Preparation And Performance Investigation Of Paper-based Electromagnetic Shielding Materials Based On MXene

With the development of science and technology,electromagnetic interference,electromagnetic information leakage and electromagnetic pollution are increasingly appearing,which not only affects the normal work and information security of equipment,but also harm people’s health.Therefore,reducing and shielding undesirable electromagnetic radiation has become an important subject in the field of science.At present,new conductive polymer composites（CPC）are gradually replacing traditional metal materials due to their excellent flexibility and electromagnetic interference shielding effectiveness（EMI SE）,leading the trend of electromagnetic shielding materials in the next era.Therefore,in this study,nano-silver flakes（AgNFs）were laid on the surface of the base paper as the electromagnetic wave reflection layer,and MXene（Ti₃CNT_X）loss layer was piled on top of this.Finally,the grid-like silver nanowires（AgNWs）were interwoven into MXene as the heat conduction and auxiliary reflection network,in which the high performance flexible electromagnetic shielding material was successfully prepared.On this basis,the EMI SE,mechanical properties,flame retardant performances and thermal conductivity of the composites were characterized and measured subsequently,which investigated and explained the role of each shielding component in the composites in detail and the corresponding shielding mechanism.The main conclusions are listed as follows:Monolayer MXene suspension was fabricated by mixed acid etching of LiF and HCl,and then MXene film was prepared by vacuum-assisted filtration.Through analyzing the power coefficients（SE_A,SE_Rand SE_T）of MXene film,the absorption loss of MXene film could reach26.1 d B.After annealing at 250℃for 6 h,the overall absorption loss of MXene film exhibited the best 34.8dB.With paper as the substrate,AgNFs was loaded on the surface of the base paper to obtain the AgNFs shielding layer.The conductivity and EMI SE of AgNFs were 500 s/cm and 48.97 d B,respectively.The MXene/AgNFs composite paper was fabricated by loading a layer of MXene electromagnetic wave loss layer on the surface of AgNFs shield layer.The EMI SE of which was further improved to 61.59 d B.Then,MXene@AgNWs/AgNFs（MAA）paper-based electromagnetic shielding material was fabricated by loading a layer of AgNWs network on the surface of AgNFs shielding layer and filling the AgNWs network with a layer of MXene.The EMI SE of which was further increased to 65.98 d B,and it exhibited excellent thermal conductivity,with a minimum surface temperature and temperature change rate of 27°C and8.0%,respectively,after bearing the LED lamp heating for 50 s.The MAA paper-based electromagnetic shielding material was fabricated by using paper as the flexible substrate,laminating AgNFs coating on the raw paper surface,constructing AgNWs network on its surface,and finally filling the MXene in the AgNWs network.The EMI SE,tensile strength and Young’s modulus could reach 70.96 d B,44.4 MPa and 0.6GPa,respectively.Meanwhile,the EMI SE and mechanical properties of the material were still as high as 51.69 d B,22.27 MPa and 0.92 GPa after being left for 24 h at a temperature of 100℃.In addition,the MAA laminated paper retained its original shape after 60 s of combustion.Moreover,even after immersion in inorganic and organic environments for 6 h,the material still exhibited EMI SE of51.01-62.48 d B.Using wallpaper as the base paper,the above method was adopted to prepare the electromagnetic shielding wallpaper.The physical indicators were complied with GB/T30129-2013 very well.The EMI SE of which could still reach 55.87 d B and 46.85 d B even at100℃and 100 RH%for 24 h,respectively.In summary,a flexible paper-based multifunctional composite material with efficient EMI SE was successfully fabricated in this study.While possessing excellent EMI SE,the material also exhibited good thermal conductivity,flame retardancy,mechanical properties and stability,showing the excellent potential for application in advanced flexible electromagnetic shielding products.