Hydrophobic Nanodomainsand Bulky Anion-Mediated SoftCross-Links Enable Strong, Tough, Water-Resistant, and RecyclablePlastics

High-performance, intrinsically sustainable plastics that simultaneously combine high strength, high modulus, toughness, and environmental stability remain elusive owing to the inherent trade-off between strength and toughness and the limited stability of noncovalent cross-links that enable recyclability. Here, we report a class of poly(urea–urethane) (PUU) plastics that reconcile these competing requirements through synergistic reinforcement by in situ-formed rigid hydrophobic nanodomains and bulky soft ionic cross-links. The incorporated bis(trifluoromethanesulfonyl)imide (TFSI–) anions increase interchain spacing and promote energy dissipation, while dynamically cross-linking cationic groups on PUU chains to compensate for the strength loss associated with increased free volume. The plastics exhibit a yield strength of 97.2 MPa, a Young’s modulus of 2.02 GPa, and a toughness of 14.6 MJ m–3, while maintaining exceptional resistance to water, acidic, and alkaline aqueous solutions. The plastics are readily reprocessable and can serve as matrices for high-performance carbon-fiber composites, enabling facile and nondestructive carbon-fiber recovery.