Toughening Elastomer while Lowering Hysteresis Using Peptide Cross-Linkers.

Area of Science:

• Polymer Science
• Materials Science
• Biomaterials

Background:

• Elastomers often exhibit high hysteresis when toughened.
• Sacrificial bonds can improve toughness but increase hysteresis.
• A trade-off exists between elastomer toughness and hysteresis.

Purpose of the Study:

• To synthesize peptide-cross-linked elastomers with enhanced toughness and low hysteresis.
• To investigate the mechanical, adhesive, and fatigue properties of these novel elastomers.
• To demonstrate the utility of these elastomers in a composite hydrogel strain sensor.

Main Methods:

• Synthesis of poly(benzyl acrylate) elastomers using peptide cross-linkers.
• Characterization of mechanical properties including toughness, ductility, and fatigue resistance.
• Evaluation of adhesive properties, particularly underwater adhesion stability.
• Fabrication and testing of a composite hydrogel strain sensor.

Main Results:

• Peptide-cross-linked elastomers exhibited significantly enhanced toughness and lowered hysteresis.
• The material showed high ductility (4700% break strain), crack-insensitivity (1.25 × 10⁴ J m⁻² fracture toughness), and fatigue resistance (9.27 × 10² J m⁻² fatigue threshold).
• Excellent adhesion strength (up to 5.50 × 10² kPa) and long-term underwater stability were achieved.
• A composite hydrogel strain sensor successfully monitored human motion in air and underwater.

Conclusions:

• Poly(γ-benzyl-l-glutamate)-based peptide cross-linkers effectively overcome the toughness-hysteresis trade-off in elastomers.
• The resulting elastomers possess a unique combination of high toughness, low hysteresis, high ductility, and robust adhesion.
• These advanced elastomers are promising for applications in flexible electronics, sensors, and underwater devices.