Preparation Of Superhyfrophobic Conductive Composite Fabric And Its Application In Electromagnetic Interference Shielding

With the advent of the 5g communication era,the development of various electronic communication devices has made people's lives more convenient while inevitably causing more and more electromagnetic interference(EMI)problems.These high-frequency electromagnetic radiations will not only interfere with the normal operation of sophisticated electronic equipments,but also do harm to people's health.Traditional metallic materials are widely used in electromagnetic shielding by virtue of their excellent conductivity,but their disadvantages such as high density,poor corrosion resistance and flexibility limit their applications in the area of wearable electronics.In this thesis,superhydrophobic EMI shielding composite fabrics are prepared by modifying metal nanoparticles on the surface ofcommercial fabric backbones and enhancing the interaction between them through interfacial modification,and finally modulating the surface topology and hydrophobizing them to overcome the above disadvantages of metal materials.The paper consists of three parts as follows.1.Firstly,the chemically active polydopamine layer(PDA)is modified on the surface of inert polypropylene(PP)fibers by the self-polymerisation of dopamine,followed by introducing silver nanoparticles(AgNPs)on the surface of the fibers by dip-coating.Finally the superhydrophobic conductive composite fabric can be obtained by hydrophobic treatment with 1H,1 H,2H,2H-perfluorodecanethiol(PFDT).The superhydrophobic fabric shows the high conductivity of 4000 S/m,the contact angle of about 155°,the average electromagnetic shielding effectiveness(SE)and the specific electromagnetic shielding effectiveness(SSE)up to 48.2 dB and 209.56 dB cm3 g-1,respectively.Owing to the interfacial interaction between the fibers and the AgNPs improved by PDA layer,the fabric shows a slight decrease in various performances after several mechanical tests.In addition,the constructed superhydrophobic surface improves the stability of the Ag layer,ensuring the reliability of the conductive fabric for EMI shielding in humid environments.2.The PP/PDA/AgNPs conductive fabrics are modified by polydimethylsiloxane(PDMS)instead of PFDT,thus preparing the superhydrophobic conductive fabrics with stable surfaces and high durability.The PDMS layer not only endures the fabric superhydrophobicity,but also acts as the "glue" to strengthen the interfacial interaction between the silver nanoparticles and between the silver nanoparticles and the fibers.In addition,fabrics modified with PDMS can load more AgNPs and possess a higher electrical conductivity and environmental stability compared with the composite fabric modified with fluorine molecules Even after severe mechanical abrasion and acid immersion corrosion,the composite fabric still exhibits the stable EMI shielding effectiveness,which is promising for EMI shielding in extreme environments.3.The commercial PP fabric fibers are firstly modified with a large number of hydrophilic functional groups(e.g.-OH,-COOH,etc.)by O2 plasma treatment,which is advantageous for forming conductive Ag layer on the fiber surface in the next step of electroless plating,followed by spray-coating with a mixture of ferric oxide nanoparticles(Fe3O4)and PDMS by a spraying gun at a certain pressure.The superhydrophobic and multi-functional composite fabric PP@AFP can be obtained after cured.The cured cross-linked PDMS improves the interfacial adhesion between the metal nanoparticles and the fibers,ensuring the surface stability and durability of the fabric.Moreover,the introduction of Fe3O4 nanoparticles and the construction of a dual core-shell structure improve the absorption capacity of the composite fabric for electromagnetic waves,effectively reducing secondary pollution of electromagnetic wave.In addition,the composite fabric shows excellent electro-thermal and photo-thermal performance and maintains excellent mechanical property even in extremely cold environments.This composite fabrics(PP@AFP fabric)open up new paths for the design of next generation wearable multifunctional electronic devices.