Bio-Inspired Construction Of Layered MXene/ANF Nanocomposites And Study Of Its Properties

With the vigorous development of information technology and intelligence in modern society,small electronic devices,while providing convenience,also have an irreversible impact on human production and life.For example,the rapidly transmission of information generates interference electromagnetic waves and heat,which can affect the regular running of equipment and the healthy survival of human beings.In addition,single functional materials are no longer able to fulfill the miniaturized space of electronic devices.Therefore,MXene,as a metallic two-dimensional material,has metallic properties such as high electrical and thermal conductivity,as well as light weight and corrosion resistance,which endows it with excellent electromagnetic shielding,Joule heat and so on,and it has become a potential new star to solve the above problems.However,the self-assembled pure MXene films have poor mechanical properties due to the weak intermolecular forces between the nanosheets,which significantly restricts their application in production practice.To address the issues of material functionality and mechanical properties,this work proposes the concept of learning from nature,imitating the shell structure and constructing interfacial interaction forces,and successfully prepares MXene/aramid nanofibers（ANF）nanocomposites,which achieve the perfect unification of function and mechanics.The composite not only has the mechanical properties of light weight,high strength and flexibility,but also has excellent electromagnetic interference shielding,Joule heating and thermal management.The details of the study are as follows:（1）The construction of high-strength and high-performance MXene/ANF composites.In this work,inspired by the microstructure and interfacial interactions of natural abalone shells,MXene/ANF nanocomposite paper was prepared on large scale by blade-coating process plus sol-gel conversion technique using the synthesized MXene/DMSO solution and ANF/DMSO solution as raw materials.This as-synthesized composite papers possess exceptional tensile strength（198.80±5.35 MPa）,large strain（15.30±1.01%）and excellent flexibility（folded into various models without fracture）.The extraordinary mechanical properties are mainly ascribed to the synergistic effect of the bio-inspired constructed layered structure,the fibrous framework structure,and the hydrogen bondings between MXene and ANF.More importantly,the papers with extensive continuous conductive paths formed by MXene nanosheets present a high EMI shielding effectiveness of 13188.2 d B cm² g^-1 in the frequency range of 8.2-12.4 GHz.More interestingly,after the application of a voltage of 4.0 V for 10 s,the surface temperature of the composite paper was as high as146.1°C,presenting fast thermal response,low driving voltage and high Joule heating temperature.Thus,the prepared composite paper exhibited excellent Joule thermal properties.In conclusion,the above results indicate that the layered MXene/ANF nanocomposite papers were successfully prepared on a large scale in this experiment,which provides a feasible strategy for their applications in electromagnetic shielding and thermal management.（2）The construction of a functionally integrated MXene/ANF composite.In this work,large-size,highly conductive MXene（Al-Ti₃C₂T_x）nanosheets were fabricated using concentrated dual-acid etching（concentrated HF and HCl）and Li⁺intercalation processes,of which the Al-Ti₃C₂T_x/ANF nanocomposite films with hierarchically ordered layered structures were compounded with ANF by vacuum-assisted filtration（VAF）method.The advantage of the layered 40 wt%Al-Ti₃C₂T_x/ANF film with a thickness of 10μm lies in that it possesses excellent mechanical properties(strength:200.79±1.32 MPa,strain-to-failure:8.05±0.65%,toughness:9.96±0.84 MJ m^-3),superior EMI shielding effectiveness of 15264 d B cm² g^-1,high electrothermal conversion temperature up to≈120.7°C with rapid response time of 4 s.Furthermore,the nanocomposite film also boasts superhydrophobic property（contact angle>150°）as well as the flame retardancy.The large-sized Al-Ti₃C₂T_x nanosheets constructing all-in-one multifunctional film provides an ideal candidate material for EMI shielding and thermal management under complex environmental condition.