Spherical-to-wormlike micelle transition in a pseudogemini surfactant system with two types of effective pH-responsive groups

• The pseudogemini surfactant system is pH-responsive.
• The two types of pH-responsive groups in this pseudogemini surfactant system both worked for the micelle transition.
• Viscosity of the pseudogemini surfactant system can be promptly regulated by pH.
• The low-high-low viscosity variation can be reversibly switched at least 3 cycles of pH regulation.

A novel pseudogemini surfactant system, which has two types of pH-responsive groups in the connection of the alkyl chain and the spacer, has been developed and investigated by adjusting pH. These two types of pH-responsive groups both worked for the micelle transition because they had different ionization degrees and electrostatic attraction forces with the aid of pH variation. The system could be promptly switched between low viscosity fluid and high viscoelastic solution. Besides, the pH-responsive ability was studied by the steady and dynamic rheological measurements, which is effective after several cycles of pH adjusting with the almost invariable magnitude level of viscosity. The transition between spherical micelle and wormlike micelle for the surfactant system at different pH values could be further confirmed by dynamic light scattering and cryogenic transmission electron microscopy characterization.

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