范德瓦尔斯力
哈梅克常数
纳米颗粒
乳状液
化学工程
皮克林乳液
分散性
油滴
材料科学
粒子(生态学)
纳米技术
化学
有机化学
高分子化学
分子
工程类
海洋学
范德瓦尔斯半径
地质学
作者
Jing Wang,Yajuan Sun,Mingying Yu,Xihua Lu,Sridhar Komarneni,Cheng Yang
标识
DOI:10.1016/j.jcis.2021.01.011
摘要
Highly hydrophilic nanoparticles are generally considered not suitable for stabilizing Pickering emulsions, since they could not be effectively wetted by the oil phase at the water-oil interface. However, highly hydrophilic nanoparticles with good dispersity are possibly absorbed and packed onto the surface of the oil droplets in water via the van der Waals attraction between the nanoparticles and the oil droplets. Hence, a novel “van der Waals emulsion” should be possible to be stabilized by highly hydrophilic nanoparticles. Oil-in-water emulsions solely stabilized by pristine TiO2 nanoparticles (i.e., TiO2 without any modification or additives) were prepared. The emulsification behavior under varying pH value, oil fraction, particle content and temperature of the emulsion were explored. Composite wax-based beads which encapsulated chemical sunscreen and was coated by TiO2 nanoparticles, was also fabricated using the obtained emulsion as the templates. The emulsions displayed the highest stability near the isoelectric points of the TiO2 nanoparticles, which was attributed to the van der Waals attraction between TiO2 nanoparticles and oil droplets. Such mechanism was supported by a theoretical analysis based on calculation of the Hamaker constants and experimental evidences. Therefore, this work presents a simple, general and green method for preparing particle-stabilized emulsions.
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