无溶剂Fe3O4纳米流体的制备及表征

采用共沉淀法合成Fe3O4纳米粒子, 将含有硅氧烷基的离子型改性剂二甲基十八烷基氯化铵与Fe3O4纳米粒子进行接枝反应, 再用脂肪醇聚氧乙烯醚磺酸盐的长链阴离子交换Cl-, 在Fe3O4纳米粒子表面生成具有阴、 阳离子双电层结构的表面处理层, 得到无溶剂Fe3O4纳米流体. 研究结果表明, 在Fe3O4纳米粒子表面成功接枝了有机物长链, 改性的Fe3O4纳米粒子呈单分散分布, 其损耗剪切模量G″明显大于储能剪切模量G', 具有明显的流体行为, 在室温下即可流动.

Preparation and Characterization of Solvent-free Fe3O4 Nanofluids

The surfactant was used to functionalize the nanoparticles to prepare solvent-free nanofluids.To prevent Fe3O4 nanoparticles from agglomerating and improve the dispersion of Fe3O4 nanoparticles,the solvent-free Fe3O4 nanofluids were synthesized through surface modification.Magnetic Fe3O4 nanoparticles were firstly prepared by chemical co-precipitation method.Then graft the quaternary ammonium salt(CH3O)3Si(CH2)3N+(CH3)2(C18H37)Cl-,which has silanol groups,on Fe3O4 nanoparticles with hydroxyl groups.Finally,the chloridion was replaced with the anion C9H19—C6H4(OCH2CH2)20O(CH2)3SO3 through an ion-exchang process.An organic layer was formed on the surface of Fe3O4 nanoparticles,and made the Fe3O4 nanoparticles from black powder to brown fluid(at room temperature).The solvent-free Fe3O4 nanofluids were characterized by X-ray diffraction,Fourier transform infrared spectrum,differential scanning calorimetry,thermogravimetric analysis,transmission electron microscopy and rheometer.The Fe3O4 nanoparticles were monodispersed in solvent-free nanofluids,and the content of Fe3O4 nanoparticles in the nanofluids proved to be about 12%.The loss shear modulus G″ was higher than the storage shear modulus G′.