反胶束体系中Fe_3O_4/SiO_2核壳结构纳米粒子的制备和表征

Synthesis and characterization of Fe_3O_4/SiO_2 core-shell nanoparticles in reverse micelles

在反胶束体系中制备Fe3O4/SiO2核壳结构纳米粒子,并利用透射电子显微镜表征颗粒的结构和形貌.首先,在水体系中采用共沉淀法制备平均粒径为13nm的Fe3O4纳米粒子,并用有机小分子柠檬酸对其进行表面修饰,加入氨水后形成稳定的Fe3O4胶体溶液.然后,将此胶体溶液作为水相滴加到Triton X-100/环己烷/正丁醇的表面活性剂/油相/助表面活性剂溶液体系中,搅拌后形成稳定的油包水反胶束体系.在反胶束内以氨水为催化剂,使正硅酸乙酯水解,从而获得SiO2包覆的Fe3O4核壳结构纳米粒子.实验结果表明,改变水和表面活性剂Triton X-100的浓度比ω,可以达到调控核壳结构纳米粒子形貌的目的.当ω=9时,可获得尺寸均匀、平均粒径约为100nm的Fe3O4/SiO2核壳结构纳米粒子.

Fe3O4/SiO2 core-shell nanoparticles are synthesized in reverse micelles and analyzed by transmission electron microscopy. Firstly, Fe3O4 nanoparticles with a mean diameter of 13 nm are prepared by a co-precipitation method and then modified by citric acid. With the addition of ammonia, a stable aqueous-base magnetic fluid is obtained. Subsequently, the magnetic fluid is added into a Triton X-100/cyclohexane/butanol organ solution and stirred to form stable reverse micelles. Using ammonia as a catalyst, tetraethyl orthosilicate （TEOS） is hydrolyzed in the reverse micelles to form Fe3O4/SiO2 core-shell nanoparticles. The experimental results show that the shape of the products can be varied by changing the concentration ratio of aqueous to Triton X-100, ω. When ω =9,the uniform Fe3O4/SiO2 core-shell nanoparticles with a mean diameter of 100 nm are obtained.