Preparation,Structure And Properties Of Janus Structural Absorbing Materials

Janus is a class of materials with asymmetric structure and dual chemical properties.Due to its unique structure and excellent performance,it has been widely used in various fields with great potential.However,most of the research on Janus materials at home and abroad focuses on the design and preparation of functional Janus and the application of biomedicine,photocatalysis,solubilizer,emulsifier,etc.,while the application of electromagnetic wave absorbing materials is rarely reported.In order to explore the structure of Janus materials with good wave absorption properties and develop new high-performance absorbing composite materials,this paper designs and prepares conductive metallic silver and magnetic iron tetroxide-coated Janus materials,and carries out the structural design and preparation of Janus materials and multi-walled carbon nanotube（MWCNT）composites and their absorption properties,which is of great significance for broadening the application of Janus materials.The main research contents of this paper are as follows:（1）SiO₂@PDVB/PS（J）Janus particles were synthesized by seed emulsion polymerization and phase separation method,the above Janus particles were amino modified,and Ag nanoparticles were coated on the surface of Janus particles by in-situ reduction method,and Ag@J Janus particles were prepared.The Ag@J Janus particles were characterized by FT-IR,SEM,TEM,XRD,TGA,EDS,Zeta potential,etc.,and the results showed that Ag@J Janus particles were successfully prepared,and the content of Ag in Ag@J Janus particles was regulated from 36.40wt%to 87.30wt%.（2）Research on the design and construction of Janus granular/MWCNT composites and their absorption properties.In order to improve the absorption performance of Ag@J composites and broaden the effective absorption band,a composite with Ag@J/MWCNT=9/1 was prepared.SEM,TEM and vector network analyzers were used to characterize the materials,and the results showed that when the silver content in Ag@J composites was 36.40wt%,the composites with Ag@J-1/MWCNT=9/1 showed the best absorption performance.When the thickness of the composite is 5.5mm,its minimum reflection loss（RL）value is-27.6d B（17.6GHz）,and the effective absorption bandwidth is 0.8GHz（17.2～18GHz）.In addition,the absorption mechanism of multi-heterogeneous structures is also discussed.（3）Fe₃O₄@PAN@PS hollow spherical nanocomposites（Mag@P）were prepared by seed emulsion polymerization and co-precipitation method,and the materials were characterized by SEM,TEM,FT-IR,EDS,Zeta potential,TGA,XRD,Vector network analyzer and other means,and the results showed that Mag@P nanocomposites were successfully prepared,when the content of Fe₃O₄ nanoparticles in Mag@P composites was 37.63wt%,The composite exhibits the best microwave absorption performance,with a minimum reflection loss value of-26.9 d B（17.4 GHz）,a thickness of 5.5 mm,and an effective absorption bandwidth of 0.3 GHz（17-17.3 GHz）.In order to improve the absorption performance of Mag@P composites and strengthen their absorption frequency bandwidth,Mag@P/MWCNT=9/1 composites were prepared.The test results show that when the content of Fe₃O₄ in the Mag@P composites is 28.59wt%,the composite with Mag@P-2/MWCNT=9/1 shows the best absorption performance,RLmin=-41.4d B（14.5GHz）,the thickness is only 2mm,and the effective absorption bandwidth reaches 5.9GHz（12.1-18GHz）.