Engineered self-healable elastomer with giant strength and toughness via phase regulation and mechano-responsive self-reinforcing

Acquiring simultaneous high strength and toughness, and efficient self-healability of polyurethane (PU) elastomer is of great challenge due to their exclusive dependence on hard segments. Herein, a transparent, puncture-resistant, notch-insensitive, resilient and self-healable elastomer (PDO-IP2.5) with giant tensile strength (29.5 ± 0.9 MPa), excellent toughness (124.9 ± 2.2 MJ/m3), outstanding fracture energy (83.9 kJ/m2), high puncture energy (625 mJ) and balanced self-healing efficiencies (SEs calculated in tensile strength, elongation at break and toughness > 95%) and fast physical wound re-mending (~60 s upon hot airflow) is successfully developed through deliberate phase regulation, i.e. rational design of asymmetric and bulky hard segments and optimization of hard segments content. The resulting loosely-packed hard domains play a pivotal role in conferring self-healability and generating stress-induced crystallization (SIC) of polytetramethylene ether glycol (PTMEG) chains during large deformation, which not only facilitates the chain mobility for heat-responsive dynamic exchange of hydrogen bonds and oxime-carbamate but also dissipate external force during stretching to help the SIC evolution of PTMEG chains. The SIC domains act as physical crosslinking junctions and reinforcing phase, resulting in remarkable strengthening and toughening. This strategy could enlighten researchers in academia and industry to develop strong and tough elastic materials. In the meantime, the unique comprehensive performance of the as-synthesized elastomer confers it with potential practical use in engineer-grade fields of puncture-resistant tire sealant and durable protective coatings.