Biomimetic Water-Responsive Self-Healing Epoxy with Tunable Properties

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Dynamic cross-linking networks are typically weaker than permanent covalent networks, posing challenges for creating stiff, self-healing polymers.
• Nature-inspired designs, such as the sea cucumber's adaptive properties, offer valuable insights for developing advanced materials.

Purpose of the Study:

• To design a water-responsive, self-healing polymer system combining reversible and permanent covalent networks.
• To achieve a material with mechanical properties comparable to classic thermosets while retaining self-healing capabilities.

Main Methods:

• Synthesized a dual cross-linked polymer system using poly(propylene glycol), boroxine, and epoxy.
• Investigated the material's self-healing, mechanical properties (tensile modulus and stress), water responsiveness, adhesion, and potential for sensor applications.

Main Results:

• The polymer system exhibits a room-temperature tensile modulus of 1059 MPa and tensile stress of 37 MPa, comparable to thermosets.
• Demonstrated up to 80% recovery in modulus and tensile strength upon water contact due to dynamic boroxine bonds.
• Showcased superior adhesion to metal substrates and a significant modulus change (factor of 150) in response to water stimulus.

Conclusions:

• The developed dual cross-linked polymer system successfully integrates stiffness and self-healing properties.
• The water-responsive nature and tunable mechanical properties enable potential applications in micro/nanofabrication and advanced sensors.
• The material holds promise for wearable electronics and human healthcare applications.