Preparation, Characterization And Microwave Absorbing Properties Of Composite Of Ferrites/Chiral Polyaniline Induced By Chiral Camphorsulfonic Acid

As a special kind of conducting polymers, chiral polyaniline has good applicationprospect in microwave absorption due to the low frequency sensitivity, light weight,good chemical stability, low cost and good microwave absorption, which becomes aresearch hot in microwave absorbing materials.In the present work, chiral polyaniline/BaFe12O19(BF) composites weresynthesized by in situ polymerization using L-camphorsulfonic acid (L-CSA) as chiraldopant with BF particles modified by3-aminopropyltrimethoxysilane (APTS), in whichammonium persulfate (APS) was acted as the initiator. The effects of modification,dosage of L-CSA and BF particles, and chiral structure on electrochemical performanceand microwave absorbing properties were discussed.The results indicated that: When compared with PANI/BF composite beforemodification, the electrochemical performance and microwave absorbing properties ofPANI/BF composite after modification were better. When in the condition of ice-waterbath, the molar ratio of L-CSA:An is1.5, APS:An=1, the mass ratio of BF:An=0.5andthe reaction time is15h, the chiral PANI-APTS-BF composite prepared by in situpolymerization has the best microwave absorbing properties. Fourier infraredspectrometry (FT-IR) results suggested that the interaction had existed at the interfacesof PANI and BF particles rather than simply physical blend. The calculated reflectionloss results showed that a minimum reflection loss (RL) of-30.5dB was observed at33.25GHz with a thickness of only0.9mm, and the effective absorption bandwidthwith RLbelow-10dB reached12.8GHz (26.5-39.3GHz), which almost covered thewhole Ka band (26.5-40GHz).Fe3O4is the strongest magnetic nanoparticles of all natural mineral on earth withhigh Curie temperature, stability and controllable magnetism. In this work, Fe3O4wasadded into the polymerization system of PANI to prepare PANI/Fe3O4composite. Theeffects of dosage of Fe3O4on conductivity, electromagnetic parameters and microwaveabsorbing properties were discussed. Double-layer microwave absorbers were designedbased on PANI and PANI/Fe3O4composite with a total thickness of1mm.When the mass ratio of Fe3O4:An was1, microwave absorbing properties ofPANI/Fe3O4composite was the best, the minimum reflection loss was-37.4dB with acoating thickness of1mm, the effective absorption bandwidth reached11.53GHz. When PANI was acted as matching layer and PANI/Fe3O4composite was acted asabsorbing layer, in which the thickness of matching layer and absorbing layer were both0.5mm, the minimum RLof double-layer microwave absorber was enhanced to-54dB.While, when the absorbing layer is PANI with a thickness of0.4mm, and the matchinglayer is PANI/Fe3O4composite with a thickness of0.6mm, the effective absorptionbandwidth was enhanced to11.8GHz.