Design of Robust and Recyclable Covalent Elastomeric Networks through Dynamic Enamine–Urea Bonds

The design of ultrastrong and recyclable covalent elastomeric networks with new dynamic exchange chemistry remains a challenge. Herein, the new dynamic exchange chemistry of enamine-urea bonds (EUBs) was developed and introduced into covalent elastomeric networks of poly(enamine-urea)s (PEUs) integrating both unconjugated polyurethane chains and conjugated polypyrrole (PPy) chains, enabling ultrastrong mechanical strength and recyclability. The dynamic exchange chemistry of EUBs was verified by small molecule model experiments and stress relaxation of PEUs with EUBs was introduced. The PEUs exhibited superior tensile strength (41.41 ± 0.46 MPa), high stretchability (1482.03 ± 86.48%), and excellent catalyst-free recyclability and reprocessability. In addition, introducing free PPy led to an enhanced tensile strength of 164.6% and enhanced photothermal effect by 3.25 times, enabling excellent photothermal scratch and fracture healing. Finally, the photothermal desalinator and photothermal power generator were designed and integrated based on the enhanced photothermal PEUs for different application scenarios, demonstrating the excellent ability of photothermal desalination as well as an efficient transformation from light energy to electrical energy and then to mechanical energy.