All-Around Universal and Photoelastic Self-Healing Elastomer with High Toughness and Resilience

Adv Sci (Weinh). 2021 Dec;8(24):e2103235. doi: 10.1002/advs.202103235. Epub 2021 Oct 18.

Abstract

Ultimately soft electronics seek affordable and high mechanical performance universal self-healing materials that can autonomously heal in harsh environments within short times scales. As of now, such features are not found in a single material. Herein, interpenetrated elastomer network with bimodal chain length distribution showing rapid autonomous healing in universal conditions (<7200 s) with high efficiency (up to 97.6 ± 4.8%) is reported. The bimodal elastomer displays strain-induced photoelastic effect and reinforcement which is responsible for its remarkable mechanical robustness (≈5.5 MPa stress at break and toughness ≈30 MJ m-3 ). The entropy-driven elasticity allows an unprecedented shape recovery efficiency (100%) even after fracturing and 100% resiliency up to its stretching limit (≈2000% strain). The elastomers can be mechanically conditioned leading to a state where they recover their shape extremely quickly after removal of stress (nearly order of magnitude faster than pristine elastomers). As a proof of concept, universal self-healing mechanochromic strain sensor is developed capable of operating in various environmental conditions and of changing its photonic band gap under mechanical stress.

Keywords: autonomous healing; hydroxypropyl cellulose; liquid crystal; mechanochromic; strain sensors; supramolecular; underwater self-healing.