The Research Of Light-weight Hollow Microsphere Composites With Electromagnetic Properties

With the development of science, people begin to pay attention to manufacturefunctional materials. Hollow microsphere composites have attracted considerableacademic and technological attention because of their unique physical propertieslike low effective density and high specific surface. Meanwhile, the electromagneticmaterials play an important role in applications as electromagnetic shielding andwave-absorbing materials and so on. In this dissertation, polyaniline（PANI） andFe₃O₄nanoparticles were used as conductive and magnetic materials. Respectively,polystyrene（PS） beads and hollow glass microspheres（HGS） were used as templateor substrate to prepare light-weight hollow composite microspheres withelectromagnetic properties. The morphology and composition of the light-weightelectromagnetic composites were characterized by means of FTIR、SEM、XRD、EDX、TGA、XPS and Zeta potential analyses. The conductive and magneticproperties of the resultant products were characterized by conductivity measurementand vibrating-sample magnetometry. The principle of preparation was proposed aswell.Firstly, the polystyrene （PS） beads were sulphonated to derive sulfonic acidgroups which induced Fe₃O₄nanoparticles to adsorb and consequent growth ofpolyaniline, and then, the PS cores were selectively dissolved to yield hollowcomposite microspheres with electromagnetic properties. A series ofcharacterization methods were applied. The content of Fe₃O₄nanoparticles adsorbedon template can be controlled by changing the sulphonated degree. The coatingamounts of polyaniline were remarkably enhanced after using the polyvinylpyrrolidone （PVP） to modify sulfonated PS（SPS）/Fe₃O₄beads. Hollow microspherecomposites with high saturated magnetization and conductivity were prepared. Thehighest saturated magnetization of hollow microsphere composites could reach9.13emu/g, and the highest conductivity was1.27S/cm.The silane coupling agent was used to modify hollow glass microspheres（HGS）. The effects of the reaction parameters of the silane coupling agentmodification on the structure of HGS were investigated. HGS coated by polystyrenewere obtained through the polymerization of styrene with the double bonds on thesurface of the grafted HGS. HGS modified by polystyrene was sulphonated toadsorb Fe₃O₄nanoparticles. Finally, HGS/SPS/Fe₃O₄/PANI hollow compositemicrospheres with electromagnetic properties were prepared after in situpolymerization of aniline monomer on the surface of HGS/SPS/Fe₃O₄. The analysis results showed that the content of sulfonic acid groups played an important role onadsorbing Fe₃O₄nanoparticles. The saturated magnetization of the compositematerials reached11.707emu/g, and the conductivity was by orders of magnitude of10^-3, which were higher than the reported values.PS-modified HGS with good dispersion was obtained by the improvedpolymerization of styrene process. The Zeta potentials of Fe₃O₄nanoparticles andsulfonated PS-modified HGS on the different pH values were investigated. Theinfluences of the polymerization condition of styrene and sulphonated degree on thestructure of the HGS and its adsorption quantity for the Fe₃O₄nanoparticle werestudied as well. The results showed that with the enhancement of sulphonateddegree, adsorption quantity of the Fe₃O₄nanoparticles was increased. Themodification of PVP led to the conductivity of composite materials greatly improved.The saturated magnetization of-NH2, and sulphonated groups-modified HGSderived composite materials was3.8emu/g,1.8emu/g and3.9emu/g, respectively.The conductivity was by order of magnitude of10^-1.