A mechanically strong, ultra-tough and room-temperature self-healing ionic conductive elastomer based on octopus-like physical cross-linker tannic acid and a robust polyurethane substrate

Abstract

Robust ionic conductive elastomers (ICEs) play an indispensable role in many applications. However, the excellent mechanical strength often conflicts with high ionic conductivity and self-healing ability in ICEs. In this work, adipic dihydrazide is initially incorporated into a polyurethane backbone to prepare an ultra-robust elastomer (PU-AD) based on the hydrogen bond arrays. PU-AD exhibits outstanding tensile strength (∼58.4 MPa) and excellent toughness (∼1205.8 MJ m⁻³). Then, based on this substrate, a series of ICEs (PU-IL-TA) are prepared by loading ionic liquids and a physical cross-linker, tannic acid (TA). On the one hand, the bulky octopus-like TA can readily “capture” multiple polymer chains within the ICE to form a physical cross-linked network through the numerous hydrogen bonding interactions. On the other hand, the bulky structure of TA can increase the distance between polymer chains, which mitigates the negative effect of crosslinking on ion transport. Consequently, PU-100IL-10TA exhibits high tensile strength (∼16.2 MPa), a record toughness (∼191.6 MJ m⁻³), and excellent fracture energy (∼80 kJ m⁻²), while also maintaining a good ionic conductivity (1.2 × 10⁻⁴ S cm⁻¹) and high room-temperature healing efficiency (∼95%). The elaborately designed ICEs offer a novel preparation strategy for achieving a balance of mechanical strength, self-healing properties, and ionic conductivity.