疏水二氧化硅
化学工程
消泡剂
聚二甲基硅氧烷
疏水
材料科学
二氧化硅
纳米颗粒
分散性
气相二氧化硅
高分子化学
化学
分散剂
复合材料
纳米技术
色散(光学)
工程类
物理
光学
作者
Linan Wang,Huanmin Wang,Mingming Rong,Wei Li,Ning Li,Peisong Liu,Xiaohong Li,Zhijun Zhang
标识
DOI:10.1016/j.jcis.2024.05.111
摘要
Hydrophobic nano silica powder is a kind of important synergist to silicone defoaming agents. The large pore volume and branched chain conformation of silica nanoparticles present superior effects on defoaming properties. However, silica nanoparticles synthesized by liquid phase easily aggregate and pore collapse because of their high surface activity and polarity, leading to poorer dispersity and limited practicability. In this paper, a novel hydrophobic silica with a hyperbranched structure was designed through in-situ modifying method with hexamethyldisilazane (HMDS) and polydimethylsiloxane (PDMS) in the liquid phase. The trimethylsilanol generated by HMDS hydrolysis reacts quickly with the highly active hydroxyl groups on the silica, causing the surface properties of the nanoparticles to transform from polar to non-polar properties. The steric hindrance of the trimethyl silicon and the reduction of the surface polarity effectively prevent silica pores from collapsing and maintain the macropore structures to realize the hyperbranched silica. At the same time, the −Si (CH3)2- from PDMS endowed the hyperbranched silica with excellent hydrophobicity. When applied in the defoaming agent, the hydrophobicity of silica contributes to dewetting the foams, and the hyperbranched spatial structures play an enhanced needling effect. Therefore, this hydrophobic hyperbranched silica exhibited a surprising defoaming effect, which significantly reduced the defoaming time from 464.4 s to less than 2 s, superior to commercial defoaming silica (155.3 s). The defoaming efficiency reached 100 % within 2 s of the end of the shaking, and the defoamer antifoaming ability was improved to reach 27.5 min, which was 77 % higher than that of commercial defoamer.
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