Marangoni spreading time evolution and synergism in binary surfactant mixtures

Area of Science:

• Fluid dynamics
• Surface chemistry
• Interfacial phenomena

Background:

• Marangoni spreading, driven by surface tension gradients, is crucial in various applications.
• Previous studies focused on single surfactants; binary mixtures introduce complex interactions.
• Surface tension synergism in binary surfactants may enhance spreading dynamics.

Purpose of the Study:

• Investigate Marangoni spreading in binary surfactant mixtures.
• Explore the concept of "Marangoni synergism" arising from binary surfactant interactions.
• Determine the influence of thermodynamic and kinetic properties on spreading dynamics.

Main Methods:

• Performed tracer experiments to observe surfactant front motion.
• Developed computational models coupling fluid dynamics and adsorption.
• Utilized binary surfactant pairs with varied interaction strengths.

Main Results:

• Confirmed the existence of Marangoni synergism in binary surfactant systems.
• Stronger surfactant attraction enhanced both surface tension reduction and Marangoni spreading.
• Thermodynamic factors controlled early spreading, while adsorption/desorption kinetics influenced later stages.

Conclusions:

• Marangoni synergism is a distinct phenomenon from surface tension synergism.
• Both thermodynamic and kinetic properties are critical for understanding binary surfactant spreading.
• Adsorption kinetics play a key role in the occurrence of Marangoni synergism over time.