Dale Phillip J, Kijlstra Johan, Vincent Brian
School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS United Kingdom.
Langmuir. 2005 Dec 20;21(26):12250-6. doi: 10.1021/la052141q.
The temperature stability of aqueous dispersions of hydrophobic monodisperse silica particles stabilized with nonionic surfactants has been investigated. Adsorption isotherms in conjunction with surface tension measurements showed that the surfactant formed a monolayer on the surface of the particles, where the adsorbed amount depended on the molecular weight of the ethylene oxide headgroup. The temperature stability of these dispersions has been measured by a standard turbidimetric technique and visual observations in terms of their critical flocculation temperature (CFT). Parameters controlling the CFT of the individual dispersions stabilized with a monolayer of surfactant include the thickness of the steric layer, the particle size, and the volume fraction of the particles. Calculations show that the van der Waals attraction between the particles with adsorbed polymer layers increases as the temperature of the dispersion increases, and this largely accounts for the observed CFT behavior.
研究了用非离子表面活性剂稳定的疏水性单分散二氧化硅颗粒水分散体的温度稳定性。结合表面张力测量的吸附等温线表明，表面活性剂在颗粒表面形成了单层，吸附量取决于环氧乙烷头基的分子量。这些分散体的温度稳定性已通过标准比浊法技术并根据其临界絮凝温度（CFT）进行了目视观察来测量。控制由单层表面活性剂稳定的各个分散体的CFT的参数包括空间层的厚度、颗粒大小和颗粒的体积分数。计算表明，随着分散体温度升高，带有吸附聚合物层的颗粒之间的范德华吸引力增加，这在很大程度上解释了观察到的CFT行为。
