Study On Preparation, Characterization And Performance Of Magnetic Function Materials Of Composite

The magnetic function materials have being widely used and have tremendouspotential applications in many fields owing to its particularity. Much research work hasbeen done in novel magnetic function materials from various perspectives of differentsubjects. Among which, the materials of magnetic polymer micro-spheres, lightmagnetic powder and multifunctional composite magnetic coating are relativelyoutstanding kinds. Although the investigation in both fundamental principles andapplication is continuing to further, yet there remains many questions worth to beexplored. As to magnetic polymer micro-spheres, the problems lie in the less effectivetechnique for preparation and difficulty in choice of monomer, which hinders theenlargement in applied fields. As light magnetic powder is concerned, it is worthwhileto conduct further investigations on how to plate on the matrix of powder byelectro-less way. For multifunctional composite magnetic coating, the challenge is todevelop new materials with versatile functions. The aim of the present work is,therefore, to exploit new kinds of magnetic function materials, and to make theirperformance perfect, so as to make them appropriate for practical application.Furthermore, novel ways and ideas are offered on how to exploit the facile modelmagnetic function materials. The main results are shown as follows:(1) The surface of Fe₃O₄ magnetic particles were embed byβ-CD polymer viautilizing the technique of emulsification and cross-linking, and the cross-linkedβ-CDpolymer micro-spheres with magnetic-conductivity were prepared. The effects ofdosage of emulsifying agent OP,β-CD and epichlorohydrin on the particle size ofmagnetic micro-sphere and the magnetic responsive ability were discussed, and theoptimum conditions were therefore obtained. The morphology, phase structure,component and content of the magnetic cross-linkedβ-CD polymer micro-spheres werecharacterized by IR, XRD, EDS, TEM and TG. The results showed that the magneticmicro-sphere had core-shell structure. On this basis, a novel magnetic targetedcurcumin cross-linkedβ-CD polymer micro-spheres were prepared by inclusionreaction of curcumin with hydrophobic vacuum ofβ-CD. The effects of temperature,solution pH and dosage of curcumin on the inclusion reaction were also investigated.Besides, the parameters of magnetic susceptibility, magnetic responsive ability,localized quantity of magnetism and controlled release rate of drug of the magnetic carriers were determined, and the results showed that the magnetic cross-linkedβ-CDpolymer micro-spheres were the ideal carrier for targeted drug.(2) The magnetic micro-spheres of cross-linked Sodium Alginate were preparedby the embedding methods, namely the magnetic fluids were dispersed in the gelsolution of Sodium Alginate, and the macromolecular coating of cross-linked SodiumAlginate on the surface of Fe₃O₄ particles could be acquired by Glutaric dialdehydeused as cross-linker. The impact of the concentration of Sodium Alginate and thedosage of Glutaric dialdehyde, as well as the reaction temperature on the content ofFe₃O₄ and particle diameter of the magnetic micro-spheres were studied, and theoptimized conditions were determined The structure of cross-linked Alginate Sodiummagnetic micro-spheres was characterized by methods of TEM, IR, DSC, TG and XRD.The results showed that a core-shell structure occurred in the magnetic micro-sphereswhich was consistent with the expectation. The immobilized magnetic Trypsin hadbeen prepared by absorbing and cross-linking Trypsin onto the carrier of thecross-linked Sodium Alginate magnetic micro-spheres. The effects of adsorption time,amount of enzyme, concentration of Glutaric dialdehyde, pH in the process ofpreparation on the activity of magnetic immobilized enzyme had been investigated,and The optimum conditions for immobilizing enzyme were given. Study on theproperties of immobilized enzyme illustrated that the immobilized magnetic Trypsinhad superior stability and catalytic performance to natural Trypsin. The cross-linkedSodium Alginate magnetic micro-sphere was an ideal candidate of carrier toimmobilize enzyme.(3) The there kinds of polymer-based magnetic powders were prepared byelectro-less plating Ni-P-Fe, Ni-P and Co-P magnetic coatings onto polymericpowder. The effects of a variety of factors on the yield of magnetic powder wereexplored, the optimized conditions of electro-less plating process were obtained byorthogonal experiments. The morphology, phase structure, component and content ofthe above-mentioned three kinds of polymer-based magnetic powder werecharacterized by SEM, XRD, EDS, and the dimension and diameter distribution ofparticles were measured by the analytical instrument with laser; and the magnetichysteresis loop was measured by use of vibrational sample magnetization instrument.The results indicated that these three kinds of magnetic samples have superpapramagnetion, non-crystal structure and ball-shaped appearance under the optimizedplating condition as mentioned above. The new MR fluids were prepared by using thenovel polymer-based magnetic powder taking place of traditional magnetic particles. The anti-sedimentation stability and the change in viscosity of novel MR fluids undermagnetic field were explored, indicating that anti-sedimentation stability was good,but the magnetic responsive-ability needs to be improved.(4) The plated Ni-P-W-α-Al₂O₃ composite coatings with functionality wereprepared by the technique of composite electro-deposition. The impact of conditions ofelectro-deposition on coatings appearance, the deposition rate and the content ofα-Al₂O₃ in coatings were discussed, which included the particle size ofα-Al₂O₃, itscontent and dispersed method in electrolysis, the concentration of Na₂WO₄ inelectrolysis and the current density, as well as the pH value of electrolysis, and anoptimized conditions for the composite electro-deposition was obtained. Themorphology, the phase structure, the component and content of Ni-P-W,Ni-P-W-nmα-Al₂O₃ and the Ni-P-W-μmα-Al₂O₃ composite plated functional coatingswere measured by SEM, XRD and EDS, proving these three coatings being non-crystalstructure under the optimized plating conditions, and having the tendency to formcrystal structure after heat treatment. The surface of plated coating also presentedvesicles with various dimensions. However, there are no obvious vesicles on thesurface of coatings containingα-Al₂O₃ particle. The component and content the surfaceof coatings were given by EDS. All these results indicated thatα-Al₂O₃ particles hadbeen embedded in coatings. The hardness, the properties of anti-oxidation andcorrosion resistance of Ni-P-W, Ni-P-W-nmα-Al₂O₃ and Ni-P-W-μmα-Al₂O₃ platedcoatings were measured, indicating that (a) the hardness and the anti-oxidationproperty had a better performance than alloy plated coatings of the Ni-P-W, andNi-P-W-nmα-Al₂O₃ had the outstanding properties; (b) the corrosion resistance ofplated composite coatings was, however, not improved much than that of the Ni-P-Walloy plated coatings. As a result, the purposes of improving the performance of theplated coatings were accomplished by the composite technique. The Ni-P-W-PTFEplated coatings were prepared in a similar method as that of Ni-P-W-α-Al₂O₃ ones, andtheir structures and performances were measured too. The results showed that therewas no obvious improvement in the hardness, the properties of anti-oxidation andcorrosion resistance for Ni-P-W-PTFE plated coatings than that of Ni-P-W alloycoatings except the wear resistant property.