Healable, Recyclable, and Ultra-Tough Waterborne Polyurethane Elastomer Achieved through High-Density Hydrogen Bonding Cross-Linking Strategy

With the increasing popularity of elastomers in industry
and daily
life, their high performance and functionality have attracted widespread
attention. However, it is a great challenge for them to possess both
high mechanical properties and excellent healing and recovery capabilities
due to the limitations of the preparation methods and the intrinsic
microstructure of the elastomers. In this study, a strategy of ice-controlled
interfacial stepwise cross-linking was proposed to prepare the waterborne
polyurethane-based elastomers with ultrahigh-density hydrogen bonding
interaction achieved by enhancing the utilization rate of phenol hydroxyl
groups of tannic acid to the maximum extent. The elastomers have incredible
mechanical properties, including ultrahigh toughness of 1.03 GJ m–3 (which represents the highest level among polyurethane
elastomers prepared through common processing techniques to date),
extremely high true fracture stress of ∼1.9 GPa, world-record
fracture energy of 520 kJ m–2, and exciting multiple
functional characteristics, such as highly efficient self-healing
ability of 10 min, high resistance to physical damage and chemical
corrosion, broad temperature and frequency damping effects, good shape
memory effect, and excellent melt-processing recyclability and solvent
recyclability. These robust multifunctional elastomers represent considerable
potential in various fields, from defense and military industry and
civil transportation to precision manufacturing, etc.