Scalable Preparation And Electromagnetic Shielding Properties Of MXene-Based Films With High Strength

The vigorous development of wireless communication technology and electronic devices has not only brought great convenience to people’s daily life but also given rise to serious electromagnetic pollution.Electromagnetic radiation not only affects the normal work of electronic and electrical equipment,causing the loss and leakage of computer information but also is harmful to human health.Using electromagnetic interference（EMI）shielding materials to suppress or attenuate electromagnetic pollution is an effective method.Two-dimensional transition metal carbides and/or nitrides（MXene）with ultra-high metal conductivity,especially Ti₃C₂T_X MXene,are uniquely suited to achieve high-performance EMI shielding materials,but the poor mechanical properties and environmental stabilities limit their practical applications.Meanwhile,conventional procedures of constructing MXene films are just suitable for laboratory research and do not meet the needs of industrial applications that require high throughput.Therefore,improving preparation methods and designing hybridized structures based on MXene nanosheet layers are of importance to broaden their applications.In this paper,the preparation procedure of Ti₃C₂T_X MXene nanosheets was improved firstly to obtain high-quality large-size nanosheets.Then,the composite films of MXene and graphene oxide（GO）were fabricated by the scraping method to investigate their mechanical and electromagnetic shielding properties.Finally,polyvinyl alcohol（PVA）was introduced into the composite films and reduced with hydroiodic acid to obtain the composite films of MXene,reduced graphene oxide（rGO）,and PVA.The mechanical properties,electromagnetic shielding properties,and environmental stabilities were investigated.The specific research of this paper is as follows:1.High-quality MXene nanosheets were obtained by screening the particle size of the precursor Ti₃Al C₂ MAX phase,which was etched and exfoliated by a modified minimally intensive layer delamination method without ultrasonic process.Subsequently,scalable prepared compact nacre-mimetic MXene films were obtained by the blade-coating method.The MXene nanosheets obtained by this process are around 10μm in size,and the tensile strength of the obtained films is up to 90±3 MPa,and the electromagnetic shielding effectiveness（EMI SE）of the MXene films is up to59.09 d B at a thickness of only 8μm.2.The film-forming performance is improved by introducing a larger size of GO into MXene slurry,and strong hydrogen bonds are formed between the two to improve the tensile strength of composite films.The tensile strength of the modified MXene film reaches 121±10 MPa at 15wt%GO content and the electrical conductivity is maintained at 1774.56 S cm^-1.This high-strength and high conducting MXene based film reach 49.02 d B EMI SE at 8μm thickness.3.By introducing PVA as a locking agent in the binary mixture of MXene,GO,and reducing GO with hydroiodic acid to reduced graphene oxide（rGO）,not only the mechanical properties of the film can be effectively enhanced,but also the environmental stability of the composite film can be greatly improved.When the mass ratio of MXene,rGO,and PVA is 85:15:25,the final composite film conductivity decreases to 32.07 S cm^-1,but the tensile strength and toughness of the film could reach238±11 MPa and 1.72±0.11 MJ m^-3,respectively.Meanwhile,the film’s EMI SE can reach 41.35 d B at 12μm and SSE/t can be maintained at 20204 d B cm² g^-1.In addition,the film can maintain relatively stable EMI shielding performance after treatment in harsh environments such as ultrasound（360 W,10 min）,high temperature（100°C,5 h）,liquid nitrogen（-196°C,1 h）,and acid solution（HCl,1 M,2 h）,and the mechanical strength can be maintained at more than 90%.