The conventional foam drainage technology needs to be defoamed, which is not convenient for its popularization and application. In view of this problem, from the point of molecular design, a temperature-responsive surfactant was designed and synthesized. In the synthetic process, polyoxyethylene alkyl ether carboxylic acid, diethanolamine and sodium chloroacetate were used as raw materials. First, polyoxyethylene alkyl ether carboxylic acid reacted with diethanolamine to generate a tertiary amine with hydroxyl catalyzed by sulfoxide chloride, and the intermediate product then reacted with sodium chloroacetate by the quaternary amine reaction to afford the target temperature-responsive surfactant. The foaming agent can achieve conformational transformation in the temperature range of 20 °C to 120 °C, resulting in the structural change of the self-assembly and regulating the stability of the foam, which makes the formed foam burst rapidly at low temperatures and be super-stable at high temperatures. The indoor evaluations show that the foaming height of the foaming agent is basically unchanged at the same temperature after 4 temperature-changing cycles, and the temperature-controlled defoaming rate reaches 90%, indicating that it has the intelligent temperature response switching performance of "high-temperature defoaming, low-temperature defoaming". Its preparation process is simple, low-cost, and environmentally friendly. It is expected to be popularized and applied in the field of gas fields, expand the application scope of foam drainage technology, reduce the cost of foam drainage, and help the efficient development of gas fields.
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