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A novel branched polyether surfactant (TPE) was prepared by anion polymerization with different proportions of propylene oxide (PO) and ethylene oxide (EO) using 1,1,2,2‐tetrakis(4‐hydroxyphenyl)ethane as a core. The structures and average molecular weight (Mn) of the TPE were characterized by 1H NMR and GPC. The cloud point was determined by turbidimetry in the presence of inorganic salts. Inorganic salts decreased the cloud point of TPE polyether in the following order: Na2CO3 > Na2SO4 > NaCl > CaCl2 > MgCl2. The effects of inorganic salts (NaCl, MgCl2, CaCl2, and NaSCN) and temperature on the surface activity of TPE in aqueous solution were investigated by surface tension measurements. The surface activity parameters and the thermodynamic parameters were calculated from surface tension data. Similar to the effect of increasing temperature, the salting‐out inorganic salts such as NaCl, MgCl2, and CaCl2 favor the micellization and increase the maximum surface excess concentration, while the salting‐in NaSCN has the opposite effect. The influence of NaCl on the morphology of micelles was investigated by TEM. The micellization is entropy‐driven at low temperature and enthalpy‐driven at higher temperature. The TPE polyether has large surface activity and can be used as a demulsifier to break up crude oil emulsions.

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