School of Chemical and Biological Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea.
ACS Nano. 2015 May 26;9(5):4939-49. doi: 10.1021/nn5068495. Epub 2015 Apr 8.
The double-shell SiO2/TiO2 hollow nanoparticles (DS HNPs) are successfully fabricated and adopted as dispersing materials for electrorheological (ER) fluids to investigate an influence of shell structure on ER properties. The DS HNPs-based ER fluid exhibits outstanding ER performance which is 4.1-fold higher compared to that of single shell SiO2/TiO2 hollow nanoparticles (SS HNPs)-based ER fluid. The significantly improved ER property of DS HNPs-based ER fluid is ascribed to the enhanced interfacial polarization. In addition, the ER activities of DS HNPs-based ER fluids are examined depending on the particle diameter. The yield stress of DS HNPs-based ER fluids increases up to 302.4 kPa under an electric field of 3 kV mm(-1) by reducing the particle size, which is remarkable performance enough to promise sufficient probability for practical and industrial applications. The enhanced ER performance of the smaller DS HNPs is attributed to the increased surface area of large pores (30-35 nm) within the shells, resulting in a large achievable polarizability determined by dielectric constants. Furthermore, the antisedimentation property is analyzed in order to offer an additional insight into the effect of particle size on the ER fluids.
双层 SiO2/TiO2 空心纳米粒子（DS HNPs）被成功制备，并被用作电流变（ER）流体的分散材料，以研究壳层结构对 ER 性能的影响。基于 DS HNPs 的 ER 流体表现出出色的 ER 性能，比基于单壳层 SiO2/TiO2 空心纳米粒子（SS HNPs）的 ER 流体高 4.1 倍。DS HNPs 基 ER 流体具有显著改善的 ER 性能归因于增强的界面极化。此外，还根据颗粒直径检查了基于 DS HNPs 的 ER 流体的 ER 活性。通过减小粒径，基于 DS HNPs 的 ER 流体在 3 kV mm(-1) 的电场下的屈服应力增加到 302.4 kPa，这是足够显著的性能，足以保证在实际和工业应用中有足够的可能性。较小的 DS HNPs 的增强的 ER 性能归因于壳内大孔（30-35nm）的表面积增加，从而导致由介电常数决定的大可极化率。此外，还分析了抗沉降性能，以便更深入地了解粒径对 ER 流体的影响。
