A dual-responsive microemulsion with macroscale superlubricity and largely switchable friction

Area of Science:

• Materials Science
• Tribology
• Colloid and Surface Chemistry

Background:

• Stimuli-responsive microemulsions (MEMs) are used in various industrial applications.
• Achieving controllable friction states and macroscale superlubricity in MEMs remains a challenge.
• Traditional liquid superlubricants lack precise friction control crucial for smart devices.

Purpose of the Study:

• To develop a novel stimuli-responsive microemulsion (MEM) with switchable friction states.
• To achieve macroscale superlubricity and controllable friction for metallic materials.
• To explore applications in smart devices and advanced materials science.

Main Methods:

• Formulation of a thermo- and magneto-responsive MEM using n-hexane, water, DDACe surfactant, and ethylene glycol.
• Investigation of friction properties across a broad temperature range (-30 to 20 °C).
• Analysis of the MEM-emulsion (EM) transition for friction switching.

Main Results:

• A novel thermo- and magneto-responsive MEM was created, enabling superlubrication for metallic materials.
• The MEM demonstrated a 25-fold switchable coefficient of friction (CoF) via a thermally reversible MEM-EM transition.
• Effective anti-freezing lubrication was observed down to -60 °C, alongside high colloidal stability and magnetic migration control.

Conclusions:

• A novel smart MEM exhibiting switchable superlubricity and anti-freezing properties was successfully developed.
• The MEM's ability to control friction states opens avenues for advanced instrumentation and smart device fabrication.
• The facile preparation, stability, and magnetic responsiveness suggest broad applicability in materials science.