Study On Preparation And Properties Of Ferrocene-based Conductive Polymer/Carbon Material Composites For Electromagnetic Interference Shielding

With the development of modern technologies such as telecommunication instruments and scientific electronic devices,a large amount of electromagnetic(EM)radiations are produced,which lead to harmful effects on the highly sensitive electronic devices and the surrounding environment.At present,the shielding materials are widely used to solve this problem and minimize the effect of EM radiation.In electromagnetic interference(EMI)shielding,reflection and absorption are the main mechanisms of EM radiations.For the reflection of EM radiations,the materials must have mobile charge carriers,while the absorption of radiations depends on the electric and magnetic dipoles,which interact with the EM field in the radiation.As a result,shielding materials need to be electrically conductive.It is also very important to have good connectivity within the conduction path.In this scenario,polymer-based composites containing conductive fillers such as carbon black(CB),carbon nanotubes(CNTs)and graphene have gained enormous attention as EMI shielding materials due to their unique properties such as excellent connectivity in the composite materials as a conductive filler,good electrical,thermal and EMI shielding properties.These composites have promising applications in the EMI shielding field especially in the areas of electronics,aerospace,aircraft,wearable devices,automobiles and so on.The ferrocene-based conductive polymer composites containing conductive fillers are useful for EMI shielding effectiveness(EMI SE)because conductive polymers have the ability to transfer electron on the conductive fillers and ferrocene group has good redox properties.Therefore,ferrocene-based conductive polymers may promote conductive properties of the composites which are essential for EMI shielding performance.In our research,we prepared different ferrocene-based conductive polymer/carbon material composites containing multiwalled carbon nanotube(MWCNT),reduced graphene oxide(RGO)and CB respectively and their EMI shielding properties and mechanism were studied.1)Ferrocene-based polythiophenes(PTFc)composites containing MWCNT,RGO and CB were prepared through chemical oxidative polymerization,respectively.The prepared PTFc/MWCNT,PTFc/RGO and PTFc/CB composites were characterized by scanning electron microscope(SEM),transmission electron microscope(TEM),fourier transform infrared(FTIR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TGA).Electrical conductivity of the PTFc/MWCNT,PTFc/RGO and PTFc/CB composites was measured by a typical four-probe method.The electrical conductivity measurements indicated that the PTFc/MWCNT,PTFc/RGO and PTFc/CB composites showed good electrical conductivity.EMI SE of the PTFc/MWCNT,PTFc/RGO and PTFc/CB composites was measured by a coaxial method in the frequency range of 1-4.5 GHz.The total shielding effectiveness(SET)achieved for PTFc/CB,PTFc/RGO and PTFc/MWCNT composites was-10.46 dB,-11.27 dB and-24 dB at 50 wt%composite sample loading in the paraffin wax,respectively.2)Ferrocene-based polypyrrole(PPyFc)composites containing MWCNT,RGO and CB were successfully prepared by chemical oxidative polymerization,respectively.The prepared PPyFc/MWCNT,PPyFc/RGO and PPyFc/CB composites were characterized by SEM,TEM,FTIR,XRD,XPS and TGA.Electrical conductivity of the PPyFc/MWCNT,PPyFc/RGO and PPyFc/CB composites was tested by a typical four-probe method.EMI SE of the PPyFc/CB,PPyFc/RGO and PPyFc/MWCNT composites was measured through a coaxial method in the frequency range of 1-4.5 GHz.The SET achieved for PPyFc/CB,PPyFc/RGO and PPyFc/MWCNT composites was-11.08 dB,-11.44 dB and-23.74 dB at 50 wt%composite sample loading in the paraffin wax,respectively.3)Ferrocene-based polyfuran(PFMFc)composites containing MWCNT,RGO and CB were successfully prepared via chemical oxidative polymerization,respectively.The morphology,grafting,crystal structure,elemental speciation and thermal stability of the prepared PFMFc/MWCNT,PFMFc/RGO and PFMFc/CB composites were analyzed by SEM,TEM,FTIR,XRD,XPS and TGA.Electrical conductivity of the PFMFc/MWCNT,PFMFc/RGO and PFMFc/CB composites was measured using the typical four-probe method,and the PFMFc/MWCNT,PFMFc/RGO and PFMFc/CB composites showed good electrical conductive property,Furthermore,the EMI shielding properties of the PFMFc/MWCNT,PFMFc/RGO and PFMFc/CB composites were measured via a coaxial method at 1-4.5 GHz frequency range.The SET obtained for PFMFc/CB,PFMFc/RGO and PFMFc/MWCNT composites was-8.71 dB,-9.86 dB and-20.60 dB at 50 wt%composite sample loading in the paraffin wax,respectively.4)Ferrocene-based polyimidazole(PPIFc)composites containing MWCNT,RGO and CB were prepared by chemical oxidative polymerization,respectively.The prepared PPIFc/MWCNT,PPIFc/RGO and PPIFc/CB composites were characterized by SEM,TEM,FTIR,XRD,XPS and TGA.The electrical conductive property of the PPIFc/MWCNT,PPIFc/RGO and PPIFc/CB composites was studied by a typical four-probe method.The EMI shielding properties of the composites were measured by a coaxial method at 1-4.5 GHz frequency range.These PPIFc/MWCNT,PPIFc/RGO and PPIFc/CB composites showed good EMI shielding performance and SET for PPIFc/CB was-11.2 dB,PPIFc/RGO was-13.1 dB and PPIFc/MWCNT was-25.4 dB by using 50 wt%of the composite in the paraffin wax.