题目：The key to surfactant-free microemulsion demulsification: CO2 promotes the transfer of amphiphilic solvent to aqueous phase
In recent years, research on surfactant-free microemulsion (SFME) has given us new insight into the field of microemulsion. Here, we report a SFME with CO2 responsiveness prepared by mixing 1-dodecanol (oil phase), aqueous phase and N,N-dimethylethanolamine (DMEA, amphiphilic solvent) at appropriate proportion. The proportion of the three components used to prepare SFME was obtained by analyzing the ternary phase diagram of DMEA, 1-dodecanol and water. Meanwhile, the microstructure transition characteristics of SFME from oil-in-water (O/W) to bicontinuous phase (B.C) to water-in-oil (W/O) was characterized by electrical conductivity and UV-Vis spectroscopy. In addition, the CO2 response behavior of W/O microemulsion has been studied deeply. We found that a significant demulsification phenomenon when CO2 was introduced into this SFME system. By measuring the concentration of DMEA in dodecanol after demulsification, the demulsification mechanism of SFME can be confirmed: The introduction of CO2 causes the protonation of DMEA, and this process makes the amphiphilic solvent more soluble in the aqueous phase, which results in destabilization of this ternary system. Eventually, with the continuous introduction of CO2, the separation of the oil and water phases of SFME occurs.
刘东芳，博士，硕士导师。主要研究方向为表面活性剂的自组装、乳液、微乳液、纳米乳液的制备及应用。同时对于刺激响应表面活性剂及其在改变油水界面性质领域进行了较为深入的研究工作。先后在Langmuir、Soft Matter、Energy & Fuels等期刊发表SCI论文10余篇。