Investigation Of Amphiphilic Polymer Modified Magnetic Nanomaterials

Iron oxide nanoparticle has been applied in many fields for its small particle size,special magnetic properties and good biocompatibility.Amphiphilic polymers have usually been used to modify iron oxide nanoparticles to improve the dispersity and stability,and adjust the chemophysical properties through the composition and molecular weight of these polymers.In this thesis,different amphiphilic polymers were prepared to modify iron oxide nanoparticles via improved coprecipitation method,and magnetic nanomaterials with different microstructures were obtained through self-assembly of these nanoparticles.The as-synthesized nanomaterials were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,dynamic light scattering?DLS?,fourier transform infrared spectrophotometry?FTIR?,thermal gravimetric analysis?TGA?,and vibrating sample magnetometer?VSM?et.al.The effects of polymeric structure and slef-assemble behavior on the properties of nanomaterials were investigated.The linear amphiphilic polymer,polyethylene glycol?PEG?,with different molecular weights was selected as the modifier to prepare magnetite nanosheets.The result was confirmed that these nanosheets were formed by the self-assembly of PEG-modified Fe₃O₄ nanoparticles.Great stability in a wide pH range and different concentrations of salt solutions was found for these nanosheets,which displayed high adsorption capacity for Pb²⁺in aqueous solition even in the presence of protein.and other metal ions.Amphiphilic polymers with different amides were then choosen to modify magnetite nanoparticles.The effect of amino group on the properties of nanomaterials was investigated.No addition of any otherbases was required in this preparation.The results proved that amino group can significantly influence the crystal size and other properties of nanomaterials.Amphiphilic polymer hyPEI-g-?PCL?_n containing hyperbranched PEI was also selected to modify the magnetic nanoparticles.The water stability and dispersity of nanomaterials were improved due to the buffer capacity of hyperbranched PEI,resulting from the existence of different amino groups.The introduction of hydrophobic PCL segment increased the hydrophobic affility between polymer and magnetite nanoparticle.The results showed that hyPEI-g-?PCL?_n can efficiently decrease the remanence and coercivity of nanomaterials,comparing with PEI modified Fe₃O₄ nanoparticles.And the properties of nanomaterials can be controlled by the structure of hyPEI-g-?PCL?_n.In summary,using amphiphilic polymer to modify magnetic nanomaterials can not only improve the dispersibility and stability of the magnetic nanoparticles,but also induce the self-assembly of nanoparticles to form various superstructures with novel properties.