observed that there was the percolation threshold for the film＇s electrical properties.展开更多
Highly conductive polymer composites(CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference(EMI) shielding materials,which can be used for the electromagne...Highly conductive polymer composites(CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference(EMI) shielding materials,which can be used for the electromagnetic interference protection of flexible electronic devices.It is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive networks.In this paper,a novel silver-plated polylactide short fiber(Ag@PL ASF,AAF) was fabricated and was integrated with carbon nanotubes(CNT) to construct a multi-scale conductive network in polydimethylsiloxane(PDMS) matrix.The multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m-1and ultra-strong EMI shielding effectiveness(EMI SE) of up to 113 dB,containing only 5.0 vol% of AAF and 3.0 vol% of CNT(11.1wt% conductive filler content).Due to its excellent flexibility,the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy(60℃ for 7 days) and 10,000 bending-releasing cycles.This strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace,environment and sensitive circuits against radiation for flexible electronic devices.展开更多
As portable and wearable electronic devices are rapidly developing,there is an urgent need for flexible and robust thermally conductive electromagnetic interference shielding materials to address the associated electr...As portable and wearable electronic devices are rapidly developing,there is an urgent need for flexible and robust thermally conductive electromagnetic interference shielding materials to address the associated electromagnetic pollution and overheating issues.Herein,multifunctional poly(p-phenyl-2,6-phenylene bisoxazole)nanofiber/boron nitride nanosheet/Ti_(3)C_(2)T_(x)MXene nanosheet(PBO/BN/MXene)composite papers are prepared by a gel microparticle-mediated ordered assembly process with the aid of vacuum-assisted filtration.Nacre-like“brick and mortar”structure,segregated structure and sandwich structure are integrated into the composite paper,so that efficient thermally and electrically conductive networks have been established.When the BN and MXene contents are 29.2 wt%and 41.7 wt%,the 13μm thick composite paper exhibits an EMI shielding performance of 31.8 dB and a thermal conductivity of 26.1 W/mK,markedly superior to those of the control samples without the ordered structures.Meanwhile,because of the unique architecture and inherent advantages of the building blocks,the composite paper exhibits extremely low coefficient of thermal expansion(~1.43 ppm/K),excellent mechanical properties,and outstanding thermal stability and flame retardance,making it highly advantageous for practical applications in electronic devices.This work offers a promising approach for fabricating high-performance multifunctional composites by constructing efficient filler networks.展开更多
To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompat...To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompatibility. Herein, we reported a polypyrrole-coated zein/epoxy(PPy/ZE) ultrafine fiber mat which was inherently biodegradable and skin-friendly. In addition, it could maintain its ultrafine fibrous structure after coating, which could provide the mat with mechanical compliance, high porosity, and a large specific area for high EMI shielding. With the assistance of the epoxide cross-linking, the breaking stresses of the PPy/ZE fiber mats could achieve 3.3 MPa and 1.4 MPa and the strains were 40.1% and 83.0% in dry and wet states, respectively, which met the needs of various wearable electronic devices. Along with the extension in the PPy treatment duration, more PPy was loaded on the fiber surfaces, which formed more integrated and conductive paths to generate increasing conductivities up to 401.76 S·m^(-1). Moreover, the EMI shielding performance was raised to 26.84 dB. The biobased mats provide a green and efficient choice for EMI shielding materials, which may be a promising strategy to address EMI problems in multiple fields.展开更多
Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious e...Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious electromagnetic leakage at the conjunctions between the conductive tapes and target objects.Adding conductive fillers is a traditional method for highly conductive adhesive tapes.However,the content of conductive fillers is needed to reach the percolation threshold,which is usually as high as tens of percent.High-content fillers result in significant loss of adhesive property and high fabrication cost.Herein,we introduce a rational architecture of conductive microsphere monolayer(CMM)in the PSA layer.The CMM connects the top and bottom surfaces of the PSA layer and improves its conductivity in the z-direction.Importantly,low contents of conductive microspheres(≤5%(mass fraction,w))can achieve the target of conductivity improvement,but not result in the serious loss of the adhesive property.Therefore,the strategy of CMMs can balance the tradeoff between the conductivity and the adhesive property of conductive PSA tapes.Finally,we demonstrate the superior EMI shielding performance of as-made conductive adhesive tapes,indicating their potential applications as the advanced EMI shielding materials in the electronic packaging.展开更多
Carbon materials engineered electrically conductive cement concrete(ECCC)is typically prepared by directly adding carbon-based conductive filler into the cement matrix and then mixing cement with aggregates.With such ...Carbon materials engineered electrically conductive cement concrete(ECCC)is typically prepared by directly adding carbon-based conductive filler into the cement matrix and then mixing cement with aggregates.With such a strategy,ECCC possesses a high conductivity and strain/stress sensitivity and thus can be used for snow and ice melting,ohmic heating,cathodic protection system,electromagnetic shielding,structural health monitoring,and traffic detection.This paper aims to provide a systematic review on the development and applications of ECCC,especially the progress made in the past decade(from 2012 to 2022).The composition and manufacture of ECCC are first introduced.Then,the electrical performance of ECCC and its potential applications are reviewed.Finally,the remaining challenges for future work are discussed.展开更多
The Ti_(3)C_(2)T_(x)MXene is thought to be a promising candidate for next-generation electromagnetic interference(EMI) shielding materials.However,its broadband shielding capability and thermal conduction performance ...The Ti_(3)C_(2)T_(x)MXene is thought to be a promising candidate for next-generation electromagnetic interference(EMI) shielding materials.However,its broadband shielding capability and thermal conduction performance are insufficient to meet the growing demands.Herein,we reported a layer-by-layer composite film composed of Ti_(3)C_(2)T_(x)MXene,multi-walled carbon nanotubes(MWCNTs),and Fe_(3)O_(4)nanoparticles.Benefitting from the architecture and the synergistic effect of components,the obtained composite film exhibited high comprehensive performance.Specifically,the introduction of Fe_(3)O_(4)magnetic nanoparticles effectively reduced the impedance mismatch between the composite film and air and enhanced the magnetic loss of the composite film.The layered structure prolonged the transmission path of electromagnetic waves inside the composite film and constructed a rich conductive network,causing interfacial polarization and ohmic loss.The results indicated that the composite film(52 μm) delivered a high EMI shielding effectiveness of 49 dB in the frequency range from X-band to Ku-band.Furthermore,the MWCNTs layers in the composite films provided numerous heat transfer channels,reducing phonon scattering during heat transfer and resulting in a maximum thermal conductivity of 8.241 W/(m K).展开更多
研究了以碳纳米管（CNTs）和碳纤维（CF）作为复合导电剂的导电纸。通过高速剪切的方法将分散好的导电剂和纸浆纤维素在水溶液中复合,经真空抽滤法沉积得到导电纸。纤维状的导电剂与纸浆纤维搭建成三维导电网络,表现出了良好的柔韧性、...研究了以碳纳米管（CNTs）和碳纤维（CF）作为复合导电剂的导电纸。通过高速剪切的方法将分散好的导电剂和纸浆纤维素在水溶液中复合,经真空抽滤法沉积得到导电纸。纤维状的导电剂与纸浆纤维搭建成三维导电网络,表现出了良好的柔韧性、导电性和电磁屏蔽性能。采用扫描电子显微镜、四探针电阻仪、矢量网络分析仪对其进行表征。研究表明,当碳纤维和碳纳米管以1∶1比例添加作为复合导电剂时,碳纤维-碳纳米管复合纸的导电性能和电磁屏蔽性能较碳纤维或碳纳米管单一导电剂提高明显。复合导电纸的电导率达到280.1 S/m,在175-1600MHz频段电磁屏蔽效能达到37-44 d B,较碳纤维纸提高2 d B,较碳纳米管纸提高10 d B。展开更多
基金Foundation of National Natural Science Foundation of China,Grant/Award Number:51903145Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China,Grant/Award Number:2019JC-11Wang L.would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,Grant/Award Number:CX202053。
文摘High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.
文摘The conductive nano-sized zinc particles were embedded in an insulating amorphous silica matrix,and the hybrid films were obtained by a sol-gel method.The stable hybrid sol solution was prepared by hydrolysis and condensation of Methyltrimethoxysilane （MTMS） with a one-step acidic catalyst process.Hybrid films were dip-coated on silicon wafer and cured at 120℃ for 60minutes.The structural characterization of hybrid films were investigated by means of attenuated total reflection infrared （ATR-IR） spectroscopy and X-ray diffraction （XRD）.The electrical properties of the films were examined with four-point probe.Hybrid films showed to be relatively dense,uniform and defect free.The conductivity of hybrid films was varied with the different contents of zinc nanoparticles and the thickness of the film.It was observed that there was the percolation threshold for the film＇s electrical properties.
基金supported by the National Natural Science Foundation of China(Nos.51973142,52033005,52003169).
文摘Highly conductive polymer composites(CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference(EMI) shielding materials,which can be used for the electromagnetic interference protection of flexible electronic devices.It is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive networks.In this paper,a novel silver-plated polylactide short fiber(Ag@PL ASF,AAF) was fabricated and was integrated with carbon nanotubes(CNT) to construct a multi-scale conductive network in polydimethylsiloxane(PDMS) matrix.The multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m-1and ultra-strong EMI shielding effectiveness(EMI SE) of up to 113 dB,containing only 5.0 vol% of AAF and 3.0 vol% of CNT(11.1wt% conductive filler content).Due to its excellent flexibility,the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy(60℃ for 7 days) and 10,000 bending-releasing cycles.This strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace,environment and sensitive circuits against radiation for flexible electronic devices.
基金supported by the National Natural Science Foundation of China(51733008)the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH032).
文摘As portable and wearable electronic devices are rapidly developing,there is an urgent need for flexible and robust thermally conductive electromagnetic interference shielding materials to address the associated electromagnetic pollution and overheating issues.Herein,multifunctional poly(p-phenyl-2,6-phenylene bisoxazole)nanofiber/boron nitride nanosheet/Ti_(3)C_(2)T_(x)MXene nanosheet(PBO/BN/MXene)composite papers are prepared by a gel microparticle-mediated ordered assembly process with the aid of vacuum-assisted filtration.Nacre-like“brick and mortar”structure,segregated structure and sandwich structure are integrated into the composite paper,so that efficient thermally and electrically conductive networks have been established.When the BN and MXene contents are 29.2 wt%and 41.7 wt%,the 13μm thick composite paper exhibits an EMI shielding performance of 31.8 dB and a thermal conductivity of 26.1 W/mK,markedly superior to those of the control samples without the ordered structures.Meanwhile,because of the unique architecture and inherent advantages of the building blocks,the composite paper exhibits extremely low coefficient of thermal expansion(~1.43 ppm/K),excellent mechanical properties,and outstanding thermal stability and flame retardance,making it highly advantageous for practical applications in electronic devices.This work offers a promising approach for fabricating high-performance multifunctional composites by constructing efficient filler networks.
基金Fundamental Research Funds for the Central Universities,China(No. 2232022D-13)Fundamental Research Funds of Shanghai Collaborative Innovation Center of High Performance Fibers and Composites (Province-M inistry Joint),China(No. X12812101/015)。
文摘To reduce the environmental pollution and meet the needs for wearable electronic devices, new requirements for electromagnetic interference(EMI) shielding materials include flexibility, biodegradability, and biocompatibility. Herein, we reported a polypyrrole-coated zein/epoxy(PPy/ZE) ultrafine fiber mat which was inherently biodegradable and skin-friendly. In addition, it could maintain its ultrafine fibrous structure after coating, which could provide the mat with mechanical compliance, high porosity, and a large specific area for high EMI shielding. With the assistance of the epoxide cross-linking, the breaking stresses of the PPy/ZE fiber mats could achieve 3.3 MPa and 1.4 MPa and the strains were 40.1% and 83.0% in dry and wet states, respectively, which met the needs of various wearable electronic devices. Along with the extension in the PPy treatment duration, more PPy was loaded on the fiber surfaces, which formed more integrated and conductive paths to generate increasing conductivities up to 401.76 S·m^(-1). Moreover, the EMI shielding performance was raised to 26.84 dB. The biobased mats provide a green and efficient choice for EMI shielding materials, which may be a promising strategy to address EMI problems in multiple fields.
基金the financial support from the National Natural Science Foundation of China(Grant No.62074154)Shenzhen Science and Technology Program(Grant Nos.JSGG20210802153000002,JCYJ20210324102208023).
文摘Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious electromagnetic leakage at the conjunctions between the conductive tapes and target objects.Adding conductive fillers is a traditional method for highly conductive adhesive tapes.However,the content of conductive fillers is needed to reach the percolation threshold,which is usually as high as tens of percent.High-content fillers result in significant loss of adhesive property and high fabrication cost.Herein,we introduce a rational architecture of conductive microsphere monolayer(CMM)in the PSA layer.The CMM connects the top and bottom surfaces of the PSA layer and improves its conductivity in the z-direction.Importantly,low contents of conductive microspheres(≤5%(mass fraction,w))can achieve the target of conductivity improvement,but not result in the serious loss of the adhesive property.Therefore,the strategy of CMMs can balance the tradeoff between the conductivity and the adhesive property of conductive PSA tapes.Finally,we demonstrate the superior EMI shielding performance of as-made conductive adhesive tapes,indicating their potential applications as the advanced EMI shielding materials in the electronic packaging.
基金The authors would like to acknowledge the financial support by the National Natural Science Foundation of China(Grant Nos.52278164 and 51878224)the National Key Research and Development Program of China(Gant No.2022YFB3706503).
文摘Carbon materials engineered electrically conductive cement concrete(ECCC)is typically prepared by directly adding carbon-based conductive filler into the cement matrix and then mixing cement with aggregates.With such a strategy,ECCC possesses a high conductivity and strain/stress sensitivity and thus can be used for snow and ice melting,ohmic heating,cathodic protection system,electromagnetic shielding,structural health monitoring,and traffic detection.This paper aims to provide a systematic review on the development and applications of ECCC,especially the progress made in the past decade(from 2012 to 2022).The composition and manufacture of ECCC are first introduced.Then,the electrical performance of ECCC and its potential applications are reviewed.Finally,the remaining challenges for future work are discussed.
基金financially supported by the National Natural Science Foundation of China (No.52171191)the project funded by the China Postdoctoral Science Foundation (No.2020T130525)+4 种基金the Shaanxi Province Postdoctoral Science Foundation (No.2018BSHEDZZ113)supported by the ISF-NSFC Joint Research Program (No.51961145305)the Shaanxi Key Program for International Science and Technology Cooperation Projects (No.2021KWZ-12)Open Fund from Henan University of Science and Technologythe Youth Innovation Team of Shaanxi Universities。
文摘The Ti_(3)C_(2)T_(x)MXene is thought to be a promising candidate for next-generation electromagnetic interference(EMI) shielding materials.However,its broadband shielding capability and thermal conduction performance are insufficient to meet the growing demands.Herein,we reported a layer-by-layer composite film composed of Ti_(3)C_(2)T_(x)MXene,multi-walled carbon nanotubes(MWCNTs),and Fe_(3)O_(4)nanoparticles.Benefitting from the architecture and the synergistic effect of components,the obtained composite film exhibited high comprehensive performance.Specifically,the introduction of Fe_(3)O_(4)magnetic nanoparticles effectively reduced the impedance mismatch between the composite film and air and enhanced the magnetic loss of the composite film.The layered structure prolonged the transmission path of electromagnetic waves inside the composite film and constructed a rich conductive network,causing interfacial polarization and ohmic loss.The results indicated that the composite film(52 μm) delivered a high EMI shielding effectiveness of 49 dB in the frequency range from X-band to Ku-band.Furthermore,the MWCNTs layers in the composite films provided numerous heat transfer channels,reducing phonon scattering during heat transfer and resulting in a maximum thermal conductivity of 8.241 W/(m K).
文摘研究了以碳纳米管（CNTs）和碳纤维（CF）作为复合导电剂的导电纸。通过高速剪切的方法将分散好的导电剂和纸浆纤维素在水溶液中复合,经真空抽滤法沉积得到导电纸。纤维状的导电剂与纸浆纤维搭建成三维导电网络,表现出了良好的柔韧性、导电性和电磁屏蔽性能。采用扫描电子显微镜、四探针电阻仪、矢量网络分析仪对其进行表征。研究表明,当碳纤维和碳纳米管以1∶1比例添加作为复合导电剂时,碳纤维-碳纳米管复合纸的导电性能和电磁屏蔽性能较碳纤维或碳纳米管单一导电剂提高明显。复合导电纸的电导率达到280.1 S/m,在175-1600MHz频段电磁屏蔽效能达到37-44 d B,较碳纤维纸提高2 d B,较碳纳米管纸提高10 d B。
