| Fe3O4hollow nanomicrospheres were prepared by a solvent-thermal methodwith PVP as additive agent in this work and effects of temperature, reaction time andthe amount of alkali on morphology and size of the products were studied. Theprobable formation mechanism of hollow nanomicrosphere using PVP as additiveagent was suggested as well. The Fe3O4nanomicrospheres which were coated withsilica and meso-porous silica intended to increase stability and specific surface arearespectively were organically functionalized to improve their hydrophobicity and usedfor oil-absorption capability study. Fe3O4nanoparticles prepared by chemicalco-precipitation were doped added into hollow CaCO3obtained through doubledecomposition reaction. The drug release behavior of IBU in magnetic hollow CaCO3composite microspheres was also investigated. The concrete experiment content andthe main results are as follows:(1) Highly dispersed magnetic hollow microspheres were prepared by a solventthermal method with glycol as a solvent and reducing agent. In the system, NaAcwas added as an electrostatic stabilizer and a basic catalyst.Polyvinylpyrrolidone(PVP) was considered as a guide agent for hollow structureand a preventative measure against particle agglomeration. The highly dispersedmagnetic hollow spheres were characterized by X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS), Vibrating sample magnetometer(VSM)and Transparent electron microscopy(TEM). The results indicated that themagnetic hollow spheres with low coercivity, high dispersity, homogeneous sizeand high crystallinity showed high saturation magnetic intensity (81.9emu/g).The effects of the experimental conditions including temperature, reaction time,solvent, the amount of substance of alkali and PVP on the product morphologyand size were studied and it was found that the optimum reaction temperature andtime were200℃and20h respectively.The amount of NaAc had little effect onthe product morphology, but diethylene glycol(DEG) addition would induced anon-hollow structure formation. The study of hollow microspheres formationmechanism showed that PVP not only served as stabilizer but also as a guide agent of the hollow structure.(2) Two kinds of core-shell nanomicrospheres Fe3O4@SiO2and Fe3O4@mSiO2wereprepared using a solvent thermal method and characterized in detail by TEM. Theresults showed that Fe3O4@SiO2had good dispersity with190nm core diameterand45nm shell thickness, while Fe3O4@mSiO2maintained the orderedmesopores with60nm shell thichness. The prepared Fe3O4@SiO2andFe3O4@mSiO2could be used for oil absorption via hydrophobic modification ofhydrophobic groups. The results indicated that oil adsorption capacity ofHpb-Fe3O4@SiO2and Hpb-Fe3O4@mSiO2for diesel oil was6.10g/g and9.74g/grespectively, and for motor oil was approximate to11.52g/g and15.73g/grespectively. The material could be reused for5-6times after regeneration.(3) Fe3O4magnetic nanoparticles were prepared by a chemical coprecipitationprocedure and characterized by XRD, XPS, TEM. And then two kinds ofmagnetic nanoscale composite micropheres Fe3O4/CaCO3and Fe3O4&CaCO3were synthesized through dopping Fe3O4particles into the structures of calciteCaCO3obtained by a double decomposition reaction coupled precipitation.Characterizztion reults by TEM, SEM, XRD, VSM and BET showed thatFe3O4/CaCO3was solid sphere with a diameter of2-3μm, while Fe3O4&CaCO3was hollow with a diameter of4μm. The vitro loading and release test ofFe3O4/CaCO3and Fe3O4&CaCO3was conducted selecting ibuprofen(IBU) as smodel drug. The maximum drug loading of Fe3O4/CaCO3and Fe3O4&CaCO3were43mg/g and116mg/g respectively. The maximum releasing rate of IBU-Fe3O4/CaCO3and IBU-Fe3O4&CaCO3in PBS buffer solution (pH=7.4,Simulated intestinal fluid) was99%in16h and90%in20h respectively. It isalso found that the releasing kinetics of IBU accorded with first-order model. |
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