A Fast Room-Temperature Self-Healing Glassy Polyurethane

We designed and synthesized a colorless transparent glassy polyurethane assembled using low-molecular-weight oligomers carrying a large number of loosely packed weak hydrogen bonds (H-bonds), which has a glass transition temperature (T-g) up to 36.8 degrees C and behaves unprecedentedly robust stiffness with a tensile Young's modulus of 1.56 +/- 0.03 GPa. Fast room-temperature self-healing was observed in this polymer network: the broken glassy polyurethane (GPU) specimen can recover to a tensile strength up 7.74 +/- 0.76 MPa after healing for as little as 10 min, which is prominent compared to reported room-temperature self-healing polymers. The high density of loose-packed hydrogen bonds can reversibly dissociate/associate below T-g of GPU (that is secondary relaxation), which enables the reconfiguration of the damaged network in the fractured interfaces, despite the extremely slow diffusion dynamics of molecular chains under room temperature. This GPU shows potential application as an optical lens.

Automated summary

The newly designed glassy polyurethane has a high glass transition temperature, robust stiffness, and remarkable self-healing ability due to the high density of loosely packed hydrogen bonds with reversible dissociation and association capabilities below room temperature.