Preparation And Properties Of Reinforced And Toughened Ti₃C₂T_x Electromagnetic Shielding Composite Films

Ti₃C₂T_x is a new class of 2D layered transition metal carbides or carbides,which are widely used as electromagnetic shielding materials.However,due to poor mechanical properties and brittleness,it is difficult to withstand a certain degree of machining deformation,which limits the expansion of its application field.Therefore,in this paper,nano-cellulose whiskers（CNC）were selected as the reinforcing phase and water-based polyurethane（WPU）as the toughening phase to prepare toughened and reinforced Ti₃C₂T_x electromagnetic shielding composite film to improve its machinability and further broaden its application in flexible wearable devices and other fields.The main research contents are as follows:（1）Ti₃C₂T_x nanosheets with few layers and large area were prepared by in-situ hydrofluoric acid etching.The Ti₃C₂T_x thin films were prepared by simple vacuum filtration have high electrical conductivity and high shielding efficiency of electromagnetic interference.In addition,CNC with a diameter of 20-50 nm and a length of 200-400 nm were prepared by acid hydrolysis of waste corrugated paper.（2）Ti₃C₂T_x/CNC composite films with different mass ratios were prepared by vacuum filtration method.The results show that the prepared Ti₃C₂T_x/CNC（14:3）composite film（12μm thick）has a screen value of 62 dB,an electrical conductivity of 3125 S/cm,and an elongation at break of 1.6%.Ti₃C₂T_x/WPU composite films with different mass ratios were prepared by vacuum filtration method.The results show that the shielding value of the prepared Ti₃C₂T_x/WPU（14:8）composite film（20 μm thick）is 48.7 dB,the electrical conductivity is 499.96 S/cm,and the elongation at break is 2%.（3）The double-layer Ti₃C₂T_x/CNC/WPU composite films were prepared by vacuum filtration method.The results show that the addition of CNC in the preparation process of Ti₃C₂T_x/WPU composite film can not only improve the shielding performance of the original composite film,but also improve its mechanical properties.Ti₃C₂T_x/CNC/WPU（14:4.5:8）composite film（thickness 35 μm）has a screen value of 54.2 dB,a conductivity of 513.26 S/cm,and an elongation at break of 2.9%.（4）The sandwich structures Ti₃C₂T_x/WPU and Ti₃C₂T_x/CNC/WPU were prepared by optimizing the structure of the double-layer composite films.The results show that the screen covering value of Ti₃C₂T_x/WPU（14:8）composite film（20 μm thick）is 52.6 dB,and that of Ti₃C₂T_x/CNC/WPU（14:4.5:8）composite film（35 μm thick）is 56.5 dB.Compared with the double-layer composite film,the sandwich structure composite film can improve the shielding effect of the composite material better on the basis of maintaining good mechanical properties.In this study,based on Ti₃C₂T_x material modification,the composite film prepared has good electromagnetic interference shielding efficiency,and has excellent machinability and flexibility,which has a broad application prospect in the electromagnetic shielding packaging and anti-static packaging of precision instruments.