Toughening Self-Healing Elastomers with Chain Mobility.

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Soft elastomers are vital for modern devices, but their operational lifetimes are limited by susceptibility to damage.
• Enhancing fracture toughness and self-healing capabilities is critical for improving the durability and longevity of these materials.

Purpose of the Study:

• To investigate methods for enhancing fracture toughness and self-healing in carboxylated-functionalized polyurethane.
• To understand the role of polymer chain mobility in achieving these improved material properties.

Main Methods:

• Incorporation of plasticizers and thermal treatment to tune polymer chain mobilities.
• Fracture toughness testing, including double cantilever beam tests, to evaluate material performance.
• Varying temperatures (80-120°C) and plasticizer concentrations (optimal at 3 wt.%) to assess property enhancements.

Main Results:

• Increasing temperature from 80 to 120°C significantly boosted the recovered work of fracture (2.86 to 123.7 MJ m⁻³).
• Optimal plasticizer (3 wt.%) and temperature (40°C) conditions improved fracture toughness from 16.3 to 19.9 and 25.6 kJ m⁻², respectively.
• Carboxyl hydrogen bonds and chain mobility were identified as key mechanisms for energy dissipation and stress redistribution, leading to crack blunting.

Conclusions:

• Tuning polymer chain mobility is an effective strategy to simultaneously enhance fracture toughness and self-healing in soft elastomers.
• These improvements contribute to the prevention of damage and facilitate better recovery, extending the functional lifetime of soft devices.
• Understanding fracture mechanics at healed interfaces is crucial for predicting material behavior and failure prevention in self-healing elastomers.