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Self-adhesive multi-fiber materials that bond under mechanical strain

Multi-fiber materials that adapt to mechanical loading through changes in fiber network structure and inter-fiber bonding, enabling self-adhesion and increased tensile strength.

Problem:

Multi-fiber materials are utilized in many applications ranging from textiles to tissue engineering. While current multi-fiber materials are able to adapt their shape to the structure of interest, they have limited mechanical strength, and therefore, fail easily under strain. Furthermore, these materials have weak self-adhesive properties, preventing them from holding their shape once in place.

Solution:

This invention describes a new approach for designing multi-fiber materials that provides several advantages over currently available materials. Individual fibers in the materials are designed to have specific chemistries that allow new chemical bonds to form under mechanical strain. As a result, these new bonds increase the tensile strength of the material and allow it to adhere to itself.

Technology Overview:

In this technology, multi-fiber materials are synthesized to have at least two fiber populations with compatible chemistries, such as aldehyde and hydrazide groups (See Figure). Upon mechanical strain, the chemical groups on each fiber population will come into contact and undergo a chemical reaction to form new bonds. Even after the mechanical strain is removed, these new bonds maintain the fiber alignment and help increase tensile strength. This also provides the multi-fiber material with exceptional self-adhesive properties, allowing it to hold its shape without the need for additional glues or bonding steps.

Advantages:

Provides 14-fold higher adhesive strength compared to traditional multi-fiber materials
The fiber backbone, chemical groups, and processing methods can all be fully customized for the application of interest
Self-adhesion is possible under a variety of strains including stretching, twisting, stacking and rolling
The tensile strength of the material improves under strain, and fiber alignment is maintained after the strain is removed

Schematic for the self-adhesive multi-fiber materials. In this multi-fiber system, fibers are synthesized to have complementary chemistries such as aldehyde (green) and hydrazide (red) groups. (A) When these fibers experience mechanical strain (such as stretching), these groups come into contact and form new chemical bonds with each other. Even when the mechanical strain is removed, these new bonds remain in place. (B) Complex interactions and self-adhesion can also be achieved by twisting, stacking, and rolling the multi-fiber system. (Figure source: Davidson et al. Advance Materials, 2019, 32, 1905719)