Preparation And Microwave Absorption Properties Of Polyaniline/Magnetic Nanoparticle Composites

As a conducting polymer,polyaniline has the advantages of light weight,simple prepa-ration,low cost and easy control of permittivity.In this paper,to get highly conductive polyaniline we explored the acid and alkaline polymerization environment of aniline.Then we combined polyaniline with magnetic nanoparticles of Co S₂or Fe₃O₄to prepare strong,thin,light and wide absorber by improving the impedance matching characteristic and the microwave absorption performance.The prime contents are as follows:(1)Six groups of polyaniline were prepared in strong acid(HCl concentration is 1 mol/L,0.5 mol/L,0.1 mol/L),weak acid(p H=2),neutral(p H=7)and alkaline(p H=9)conditions by chemical oxidation,respectively.Then we measured the conductivity and microwave absorption of six groups of polyaniline.The conductivity of polyaniline generated in acidic environment is superior:when the test pressure is 20 MPa,the conductivity of polyaniline generated in the strong acid is 0.1(S/cm).Absorbing test show that the polyaniline grew in neutral and alkaline solution are ineffective in absorbing electromagnetic wave while the polyaniline grew in acidic solution have the potential for microwave absorption.(2)The magnetic nanoparticle(Co S₂)/polyaniline(PANI)composite were prepared by a two-step method(hydrothermal reaction and chemical oxidation polymerization).The elec-tromagnetic wave absorbing property of the Co S₂/PANI nanocomposite was adjusted by changing the mass ratio of aniline and Co S₂.When the mass ratio of aniline and Co S₂is 3:1,PAFS3 composite demonstrates favourable electromagnetic wave absorption characteristics:the strongest reflection loss can reach-54.6 d B at electromagnetic wave frequency of 12.1GHz and effective absorbing bandwidth is 4.76 GHz ranging from 9.63 to 14.39 GHz with corresponding thickness of 2.1 mm.(3)Magnetic nanoparticles(Fe₃O₄)/polyaniline(PANI)with core-shell structure were prepared by a single-mode microwave-assisted method.Aniline was polymerized by chem-ical oxidation on the surface of Fe₃O₄.When the Fe₃O₄is 68 mg and aniline monomer is200?L(the mass ratio of aniline to Fe₃O₄is 3:1),Fe₃O₄/PANI composite shows excellent absorbing performance:the strongest reflection loss of the composite reaches-55.5 d B with thickness of 1.6 mm,the relevant frequency is 17.3 GHz;meanwhile,the valid absorbing frequency bandwidth of Fe₃O₄/PANI with the thickness of 1.8 mm can reache 5.4 GHz.