Preparation And Electromagnetic Shielding Properties Of Ti₃C₂T_X/Konjac Glucomannan Composite Films

Since Ti₃C₂T_xwas first reported by Gogotsi et al.in 2011,it has been extensively studied.Because of its excellent conductivity,high surface area and easy modification,Ti₃C₂T_xhas broad application prospects in the field of electromagnetic shielding.However,Ti₃C₂T_xhas the disadvantages of poor mechanical property and easy oxidation,limiting its practical application.It has been reported that the combination of Ti₃C₂T_xwith polymers（such as polystyrene,polyvinylidene fluoride,polyurethane,etc.）can effectively improve the mechanical property and environmental stability of Ti₃C₂T_x,and expand its practical application.However,most synthetic polymers are difficult to degrade in the environment,causing serious pollution problems.Therefore,it is of great significance to prepare environment-friendly Ti₃C₂T_xbased electromagnetic shielding materials with high strength and high electromagnetic shielding properties.Inspired by the“brick-mortar”layered structure of mother of pearl and its excellent mechanical property,we use Ti₃C₂T_xnanosheets as"brick"and natural polymer konjac glucomannan（KGM）as well as deacetylated KGM（Da-KGM）as"mortar"to prepare Ti₃C₂T_x/KGM composite films and Ti₃C₂T_x/Da-KGM composite films with high strength and high electromagnetic shielding properties through simple vacuum-assisted filtration method.This paper mainly includes the following two aspects:（1）Ti₃C₂T_xnanosheets are prepared by in-situ etching of Ti₃Al C₂with lithium fluoride and hydrochloric acid,and then natural polymer KGM containing rich hydroxyl groups as"mortar"is introduced into Ti₃C₂T_xcontaining abundant surface polar groups as"brick".A series of layered Ti₃C₂T_x/KGM composite films are prepared via solution mixing and subsequent vacuum-assisted filtration method.The strong hydrogen bonding between KGM and Ti₃C₂T_xis beneficial to improve the mechanical property and stability of Ti₃C₂T_x.The tensile test results indicate that when the content of Ti₃C₂T_xis 40%,Ti₃C₂T_x/KGM composite film have the best mechanical properties.The tensile strength and elongation at break of Ti₃C₂T_X/KGM composite films are 144.5 MPa and 8.5%,respectively.In addition,the electromagnetic shielding efficiency（EMI SE）of this composite film is 23 d B at 8.2GHz,and the electromagnetic shielding efficiency is 99.49%.（2）In order to further prepare Ti₃C₂T_xbased composite film with high strength and high electromagnetic shielding properties,Deacetylated KGM（Da-KGM）is prepared by deacetylation of KGM with anhydrous sodium carbonate,and then Da-KGM is introduced into Ti₃C₂T_xsuspension,and the hydrogen bonding interaction is formed between Da-KGM and Ti₃C₂T_x.A series of hydrogen bonding crosslinked layered Ti₃C₂T_x/Da-KGM composite film are prepared.Finally,a series of double-crosslinked Ti₃C₂T_x/Da-KGM composite film are prepared by using borate ion as covalent bridge between Da-KGM and Ti₃C₂T_x.Due to the stronger interfacial interaction,the double-crosslinked layered Ti₃C₂T_x/Da-KGM composite film with hydrogen bonding and covalent bonding have good mechanical properties and excellent electromagnetic shielding properties.The tensile test results suggest that when the concentrations of anhydrous sodium carbonate and borate ion are 0.1 mol/L and 1.0 mg/m L,respectively,the double-crosslinked Ti₃C₂T_x/Da-KGM composite film have the best mechanical properties.Compared with the single crosslinked Ti₃C₂T_x/KGM film,the tensile strength and elongation at break of the double-crosslinked Ti₃C₂T_x/Da-KGM composite film are increased by 156%and 102%,respectively.In addition,the EMI SE of this composite film is 31 d B at 8.2 GHz,and the electromagnetic shielding efficiency can reach 99.92%.The results show that the dual-crosslinked Ti₃C₂T_x/Da-KGM film has not only good mechanical properties,but also high electromagnetic shielding properties,which is expected to be used in the field of flexible electronics.