(669a) Impact of Molecular Structure on Surface and Thermal Properties of Amido-Amine Cationic Gemini Surfactants

One of the great challenges of surfactant flooding is the stability of surfactants in harsh reservoir conditions such as high salinity and high temperature. The less stable surfactants easily degrade under these condition and loss their property of lowering the interfacial tension between oil and water. In order to overcome the drawbacks of surfactant flooding, a variety of gemini cationic surfactants were synthesized. The structures of the synthesized surfactants were confirmed using NMR (¹H and ¹³ C), FTIR and elemental analysis. Thermogravimetric analysis was used to identify the short-term thermal stability and structure analysis technique was used to investigate the long-term thermal stability of the synthesized surfactants. Pendant drop technique was used to measure the surface properties of the surfactant. The synthesized surfactants exhibited excellent short-term and long-term thermal stabilities and no changes in structure were detected. The critical micelle concentration and the corresponding surface tension of the surfactants showed excellent surface properties and these values are comparable with the commercially available surfactants. The critical micelle concentration of gemini surfactants was decreased with increasing length of the spacer. Similarly, the critical micelle concentration and corresponding surface tension decreased by increasing tail length. The rigidity and spacer conformation of the spacer double bond also affect the surface properties. The surface area per molecules decreased with increasing tail length, spacer flexibility, and spacer length.