Bioinspired Integrated Auxetic Elastomers Constructed by a Dual Dynamic Interfacial Healing Strategy

Area of Science:

• Materials Science
• Polymer Chemistry
• Mechanical Engineering

Background:

• Auxetic materials exhibit unique transverse expansion under axial stretching.
• Conventional auxetic materials often suffer from reduced mechanical performance due to subtractive manufacturing processes like cutting.
• Natural skeletal structures inspire a new approach to material design.

Purpose of the Study:

• To develop a void-free, integrated auxetic elastomer (IAE) with enhanced mechanical properties.
• To address the mechanical degradation issue in traditional auxetic materials.
• To create robust auxetic materials for engineering applications.

Main Methods:

• Fabrication of an IAE using a high-modulus cross-linked poly(urethane-urea) skeleton and a low-modulus non-cross-linked poly(urethane-urea) matrix.
• Utilizing disulfide bonds and hydrogen bonds for dual dynamic interfacial healing.
• Confirmation of properties through finite element analysis.

Main Results:

• The IAE is flat, void-free, and lacks sharp interfaces.
• Achieved 400% increase in fracture strength and 150% increase in elongation at break compared to the skeleton alone.
• Preserved negative Poisson's ratio (NPR) over a large strain range (0%-104%).

Conclusions:

• The integrated hybrid material approach successfully enhances mechanical performance while retaining auxetic properties.
• This method offers a promising solution for robust auxetic materials, overcoming limitations of subtractive manufacturing.
• The developed IAE demonstrates significant potential for advanced engineering applications requiring high performance and large deformation capabilities.