Temperature and pH responsive behavior of wormlike micelles formed by a long chain Gemini-like surfactant

A Gemini-like surfactant is formed by connecting short chain dibasic acid and long chain tertiary amine in the molar ratio of 1:2 through the non-covalent action of electrostatic attraction, and does not need complicated synthesis. Due to the tertiary amine group in the Gemini-like surfactant, it exhibits pH-responsive properties. However, in the research, we were pleasantly surprised to find that the Gemini-like surfactants also showed temperature response characteristics. With the increase of temperature, the viscosity of the system increases rapidly, and it is resistant to high temperatures. At 60°C, the zero-shear viscosity of the system at the concertation of 300 mM can reach an extremely high value of 11967.73 Pa·s, which was higher than most of wormlike micelles formed by the conventional covalently linked oligomeric counterparts. The reason for this phenomenon may be that as the temperature increases, the hydrogen bonds in the system are destroyed, resulting in the reduction of the repulsive force between molecules and the shortening of the intermolecular distance, which makes the micelles more entangled closely.