Fabrication Of Flexible Polymer Nanofiber/metal Nanoparticles Hybrid Membranes For High-performance Electromagnetic Interference Shielding

With the wide application of modern telecommunications and various electronic equipment,an increasingly dense and intensive electromagnetic interference?EMI?of radio frequency radiation has been become a new serious pollutant source in addition to noise,water and air pollution,which seriously affects human health and the normal function of sensitive electronic apparatus and systems.To tackle the problem,great efforts have been made for the development of high-performance EMI shielding material?EMI SM?which can shield high energy and broadband radiation effectively.In the last few years,a lot of studies have made great progress on lighter,thinner and more flexible EMI-shielding materials with even higher shielding efficiency.Materials with good EMI shielding performance are depending on the high electrical conductivity,including metal,carbon and electrical conductive polymer.It is well known that metal shrouds are good choice as EMI shielding materials due to their high electrical conductivity and excellent workability.However,they are suffering from poor mechanical flexibility and exceedingly high weight for practical applications.To resolve this problem,much work has been done to study polymer-metal composites.Recently,polymer-metal composites were fabricated by mix metal particles and nanowires with polymer by simple mechanical mixture or foaming process.However,a low content of conductive fillers leads to a poor conductivity of the polymer-matrix composites,while a high content of conductive fillers usually result in an inferior mechanical property and processibility due to the severe agglomeration of the fillers.In this thesis,we report a highly flexible porous electrospun polymer NFs decorated with metal nanoparticles?NPs?membrane with an excellent EMI shielding performance in X-band,Ku-band and K-band.All free-standing hybrid membranes are fabricated via an electrospinning followed by electroless deposition process.The resultant CPAN NF/MNPs hybrid membrane,which possess good electrical conductivity and nano-size effect,shows excellent EMI-shielding efficiency,reasonable mechanical strength and excellent flexibility.The research results of this thesis mainly include three parts:1.To explore the electromagnetic shielding properties of magnetic metal materials.The CPAN NF/Ni NPs hybrid membrane with a high efficiency and reasonable strength was prepared via an electrospinning followed by electroless deposition process.The best overall electromagnetic interference shielding properties could be achieved when the electroless deposition time is 90 min.For the CPAN NF/Ni NPs-90,the EMI SE could reach about 53.24 dB with a conductivity of1001.28 S?cm,specific EMI shielding effectiveness?SSE?and absolute EMI shielding effectiveness?SSE_t?can reach 40.49 dB?cm³?g^-1 and 11908.18 dB?cm²?g^-1.In addition,CPAN NF/Ni NPs-90 held a tensile strength of 11.88 Mpa and elongation at break of8.36%.2.The crosslinking polyacrylonitrile?CPAN?nanofiber?NF?/Cu nanoparticles?NPs?hybrid membrane with a high efficiency and reasonable strength was prepared via an electrospinning followed by electroless deposition process.The best overall electromagnetic interference shielding properties could be achieved when the electroless deposition time is 90 min.For the CPAN NF/Cu NPs-90,the EMI SE could reach about 57.69 dB with a high conductivity of 10004.61 S?cm,specific EMI shielding effectiveness?SSE?and absolute EMI shielding effectiveness?SSE_t?can reach 49.31 dB?cm³?g^-1 and 14941.72 dB?cm²?g^-1.In addition,CPAN NF/Cu NPs-90held a tensile strength of 5.78 Mpa and elongation at break of 10.92%.3.In order to further improve the electromagnetic shielding performance,CPANNF)/Ag MNPs hybrid membrane with a high efficiency and reasonable strength was prepared via an electrospinning followed by electroless deposition process.The best overall electromagnetic interference shielding properties could be achieved when the electroless deposition time is 90 min.For the CPAN NF/Ag NPs-90,the EMI SE could reach about 83.50 dB with a high conductivity of 61110.65 S?cm,specific EMI shielding effectiveness?SSE?and absolute EMI shielding effectiveness?SSE_t?can reach 39.39 dB?cm³?g^-1 and 11254.43 dB?cm²?g^-1.In addition,CPAN NF/Cu NPs-90held a tensile strength of 18.02 Mpa and elongation at break of 9.99%.