【作者】 王娟；

【导师】 沈玉华；

【作者基本信息】 安徽大学 ， 应用化学， 2010， 硕士

【摘要】 本论文利用空气中的氧气氧化部分Fe2+,碱性条件下简单快速的制备出具有三种形貌的磁性纳米Fe3O4,此方法制备的Fe3O4非常稳定,可暴露于空气中不被氧化；利用纳米Fe3O4表面所带羟基与羧基之间进行酯化反应制备Fe3O4@油酸,经过修饰后的Fe3O4疏水性能优异,能很好的分散在有机溶剂中形成磁流体；用微乳液法制备Fe3O4/PS纳米复合材料,讨论了不同形貌Fe3O4前驱体与聚苯乙烯作用的不同效果,及表面活性剂的加入与否对反应的影响。具体研究内容如下：1.利用空气中的氧气作为天然的氧化剂,在较低温度下部分氧化Fe2+,无需氮气保护,简洁快速的制备出具有多种形貌的Fe3O4磁性粒子。制备过程中无需添加其它的稳定剂和氧化剂。我们以pH值、反应温度和反应时间为主要参数设计正交试验,探索反应的最佳条件。对最佳反应条件下制备的产物进行性质表征。结果表明：碱源不同得到的产物形貌各异,以NaOH作为碱源,反应在室温下即可得到产物为八面体状；以氨水作为碱源,反应得到的是类球形纳米粒子；以NaOH和氨水共同作为碱源,得到片状的Fe3O4。该实验不仅为其它类似纳米材料的制备提供了一种简单可行的方法,也为期望通过改变反应物获得不同形貌的纳米材料提供了一个有效的参考。2.在探索得到的最佳反应条件下,分别制备分散性良好的八面体形貌纳米Fe3O4和类球形纳米Fe3O4,反应完全后洗涤至中性,加入适量的油酸钠,通过Fe3O4表面所带羟基与油酸钠的羧基结合形成酯键,我们得到了Fe3O4@油酸核壳结构。对产物性质进行表征的结果显示,油酸钠修饰并未改变Fe3O4原有形貌且仍具有超顺磁性,反应产物中油酸的量占总量的较少。少量油酸的包覆使得Fe3O4表面由原先的亲水转变为疏水。此外,将得到的Fe3O4@油酸分散在有机溶剂中可以形成磁流体且磁响应性和稳定性极好,可广泛应用于磁性流体密封、磁流体选矿等领域。3.将上一章中制备的两种形貌的Fe3O4@油酸纳米材料分散在苯乙烯中,加入引发剂后,苯乙烯在Fe3O4@油酸表面原位聚合,最终得到Fe3O4/PS无机高分子复合材料,后对其性质进行表征并讨论了不同形貌Fe3O4@油酸和表面活性剂对反应的影响。结果表明,类球形形貌Fe3O4@油酸更容易与聚合物形成复合材料,且在没有表面活性剂SDS的情况下也可发生,而对于八面体形貌Fe3O4@油酸,必须在加入SDS的情况下复合才可以发生。更多还原

【Abstract】 In this paper, magnetic nanoparticles have been prepared by precipitation from partial oxidation of Fe2+ using oxygen in the air as natural oxidant, which are superparamagnetic and have high stablity. Besides, through the esterification of hydroxyl on the surface of Fe3O4 and oleate sodium, core-shell Fe3O4@oleic has been synthesized which has excellent hydrophobicity and can form magnetic fluid when dispersed in organic solvent. Furthermore, we have also prepared Fe3O4/Polystyrene (Fe3O4/PS) nanocomposites by micro-emulsion method. The properties and formation mechanisms of the products have also been investigated.The main contents are summarized as follows:Superparamagnetic Fe3O4 nanoparticles were synthesized using a simple and rapid method by precipitation from partial oxidation of Fe2+ under mild conditions, without any additional agent and inert gas. With pH, reaction temperature and time as main parameters, we have designed orthogonal experiments and studied the characterization and property in the optimum conditions.The result shows that products with octaheral, quasi-sphere and plate morphologies are obtained from various alkali source. We not only provided a simple and feasible method for other similar preparation of nanomaterials, but also provided a valid reference for those who want to get different shapes through changing the reactants.Magnetic nanoparticles of octaheral and quasi-sphere morphologies have been dispersed in double-distilled water, then an appropriate amount of sodium oleate is added. Through the esterification of hydroxyl on the surface of Fe3O4 and sodium oleate, we have synthesized Fe3O4@oleic core-shell materials which are superparamagnetic. It is proved that the content of oleic acid is just several percent by TGA. After modification, although thickness of the shell is very thin, we have realized the conversion from the original hydrophilic surface to hrdrophobic surface successfully. Furthermore, the nanoparticles prepared by this experiment can be dispersed in organic solvents to form magnetic fluid which has excellent magnetic response and stability, and has potential applications in the fields of magnetic fluid sealing and mineral porcess.Fe3O4@oleic core-shell nanomaterials are first dispersed in styrene. Then surfactant SDS is added, and in situ polymerization of styrene will happen on the surface of Fe3O4. Finally, Fe3O4 /PS nanocomposites are prepared by this method. Furthermore, the properties are characterized and the influence of morphology and surfcant have been studied.更多还原