Preparation And Properties Of Functionalized Magnetic Nanoparticles

Because of the advantages of superparamagnetism and large specific surface area of magnetite（Fe₃O₄）colloidal nanoparticles,they have demonstrated great application potentials in the fields including mass separations,drug delivery synstems,sensors and catalysts.Magnetic nanoparticles are prone to aggregate due to their high surface energy,thus limiting their practical applications to a certain extent.Therefore,making functionalization modification on their surface is especially important.In this thesis,a novel type of thermosensitveβ-CD-polymer-brushes modified magnetic nanoparticles（Fe₃O₄@PDA@PNG-CD）have been successfully fabricated by decorating the surface of magnetic Fe₃O₄ nanoparticles using poly（N-isopropylacrylamide）（PNIPAM）with excellent thermoresponsivity andβ-cyclodextrin（β-CD）with fascinating molecular recognition property.And the chiral ressolution property of the resulted Fe₃O₄@PDA@PNG-CD toward tryptophan enantiomers（DL-Trp）were also systematically investigated in this work.Moreover,aiming at the bad solvents compatibility of the currently magnetically-responsive photonic crystals（MRPCs）based on Fe₃O₄ collodial nanoparticles,are generally applicabe in aqueous systems,we developed another kind of MRPC（Fe₃O₄@MPS）with excellent solvent compatibility by modifying the surface of Fe₃O₄ collodial nanoparticles with a silane coupling agent?-methacryloxypropyltrimethoxysilane（MPS）.The achieved Fe₃O₄@MPS could be used in water and several organic solvents.The detailed studied contents and results are as follows:1)Fe₃O₄ colloidal nanoparticles were firstly synthesized by a one-step solvothermal method.Then,the thermosentiveβ-CD polymer brushes decorated magnetic Fe₃O₄ colloidal nanoparticles（Fe₃O₄@PDA@PNG-CD）were achieved by combining surface-initiated atom transfer redical polymerization（SI-ATRP）and ring-opening reaction of epoxy groups from PNG chains using N-isopropylacrylamide（NIPAM）and glycidyl methacrylate（GMA）as the functional monomers,and the chiral separations of DL-Trp by the Fe₃O₄@PDA@PNG-CD were also fully studied.The obtained results indicate that the Fe₃O₄@PDA@PNG-CD have satisfactory chiral resolution performances toward DL-Trp.Theβ-CD units and PNIPAM component on the surface of the functional nanoparticles played significant roles in the enantioseparation of DL-Trp.Furthermore,operational temperatures and DL-Trp initial concentration also had important effects on the resolution of DL-Trp.Also,the Fe₃O₄@PDA@PNG-CD developed in this study also owned excellent recyclability,which could serve as a promising chiral nanoselector for direct enantioseparation of chiral compounds.2)Fe₃O₄ colloidal nanoparticles were firstly synthesized by modified solvothermal method.Then,Fe₃O₄@MPS with excellent solvent compatibility,which could be applicable in water and several organic solvents,was synthesized by surface modification of the obtained Fe₃O₄ colloidal nanoparticles with MPS.The polarity of the investigated solvents greatly affected the photonic property of the obtained Fe₃O₄@MPS.The stronger the polarity of the solvents,the better the photonic property.The developed functional nanoparticles show significantly potential applications in the fields of display,anticounterfeiting and sensors and so on.