The Preparation And Properties Of Acids Doped Conductive Polyaniline And Its Composites

Conductive polymers are called"synthetic metals"because of the complete delocalization ofπelectrons on the long chain aromatic polymer backbone.Among many conductive polymers,Polyaniline（PANI）has become one of the hot materials due to its low density,adjustable conductivity,good environmental stability,reversibility of doping and simple preparation process.The conductivity of PANI comes directly from its physical and chemical properties,such as molecular weight,crystallinity,redox level and morphology.In this article,the effect of doped acids on the conductivity of PANI was studied by chemical oxidation polymerization of aniline（An）in different acid solutions,and then the zinc-doped ferrite/conductive Polyaniline（ZFO/PANI）electromagnetic composites were prepared by the composite of conductive PANI and magnetic ferrite.The effects of different components on the structure,morphology and microwave absorption properties of the composites were studied by changing the addition of ferrite.The main research contents and conclusions are summarized as follows:（1）Conductive PANI was prepared by chemical oxidation polymerization in different acidic solutions.The effects of single acid and compound acids on the conductivity and yield of PANI were studied.Hydrochloric acid-doped Polyaniline（HCl-PANI）had the highest conductivity and yield,while acetic acid-doped Polyaniline（HAc-PANI）had the worst conductivity,indicating that the acidity of doped acid had a great effect on the conductivity of Polyaniline.In the composite acid-doped Polyaniline,the conductivity of aminosulfonic acid（SA）and HCl co-doped Polyaniline was the highest,up to 8.33 S/cm,and that of SA and HAc co-doped Polyaniline was 1.32 S/cm.The conductivity of the composite acid-doped Polyaniline was higher than that of the single acid-doped Polyaniline,which may be related to the synergistic action between the compound acids.（2）Conductive Polyaniline/sodium alginate composites（PANI/NaAlg）were prepared by oxidation polymerization with camphor sulfonic acid（CSA）and acetic acid as co-dopants in the presence of sodium alginate（Na Alg）.The effects of mol ar ratio of CSA to HAc,polymerization time and Na Alg concentration on the structure,morphology and conductivity of the composites were also investigated.The results showed that when the molar ratio of CSA to HAc was 0.4:1,the polymerization time was 4 h and the concentration of Na Alg was 1.0 wt%,the electrical conductivity of the composite reached the highest of 3.50 S/cm,and the yield was 67.63%.（3）Conductive PANI was prepared by emulsion polymerization using p-toluene sulfonic acid（p TSA）as emulsifier and dopant,L-aspartic acid（Asp）as template and dopant.The effects of amino acid species,molar ratio of Asp to An,concentration of p TSA and molar ratio of APS to An on conductivity and yield of PANI were researched.The results showed that when Asp and p TSA were used as dopants,the molar ratio of Asp to An was 1:2,the concentration of p TSA was 0.75 mol/L,and the molar ratio of APS to An was 1:1.The conductivity and yield of PANI reaced the highest,the conductivity reached 8.00 S/cm,the yield of PANI was as high as121.28%.（4）Divalent zinc-doped spinel ferrite Zn_0.2Fe_2.8O₄（ZFO）was prepared by solvothermal method,ZFO/PANI electromagnetic composites were prepared by in-situ polymerization of PANI conductive layer on the surface of ZFO.The effect of different components on the structure,morphology,electromagnetic properties and microwave absorption properties of ZFO/PANI was investigated by changing the content of ZFO.The results showed that the composite of magnetic ZFO and conductive PANI can improve the electromagnetic wave absorption property of the composite.When the mass ratio of ZFO to An was 1:2,the mass ratio of composite to paraffin was 1:1,the thickness of absorbing agent was 2.3 mm,the maximum reflection loss at 11.12 GHz reached-48.07 d B,the electromagnetic wave frequency with reflection loss less than-10 d B was between 9.66-12.95 GHz and the effective absorption bandwidth was 3.29 GHz.The enhanced microwave absorptio n performance of the composite was mainly related to the better impedance mat ching property of the composite.The polarization relaxation process and eddy current loss in the composites were also beneficial to improve the absorbing performance.