Intrinsically self-healing crosslinked elastomer with mechanically robust based on dynamic urea bond and hydrogen bond for smart humidity sensor

Abstract

Employment of noncovalent bonds as reversible crosslinks have been applied in weldable and self-healing crosslinked polymer networks but result in limited mechanical properties. Herein, a robust, tunable, and fast healable poly(urethane-urea)-GMA (PG) elastomer with a combination of multiple hydrogen bonds and dynamic covalent urea bonds was designed via a photo-induced copolymerization. The resultant PG60 exhibited a tensile strength of 12.3 MPa, an elongation at break of 229%, a toughness of 16.08 MJ m−3, and a self-healing efficiency of 100.0%. By adjusting the content of dynamic crosslinkers, the mechanical strength and self-healability of the resulting elastomers can be optimized. The exceptional properties of the networks, including self-healing capability and remarkable robust mechanical behavior, are attributed to the presence of reversibly noncovalent hydrogen bonds and dynamically covalent urea bonds, which have been confirmed through stress relaxation tests. More importantly, this study not only presents a facile fabrication method for designing mechanically robust and fast self-healing crosslinked elastomers, but also shows great potential in smart humidity sensor.