Tailored Prestretching Induced Supramolecular Reconfiguration for Constructing Ultrastrong Polyurethane-Urea...

Polyurethane elastomers (PUEs) can achieve high mechanical properties via microstructural design. However, traditional synthetic as well as post-treatment methods have difficulty in breaking through the limitation on the structural optimization and mechanical strength for PUEs. Herein, this study achieves a significant mechanical enhancement of polyurethane elastomers (PUEs) based on prestretching induced structural ordering. A polyurethane-urea elastomer with a unique linear backbone structure and soft/hard phase separation features, which is rich in abundant hydrogen-bonding sites, is synthesized. The specific prestretching treatment promotes chain orientation and rearrangement, thereby facilitating the formation of more ordered supramolecular hydrogen bonds and inducing strain induced crystallization, which significantly improve the strength of the material. The prestretched polyurethane-urea elastomer achieves an ultrahigh tensile strength of 140.14 MPa and a toughness of 355.76 MJ m^-3. Besides, stability against solvents is also achieved. Characterizations including infrared spectra and X-ray scattering, among others, reveal the strengthening mechanisms in different dimensions, which are in accordance with simulations. This work provides a facile and effective design strategy for fabricating ultrahigh-strength and tough polyurethane elastomers.