Preparation Of Ultrastrong And Highly Conductive Mxene-based Film For Electromagnetic Interference Shielding

The rapid development of science and technology in the information age,the problem of electromagnetic pollution is severe.The high-performance electromagnetic interference(EMI)shielding materials are particularly important.Two-dimensional transition metal carbides/nitrides(MXene)with remarkable metallic conductivity are considered as ideal candidates for high-performance EMI shielding materials.The weak interfacial interaction between MXene nanosheets leads to poor mechanical properties which hinders its practical application.To solving the problem of improving the mechanical properties of MXene-based films while the conductivity drops sharply,the MXene-based film imitated the structure of nacre.The MXene-based films have excellent mechanical properties,high conductivity,and remarkable electromagnetic shielding performance.The main research contents include:(1)By introducing cellulose nanocrystals(CNC)with one-dimensional rod-like into the MXene,the hydroxyl groups on the surface of the CNC and MXene surface groups can form the hydrogen bond interactions.At the same time,the interlocking structure combined by one-dimensional and two-dimensional materials can improve the mechanical properties.With 40 wt%of CNC added,the tensile strength reached to 57 MPa,the conductivity is 13400 S m-1 and electromagnetic interference shielding efficiency(EMI SE)is 36.1 dB with the thickness of 8?m.(2)Increase the strength of MXene film by enhancing the interface adhesion between MXene nanosheets adjacent to multivalent aluminum ions.The tensile strength of the MXene film reached 83.2 MPa and its conductivity is retained at 265600 S m-1.The strong and highly conductive MXene film with a small thickness of 39?m exhibits the highest EMI shielding performance over 80 dB in the X-band.(3)By adding two-dimensional graphite oxide(GO)to the MXene and then removing some of the polar functional groups on the GO surface by hydroiodic acid(HI)or heat treatment at 300?.This can adjust the film wettability and improve the stability of the material.When the GO content is 50 wt%,the tensile strength of the HI-reduced film reached 129 MPa,the electrical conductivity is 76900 S m-1,and EMI SE is 42 dB with the thickness of 8?m.