【摘要】 采用一种新的相转移法制备了双层包裹的Fe3O4正己烷磁流体.首先,以油酸钠作为表面改性剂,对化学共沉淀制备的Fe3O4纳米颗粒进行双层包裹,制备了稳定的水基磁流体,在此基础上,通过加入乙酸(CH3COOH)将亲水颗粒转变为亲油颗粒,并用萃取的方法将亲油颗粒成功转移到正己烷相.傅里叶变换红外光谱(FTIR)表明,通过调整pH值可以将双层包裹的磁性颗粒外层带有的亲水基团油酸根R—COO-转变为亲油的R—COOH,从而使得包裹的颗粒既可溶于极性载液也可溶于非极性载液.利用X射线衍射仪(XRD)、振动样品强磁计(VSM)和透射电子显微镜(TEM)对Fe3O4颗粒的形貌、组成及磁流体的性质进行了表征.结果表明,利用这种新的相转移法可以保证颗粒在单分散下充分包裹并避免团聚.制备的正己烷磁流体稳定性好,长期放置未发生分层现象.通过蒸发正己烷,可以得到不同固含量的磁流体并可以将其与其它油基载液互溶,从而得到不同载液的Fe3O4油基磁流体.更多还原

【Abstract】 A novel and facile phase-transform method has been presented for the preparation of double-coated Fe3O4 hexane ferrofluid.Firstly,the double-coated Fe3O4 nanoparticles were synthesized via chemical coprecipitation and excess sodium oleate were used as surfactant to yield a stable water-based magnetic fluid.Based on this,hydrophilic Fe3O4 nanoparticles were transformed into hydrophobic ones which were extracted to hexane by adding acetic acid.Fourier transform infrared(FTIR) spectra show that —COO-at the outer layer of Fe3O4 nanoparticles transforms into —COOH at proper pH value adjusted by acetic acid,which makes Fe3O4 nanoparticles hydrophobic and dispersive in polar or nonpolar carrier liquid.X-Ray diffractometer(XRD),vibrating sample magnetometer(VSM) and transmission electron microscope(TEM) were also used to characterize the magnetic nanopartieles and the ferrofluid.Our method ensures that Fe3O4 nanoparticles are coated compactly and mono-dispersive state without any agglomeration,which makes the thus obtained hexane ferrofluid stable and less delamination after several months.The ferrofluid with different solid content and dispersed in other oil-based carriers can be obtained through evaporating n-hexane.更多还原