Micelle Aggregation Behavior Of Gemini Surfactants In Solution

Fracturing fluid is an important working fluid widely used in oil exploitation,and surfactant is an important additive for fracturing fluid.At present,finding a high temperature,high pressure,environmentally friendly fracturing fluid has always been a hot topic in the field of oil exploitation.Water-based fracturing fluid is currently the most used fracturing fluid,while traditional water-based fracturing fluids have problems such as high construction cost,poor high temperature resistance and environmental pollution.Therefore,it is especially useful to find a new type of clean fracturing fluid.Urgent,long-chain gemini surfactants are an important additive for water-based cleaning fracturing fluids.In this paper,the mesoscopic simulation of two typical long-chain gemini surfactants were carried out by dissipative particle dynamics method.The two gemini surfactants were coarsely divided according to the principle of equal volume and the structural model was constructed.The solubility parameters of the system were determined according to the mixing energy.The micelle aggregation process of gemini surfactant in aqueous solution and oil-water mixed solution was calculated.The influence of additive ethanol and hydrophobic chain length on micelle aggregation behavior was analyzed.The effect of gemini surfactant on CMC and interfacial tension was investigated.The main findings of this paper are as follows:(1)The aggregation morphology of gemini surfactants will change with increasing concentration.When the concentration is low,spherical micelles are formed;as the concentration increases,gemini surfactants will aggregate to form worm-like micelles or even layered micelles.These results are completely consistent with previous experimental reports.(2)The study found that the additive ethanol will have a certain impact on the aggregation morphology of gemini surfactants.The addition of ethanol hinders the aggregation behavior of the gemini surfactant and hinders the formation of large size micelles.The mechanism may be related to the fact that the addition of ethanol destroys the ordered structure of water molecules around the hydrophobic groups in the solution,and the calculation of the average number of micelle aggregates further confirms this mechanism.It is also found that the length of the hydrophobic chain has a certain influence on the micelle aggregation behavior of the gemini surfactant.The longer the hydrophobic chain length,the easier it is to form large and tight spherical clusters.(3)We simulated the micelle aggregation behavior of gemini surfactant in oil-water mixed solution system,analyzed the oil-water interfacial tension and the critical micelle concentration of surfactant,and obtained the results consistent with the experiment.