摘要
Owing to its ability to be reversibly switched on-demand, pH-responsive surfactants show promising applications in agriculture, detergents, and oil recovery. However, maintaining the stability of pH-responsive emulsions under harsh shear and salinity conditions remains challenging. To address this issue, we developed novel Pickering emulsions with both pH-responsiveness and high environmental robustness stabilized by a series of synthesized pH-responsive surfactants, (CH 3 ) x NCOONa (x = 2, 4, 6), and investigated their interfacial behavior and emulsion stability using experiments and dissipative particle dynamics (DPD) simulations. Among them, (CH 3 ) 4 NCOONa showed a better surface activity and pH responsiveness. Pickering emulsion composed of (CH 3 ) 4 NCOONa and SiO 2 nanoparticles was found to exhibit excellent viscosity response with 26 times decrease from 204.1 to 7.8 mPa·s when pH increased from 7.3 ± 0.5 to 9.2 ± 0.5. To further enhance the shear and salinity resistance of Pickering emulsions, three green polymers were introduced into the system. Among the tested polymers, chitosan most effectively enhanced the static viscosity from 204.1 to 550.2 mPa·s and kept stable at a high shear rate of 60 s −1 at pH = 7.3 ± 0.5, whereas its viscosity slightly changed at pH = 9.2 ± 0.5, indicating that the chitosan synergistic-stabilized Pickering emulsion showed a good pH response. Notably, the chitosan stabilized Pickering emulsion also remained stable in 4 wt% simulated seawater. Additionally, the stability mechanism of Pickering emulsions with pH-responsive surfactants was demonstrated by DPD, revealing denser interfacial packing of zwitterionic DEU z over anionic DEU a , consistent with experimental stability trends. These findings demonstrate a novel strategy for constructing environmentally responsive and mechanically robust emulsions, providing both mechanistic understanding and practical pathways for demanding applications in harsh field conditions.
危险品化学品经营许可证（带存储）