The Preparation And Characterization Of Feerimagnetic Particles/Polypyrrole (PPy) With Core-Shell Structure

Recently,conducting polymer composites with both electrical andferromagnetic properties have received tremendous attention.The mostgeneral method to obtain polymer conductive nanocomposites withmagnetism is that monomers are polymerized in an aqueous solution inthe presence of ferromagnetic particles.An obstacle in assembling andmaintaining dispersion in the composite is the aggregation of small ironoxide particles.In this paper,we present novel methods÷0 obtainferromagnetic particles with stable dispersion. Furthermore,ferromagnetic particles/PPy composites were synthesized.At themeanwhile,the effect of iron oxide content in the composite with respectto the electrical and ferromagnetic properties of PPy composites had beeninvestigated.The relationship between physical properties and structurewas discussed. Dodecylbenzene sulfonic acid(NaDBS)was used to dispose Feparticles,in order to obtain stable dispersion.Pyrrole monomer waspolymerized in the presence of Fe particles in the aqueous solutions.Theinfluence of electrical and magnetic properties on the dosages of oxidant,doper and Fe particles was discussed in this paper.Fe304 nanoparticles were synthesized by FeCl3+FeCl2 at theNH40H aqueous solution,and were disposed by alcohol to obtain Fe304nanoparticles with organized surface.Then pyrrole monomer waspolymerized in the presence of Fe304 particles.The conductivity ofPPy—Fe304 composites was much higher than that of pure PPy,andincreased with the increase of Fe304 content in composites.The saturatedmagnetization linearly increased with the increases of the Fe content. FeCl3 aqueous solution was used to dispose Fe304 nanoparticles.Because of common ion effect,Fe。+ion would be absorbed onto thesurface of Fe304 nanoparticles.Then Fe304 particles were surrounded bypositive charged(Fe3+)shells to prevent their aggregation.At.the sametime.the Fe"ion shell was the oxidant to polymerize pyrrole monomer.PPy.Fe304 composite had low conductivity(σ<10-2S/cm),for the limitedof the amount of FeH ion on the surface of Fe304 particles.The PPy layerwas 1-2 nm.The more oxidant and pyrrole monomer were added to theacting system in order to obtain PPy—Fe304 composite with highconductivity.The conductivity of PPy—Fe304 composites was muchhigher than that of pure PPy,and increased with the increase of Fe304content in composites.The saturated magnetization linearly increasedwith the increases of the Fe content.The composites have low coerciveforce,which meant they would be made as electric—magnetic shieldsmaterial.