Preparation Of Ti₃C₂T_x Composites And Study On Their Electromagnetic Wave Absorption And Shielding Properties

The rapid development of wireless communication technology and the excessive use of electronic devices have caused serious electromagnetic polluti on,which is not only harmful to human health,but also affects the accurate of sophisticated electronic devices and even endangers national security.Therefore,in order to effectively prevent the unnecessary diffusion of electromagnetic waves,the electromagnetic wave absorption and interference shielding materials have been paid more and more attention.Ti3C2 Tx MXene is the most widely used and studied in the MXenes family,due to its advantages of simple preparation,clear structure and stable performance.In this paper,Ti3C2 Tx MXene is used as the functional material to prepare different Ti3C2 Tx composites,which have excellent performance in electromagnetic interference shielding and absorption.The few-layers Ti₃C₂T_x?named d-Ti3C2 Tx in the text?with delaminated structure is obtained by using in situ HF etching,which has 1-3 layers.The aramid nanofibers?ANFs?,is fabricated by etching kevlar fibers.Then,d-Ti3C2 Tx and ANFs mix together to obtain the ultrathin d-Ti₃C₂T_x/ANFs composite films.The composite films not only have excllent electromagnetic interference shielding performance,but also high mechanical strength,ultrathin and good toughness properties.Due to the poor tensile strength?16 MPa?of the pure d-Ti3C2 Tx film,high strength ANFs are used to enhance the few-layers d-Ti3C2 Tx films,and then the self-supporting d-Ti₃C₂T_x/ANFs composite films are obtained.The ultimate tensile strength and strain of the composite films reach upto 116.71 MPa and 2.64 %,respectively.At the same time,the electromagnetic interference shielding performance of the composite films could upto 34.71 d B?with the thickness of 12 ?m?and the maximum SSE/t is 21971.37 d B cm2 g-1.In addition,the composite films also have excellent toughness,and their electromagnetic interference shielding performance do not decline after 1000 times of bending deformation.In order to obtain superior microwave absorbing material,Ti₃C₂T_x/PANI composite with sandwich structure is prepared by in-situ polymerization of polyaniline?PANI?between interlayers and on the surface of accordion structure Ti3C2 Tx.Ti₃C₂T_x/PANI has excellent electromagnetic absorption properties due to the synergistic effect between Ti3C2 Tx and PANI,and the alternating structure of the composite.Under condition of appropriate PANI content and the paraffin matrix,the maximum reflection loss of Ti₃C₂T_x/PANI composite is upto-56.30 d B with the sample thickness only 1.8 mm when the mass fraction of Ti₃C₂T_x/PANI composite material in wax matrix is 50 wt%,demonstrating that exceeding 99.999% electromagnetic wave is absorbed.The study also finds that by adjusting the thickness of the sample to a range of 1.5?2.6 mm,the effective absorption bandwidth of the Ti₃C₂T_x/PANI composite could cover the whole X-band and Ku-band.In addition,Ti₃C₂T_x/PANI/ANFs composite film is prepared at the optimal ratio between Ti3C2 Tx and PANI,and its electromagnetic interference shielding performance is better than d-Ti₃C₂T_x/ANFs composite film with the same mass fraction of d-Ti3C2 Tx.Subsequently,in order to obtain light electromagnetic interference shielding materials,hollow fibers and Ti₃C₂T_x/hollow composite fibers are prepared.And their electromagnetic interference shielding properties are also studied.The preparation technology of PMMA/PAN composite fibers are studied firstly,and the sea-island and skin-core fibers are prepared.After that,magnetic PAN-Fe₃O₄ hollow fiber is prepared by composite spinning technology,and then via chemical vapor deposition?CVD?,we obtain the magnetic hollow carbon fiber grown with carbon nanotubes on the inner and outer surfaces.After the growth of carbon nanotubes at high temperature,the Fe₃O₄ converts into Fe3 C.Due to the synergistic effect of CNTs coatings,Fe3 C and one-dimensional?1D?hollow structures,the composite fibers?CHFs?with excellent electromagnetic interference shielding and lightweight properties are obtained.The electromagnetic interference shielding effectiveness of CHFs is up to 80.00 d B,and ranged between 73.10 and 80.00 d B in the whole X-band.Attributed to the hollow structure,the density of the composite fiber is only ? 1.0 g cm-3.In addition,d-Ti3C2 Tx is coated on the surface of CHFs by simple mixing method to obtain Ti₃C₂T_x/CHFs composite fibers.And the electromagnetic interference shielding performance of Ti₃C₂T_x/CHFs composite fibers is also investigated.In this paper,using Ti3C2 Tx as functional material,gradually optimizing the performance of the materials,different Ti3C2 Tx composites with different compositions,structures and morphologies are prepared.And those composite materials have excellent electromagnetic wave absorption or interference shielding properties.Those composites could be used for varieties of applications,such as shielding tents,absorbing coatings,fiber shielding,wearable clothing and so on.This research provides a novle idea and reference for the future preparation of MXene composite materials.