Preparation Of Highly Conductive Carbon/Organic Polymer Composites And Regulation Of Electromagnetic Shielding Properties

With the development of production and life,the use of a large number of electronic and electrical equipment will bring electromagnetic radiation.Electromagnetic pollution has become another safety hazard after light pollution and noise pollution.The multifunctional electromagnetic shielding film can shield most electromagnetic waves and has the function of electric heating and optical self-heating,which has become a hot spot of development.An electromagnetic shielding film which can continuously control the shielding performance by electrothermal and photothermal conditions has a broad application prospect.In this paper,Ag/CNFs/BC Janus films and GNPs/PLA Janus films were prepared us-ing Ag/CNFs（Ag/CNFs）,Graphite Nanoplatelets（GNPs）as conductive fillers,and organic polymers of bacterial cellulose（BC）and polylactic acid（PLA）as flexible substrates.The research content of this paper is as follows:（1）Ag/CNFs was prepared by environmental protection chemical deposition method,and the bacterial cellulose was fully dispersed by cell crusher.Ag/CNFs/BC Janus film was prepared by vacuum filtration device.The substrate of the composite film is bacterial cellu-lose layer,and the conductive layer is Ag/CNFs.Ag/CNFs60/BC Janus film has increased its conductivity to 4184 S/m,greatly improving the electromagnetic shielding performance.Ag/CNFs60/BC Janus film with a thickness of 34μm has an electromagnetic interference shielding（EMI SE）of 55 d B in the X-band（8-12 GHz）.In addition,Ag/CNFs60/BC Janus films also show good multifunctional thermal applications.The Joule heat saturation tem-perature reaches 110℃ at 3 V DC,and the photothermal conversion temperature reaches 60℃ at an optical power density of 200 m W cm^-2.These results show that Ag/CNFs/BC Janus films have good electromagnetic shielding performance as flexible self-heating products and have great application potential.（2）PLA particles,a shape memory polymer,were dissolved in methylene chloride（DCM）and dried to obtain PLA films.GNPs/PLA Janus film was obtained by laying GNPs with high conductive filler on the surface of PLA film,drying at room temperature for 12 h and hot pressing.The electromagnetic interference shielding performance of GNPs50/PLA Janus film reaches 50 d B in the frequency range of 5.88-26.5 GHz.GNPs50/PLA Janus film has good Joule heating performance,and the temperature can rise to 127℃under the heating voltage of 2 V.Based on the shape memory characteristics of PLA and the high electrical con-ductivity of GNPs,the shape of GNPs/PLA Janus film can be controlled by controlling the voltage,and then the electromagnetic shielding performance of GNPs/PLA Janus film can be controlled,realizing intelligent response.The GNPs surface of Janus films can be heated to 76℃at 200 m W cm^-2light intensity.Under the condition of illumination,the shape of the electromagnetic shielding film can be changed,and the electromagnetic shielding perfor-mance can be adjusted from 4 d B to 27 d B,realizing the adjustment of non-contact optical control electromagnetic shielding performance.GNPs/PLA Janus film will have outstand-ing application advantages in the following fields:applications with controllable shielding efficiency,shielding/absorbing power,and electrical conductivity,and it has potential appli-cation value in military security,actuators,etc.