Objective In order to solve the problems such as too stable traditional foam and difficulty in defoaming.

Method Using N-dodecyl-1,3-propanediamine and temperature and salt tolerant anionic surfactant to prepare a CO₂ responsive temperature and salt tolerance composite foam system, and uses molecular simulation to explore the stability and response mechanism of the composite foam.

Results Results show that N-dodecyl-1,3-propanediamine has good protonation and salt tolerance properties. However, its temperature tolerance is poor, and it does not have response performance. After compounding with sodium dodecyl sulfate (SDS) and sodium dodecyl sulfate, the foaming speed at high temperature is increased by 40%, the foam duration is 3.17 times longer than that before compounding, the temperature resistance is significantly improved, and the foam is defoamed rapidly within a short period after passing CO₂. Molecular simulation studies reveal that the S atomic groups contained in SDS will combine with the positively charged N atomic groups in C₁₂N(CH₃)N(CH₃)₂ and lose surface activity, resulting in poor stability of the foam, which is also responsible for the responsive defoaming.

Conclusion The composite system has good temperature and salt resistance and responsiveness, and can realize responsive defoaming after foam drainage and gas production in harsh environments which has broad application prospects.