| With the rapid popularization of global electronic equipment and the continuous improvement of related electronic equipment power,the electromagnetic wave pollution is rising sharply,which affects human health and normal life.In order to improve the ability of anti electromagnetic pollution of electronic equipment,it is necessary to design a material with certain electromagnetic shielding performance to protect the normal operation of the equipment.However,the traditional electromagnetic shielding materials have the problems of complex process,high cost and low preparation efficiency.At present,optimizing preparation methods,improving mechanical properties,regulating microstructure and exploring other properties have become the research and development direction of electromagnetic shielding materials.Cellulose,as the most resource-rich polymer material in the world,has excellent mechanical strength,good flexibility and other characteristics,among which nanocellulose has a one-dimensional nanostructure,high aspect ratio,plays an important role in the field of electromagnetic shielding.In order to solve the problems of high density and poor toughness of traditional electromagnetic shielding materials,this paper constructed cellulose nanofiber(CNF)/Mxene ternary composites to explore its application in electromagnetic shielding field and expand its application field.In order to solve the above problems,cellulose,as the most abundant polymer material in the world,plays an important role in the field of new electromagnetic shielding materials because of its excellent mechanical strength and flexibility.Aiming at the problems of high density and poor toughness of traditional electromagnetic shielding materials,new ideas are carried out and applied to different environments to explore other multifunctional research based on electromagnetic shielding performance.Firstly,MXene reduced silver nanoparticles and nanocellulose composite films with a brick-like structure were prepared by vacuum filtration method.It was found that the addition of nanocellulose fiber(CNF)enhanced the hydrogen bonding force,resulting in good electromagnetic shielding performance(50.7 d B)and mechanical properties(32.1 MPa).And the composite film has excellent conductivity(588.2 SM-1),which provides a new idea for the high value utilization of green biomass materials.In addition,because the silver nanoparticles reduced by MXene are dispersed in the"brick and tile"structure,this special structure not only enhances the winding and hydrogen bonding forces between the composites,but also further enhances the electromagnetic shielding loss,which will have a promising application in the field of electromagnetic shielding.Secondly,the unique shell-like CNF/MXene/MMT composite films were prepared.Compared with the traditional pure mxene film,the composite film has excellent electromagnetic shielding performance(44 d B),thermal insulation performance and mechanical properties(127 MPa).Both nano cellulose and MMT have low thermal conductivity,so the composite film has certain photothermal properties.The composite film has potential applications in heat insulation,electromagnetic shielding and other fields,which lays a foundation for the development of multifunctional electromagnetic shielding composite materials.Finally,lightweight and flexible CNF/MXene aerogels were prepared by freeze-drying.Aerogels were obtained after MXene and nanofibers were freeze-dried to obtain block aerogels and then coated with silicone.The three-dimensional network framework can further absorb the electromagnetic pollution,and the electromagnetic shielding performance can reach 39.5 d B.At the same time,the aerogel has good mechanical properties(1.6 MPa),photothermal properties and electrothermal properties.The aerogels coated with silica gel also have good hydrophobicity(138°).This study provides a new way of thinking for multi-channel applications of composite aerogels. |
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