Tribological Behavior of Zwitterionic-Polyester Composite Films with Phase-Separated Structures.

Area of Science:

• Materials Science
• Biomedical Engineering
• Tribology

Background:

• Biomedical device lubrication and wear resistance are critical challenges.
• Zwitterionic polymers like poly(sulfobetaine methacrylate) (PSBMA) offer hydration-based superlubricity but lack mechanical strength.
• Poly(ε-caprolactone) (PCL) provides toughness but is hydrophobic, hindering lubrication and biocompatibility.

Purpose of the Study:

• To investigate the tribological behavior of solvent-cast PCL/PSBMA composite films with macrophase separation.
• To understand how varying PCL/PSBMA compositions influence surface properties and friction.
• To evaluate the performance of these composites in both air and water environments.

Main Methods:

• Fabrication of PCL/PSBMA composite films with different compositions (30:70, 50:50, 70:30).
• Tribological testing using reciprocating and rotational motion against PTFE, Si3N4, and GCr15 counterfaces.
• Evaluation under varying loads (0.5-1.0 N) in both air and water.

Main Results:

• The P3Z7 (30% PCL, 70% PSBMA) film achieved ultralow friction (COF reduction >50%) in water, attributed to hydration lubrication.
• The P7Z3 (70% PCL, 30% PSBMA) films exhibited superior stability in air.
• Macrophase separation in the composites critically influenced surface homogeneity and tribological behavior.

Conclusions:

• PCL/PSBMA composites with controlled macrophase separation can be tailored for specific lubrication and stability requirements.
• The P3Z7 composition is promising for aqueous biomedical applications requiring ultralow friction.
• The P7Z3 composition offers enhanced stability in dry environments, potentially for other biomedical applications.