Design of Self-Healing Supramolecular Rubbers with a Tunable Number of Chemical Cross-Links

Abstract

Supramolecular rubbers incorporating a large number of physical cross-links through cooperative hydrogen bonds display high self-healing properties but limited solvent and creep resistance due to the lack of chemical cross-links. Increasing both chemical cross-links and H-bonding is therefore desirable but limited by the functionality of monomers. The present work thus devises a convergent chemical platform permitting to increase the number of chemical cross-links without changing the concentration of hydrogen-bonding groups. Starting from a single reactive prepolymer, functionalized with a defined number of hydrogen-bonding groups, a series of networks presenting different ratios of diepoxide and tetraepoxide were prepared. The curing process (controlled by 2-MI catalyst), thermomechanical behavior, and tensile properties recovery of the cured materials were investigated. Gelation state was quantified and compared to theoretical predictions. The introduction of tetrafunctional epoxide in the presence of 2-MI gave rise to gelled materials characterized by higher rigidity and strength and significantly improved creep resistance. Self-healing was observed for all materials, with 50% to 100% complete recovery in a day depending on tetraepoxide content.

Design of Self-Healing Supramolecular Rubbers by Introducing Ionic Cross-Links into Natural Rubber via a Controlled Vulcanization

“…27 A developed covalently cross-linked network restricts the mobility of rubber chains, which adds difficulties to repair a mechanical damage. To avoid this unfavorable influence, the formation of covalent cross-link was retarded in the supramolecular network.…”

Fatigue of Self-Healing Nanofiber-based Composites: Static Test and Subcritical Crack Propagation

“…The broken bonds in these materials can be selfassembled and joined again. [24][25][26][27][28] In such cases, it is technically possible to have an unlimited number of healing cycles without an inherent lack of liquid healing agent.…”

A facile and controllable synthesis of dual‐crosslinked elastomers based on linear bifunctional polydimethylsiloxane oligomers

“…Besides, the formation of a hybrid network composed of hydrogen bond and covalent bond can also provide self‐healability and acceptable mechanical properties. A hydrogen bonded supramolecular elastomer with hybrid network was prepared from fatty acids (functionality > 2), dimethyltriamine (DETA) and urea . The resulting material is a mixture of hydrogen bonded oligomers, exhibits good mechanical properties and self‐healability at ambient temperature.…”