Abstract The influence of water-soluble polyethylene glycols PEG200 on the properties of sodium bis(2-ethylhexyl)-sulfosuccinate (AOT) water-in-isooctane microemulsions has been investigated by conductivity measurement and isothermal titration microcalorimetry (ITC). The percolation temperatures (Tp), the thermodynamic properties of droplet aggregation and the interaction enthalpy (−ΔHφ) between droplets for AOT/water/PEG200/isooctane with different PEG concentrations and a fixed molar ratio of water to surfactant ω = 22.2 were determined. Based on a two-stage thermodynamic approach of the percolation, we obtained the fusion enthalpy (ΔHf0) of the close contact droplets by a combination of the droplet aggregation enthalpy (ΔHag0) and −ΔHφ. It was found that both (−ΔHφ) and (ΔHf0) varied with the concentration of PEG200 (cPEG) and had the extreme value at cPEG = 25 g L−1. This phenomenon was interpreted by the variation of interface rigidity due to the varied distributions of added PEG200 between the water pool and the surfactant interface.

中文翻译：

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聚乙二醇对AOT/水/异辛烷微乳相互作用及稳定性的影响

摘要 通过电导率测量和等温滴定微量热法 (ITC) 研究了水溶性聚乙二醇 PEG200 对双(2-乙基己基)-磺基琥珀酸钠 (AOT) 异辛烷包水微乳液性质的影响。确定了具有不同 PEG 浓度和固定的水与表面活性剂摩尔比 ω = 22.2 的 AOT/水/PEG200/异辛烷的渗透温度 (Tp)、液滴聚集的热力学性质和液滴之间的相互作用焓 (-ΔHφ)。基于渗透的两阶段热力学方法，我们通过液滴聚集焓（ΔHag0）和-ΔHφ的组合获得了紧密接触液滴的融合焓（ΔHf0）。发现 (-ΔHφ) 和 (ΔHf0) 均随 PEG200 (cPEG) 的浓度而变化，并且在 cPEG = 25 g L-1 时具有极值。由于水池和表面活性剂界面之间添加的 PEG200 分布不同，因此可以通过界面刚度的变化来解释这种现象。