Preparation And Electromagnetic Shielding Mechanism Of Porous Composite Materials Based On Ti₃C₂T_x

With the rapid development of radar detection and wireless communication technology,the problem of electromagnetic interference has become increasingly serious.Therefore,the development of lightweight and high-performance anti-electromagnetic interference materials is essential to maintain communication safety and human health.Two-dimensional transition metal carbides（MXene）,represented by Ti₃C₂T_x,have become the most promising two-dimensional materials in the field of anti-electromagnetic interference due to their high electrical conductivity,large specific surface area,unique structure and abundant surface functional groups.However,the impedance mismatch caused by high electrical conductivity makes electromagnetic waves reflect strongly on its surface,thus seriously affecting its practical applications.In this paper,the relationship between impedance matching and dielectric loss is adjusted by constructing porous structure and doping SiC nanofibers to improve the anti-electromagnetic interference performance and investigate the corresponding influence mechanism.The main research results of this paper are summarized as follows:（1）MF/Ti₃C₂T_x/PEG porous composites（MTP）with three-dimensional open pore structure were successfully prepared by vacuum impregnation of Ti₃C₂T_x nanosheets and poly（vinyl alcohol）（PEG）loaded into MF using melamine foam（MF）as a template,respectively.The results show that the open porous structure of MTP can effectively reduce the reflection of electromagnetic waves caused by impedance mismatch,and the continuous conductive network constructed by Ti₃C₂T_x nanosheets inside MTP effiently dissipates the energy of incident electromagnetic waves,so that MTP exhibits electromagnetic shielding performance with absorption as the main mechanism.At the same time,the phase change material PEG gives MTP excellent thermal management performance,realizing the material design concept of integrating efficient thermal management and excellent dectromagnetic shielding paformance.（2）SiC nanofibers were prepared by electrostatic spinning and vacuum pyrolysis by selecting polycarbosilane（PCS）as the precursor.The SiC nanofibers and Ti₃C₂T_x nanosheets were bonded by electrostatic self-assembly using polydopamine（PDA）as the surface modifier,followed by the successful preparation of Ti₃C₂T_x/SiC foam（TSF）with oriented continuous pore structure by directional freeze-drying technique.The results showed that the dielectric constant of the composite could be effectively improved by adjusting the SiC nanofiber content to enhance its impedance matching performance.Secondly,the electron hopping model constructed between SiC nanofibers and Ti₃C₂T_x nanosheets,complex porous structure,and abundant interfaces and defects enable TSFs to possess various electromagnetic wave loss mechanisms such as conductivity loss,interfacial polarization,and dipole polarization.Therefore,through the synergistic effect between impedance matching and dielectric loss,TSF achieves high performance microwave absorption performance of thin,light,wide and strong.