SiO2 shell formation mechanism and enlargement on hydrophobized nanoparticles via a reverse microemulsion process
SiO2 shell formation mechanism and enlargement on hydrophobized nanoparticles via a reverse microemulsion process
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DOI：
10.1007/s10971-017-4479-8
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发表时间：
2017-10-01
影响因子：
2.5
通讯作者：
Inumaru, Kei
中科院分区：
文献类型：
--
作者：
Katagiri, Kiyofumi;Narahara, Masaya;Inumaru, Kei
采用动态光散射法研究了反相微乳液法制备油酸酯改性无机纳米粒子表面SiO2壳层的形成机理。加入非离子表面活性剂Igepal CO-520和氨水后流体动力学直径的变化表明，在无机纳米颗粒的表面发生了表面活性剂交换和水层形成。水层作为SiO2壳形成的反应位点。所提出的机制解释了如何获得具有单个核的核-壳颗粒。此外，通过该方法获得的最大核-壳粒径的限制也可以通过所提出的机制来解释。SiO2壳生长进一步研究考虑这种机制。观察到Igepal CO-520和氨水的增量添加促进了Fe 3 O 4纳米颗粒周围的反相微乳液层的膨胀和SiO2壳的继续生长。还可以通过斯托伯工艺实现SiO2壳的进一步生长。核-壳颗粒可以生长到超过100 nm的直径，同时保持窄的粒度分布，并且始终获得单核结构。本文提出的方法提供了一种制备各种核-壳粒子的方法，这些核-壳粒子包括疏水化无机纳米粒子和SiO2壳，具有生物医学实际应用的潜力。
The formation mechanism of SiO2 shells on oleate-modified inorganic nanoparticles by a reverse microemulsion method was investigated by dynamic light scattering measurements. Changes in the hydrodynamic diameter upon addition of the nonionic surfactant, Igepal CO-520, and ammonia water revealed that the surfactant-exchange and aqueous layer formation took place at the surface of the inorganic nanoparticles. The aqueous layer functioned as a reaction site for SiO2 shell formation. The proposed mechanism explains how core-shell particles having a single core are obtained. Additionally, the limitation of a maximum core-shell particle size obtained by this process can also be explained by the proposed mechanism. SiO2 shell growth was further examined by consideration of this mechanism. Incremental addition of Igepal CO-520 and ammonia was observed to facilitate the expansion of a reverse microemulsion layer surrounding the Fe3O4 nanoparticles and the continuing growth of the SiO2 shell. Further growth of the SiO2 shell can also be achieved by the Stober process. The core-shell particles can grow to diameters in excess of 100 nm while maintaining narrow particle size distributions and a single-core structure is obtained throughout. The approach presented here offers a way to fabricate various core-shell particles comprising hydrophobized inorganic nanoparticles and SiO2 shells, which have potential for biomedical practical applications.