High-Performance Cross-Linked Self-Healing Material Based on Multiple Dynamic Bonds

Abstract

There is a trade-off between mechanical and self-healing performance for crosslinked self-healing materials. Herein, we design a polyurethane material containing triple synergy dynamic bonds to address the dilemma. The as-prepared polyurethane exhibits a maximum stress of 27.3 MPa and excellent self-healing performance. Specifically, boric acid is used as a cross-linker and the network cross-linked with boronic ester bonds under alkaline conditions is highly beneficial in terms of mechanical properties. Meanwhile, disulfide bonds and reversible boronic ester bonds located at the cross-linked point and main chain are successively broken upon being damaged, which is conducive to better fluidity of chains and endows the material with superior healing efficiency and multiple cycles of healing. Consequently, the high-performance self-healing material is of great potential in the fields of high-performance coating, aerospace, and load-bearing rubber.

Design Principles of Interfacial Dynamic Bonds in Self‐Healing Materials: What are the Parameters?

“…By tailoring the amount 'disulfide to polysulfide ratio', full recovery of mechanical performance and healing capability were achieved. Similarly, Xu et.al [196] 2020, designed a polyurethane elastomer with triple synergy dynamic bonds based on boric acid and SÀ S cross-links to overcome the tradeoff between mechanical and self-healing performance. Here, the boronic ester bonds under alkaline conditions were found to be highly beneficial in improving the mechanical properties (tensile stress and elongation at break of 27.3 MPa and 1177%), while the SÀ S bonds served as reversible cross-links and were responsible for a self-healing efficiency of 99% after treatment at 60°C for 24 h. Further, the synergistic combination of SÀ S bonds and reversible boronic ester bonds enhanced the segmental mobility resulting in lowering T g and transition activation energy.…”

Dually Crosslinked Polymer Networks Incorporating Dynamic Covalent Bonds

“…In a recent study, Xu et al [ 111 ] designed a PUR with three complementary dynamic bonds. In addition to the intrinsic hydrogen bonding ability of the urethane groups, the polymer backbone is equipped with thermo-responsive disulfide bonds, and the system was further chemically crosslinked with boronic esters.…”

Polythiourethanes Crosslinked with Dynamic Disulfide Bonds: Synthesis via Nonisocyanate Approach, Thermomechanical and Reprocessing Properties

“…Second, disulfide bond itself is one of important dynamic covalent bonds, metathesis reaction of which would endow the materials with self‐healing or reprocessing properties. [ 44–47 ] As a result, the application of the materials can be significantly broadened. In addition, the crosslinked PTUs can be applied as specific optical materials since the materials have quite high refractive indices due to their high contents of sulfur element.…”