Self-healable gradient copolymers

Self-healing materials typically suffer from poor mechanical performance in terms of practical applications. Herein, a self-healable copolymer with a gradient distribution of hard segments on ionic polymer chains is designed. By the optimization of the monomer sequences and physical cross-linking, the copolymer exhibits excellent mechanical properties with Young's modulus up to 286 MPa and toughness over 33 MJ m(-3), which represents a significant improvement compared with traditional selfhealing materials. Imidazolium in this copolymer not only generates strong dynamic ionic associations and imparts mending ability, but also provides ionic conductivity for potential device applications. Environment-insensitive self-healing in the presence of moisture, water and artificial sweat is achieved. Strain sensors with rapid response (<114 ms) and high durability ( no performance decrease after 7000 cycles of tensile test) are fabricated using the gradient copolymers, opening an avenue for highperformance wearable devices using polymeric materials.