Neighboring-group-participating ionic crosslinks defy trade-offs in ultra-strong, reprocessable, and antibacterial thermosetting polyurethanes

The development of thermosetting polyurethane elastomers (TPUEs) face an inherent contradiction between mechanical robustness and re-processability in covalent adaptable networks (CANs), where conventional dynamic bonds either compromise strength (<20 MPa) or require prohibitively high activation temperatures (>150 °C). Herein, we address this long-standing challenge through an innovative dynamic crosslinking strategy based on neighboring-group participation (NGP) of thiabicyclo [3.3.1] nonane (S-BCN), constructing ionic CAN (SPU_2MC). The double chair-conformation and cation-π interactions in SPU_2MC synergistically enhance mechanical strength (31.1 MPa tensile strength, a 215% increase compared to the glycerol-crosslinked control group (GPU) at the same crosslinking density). Simultaneously, rapid dynamic bond exchange enabled by the NGP allows reprocessing at 110 °C (thermal recycling) and 60 °C (solvent recycling). Benefiting from the high charge density, SPU_2MC also exhibits intrinsic antimicrobial activity (>99.9% inhibition against E. coli and S. aureus) by adhering to bacterial cell walls and disrupting membrane integrity. For the first time, a catalyst-free dynamic crosslinking strategy achieves synergistic optimization of mechanical performance, re-processability, and antibacterial functionality within a single TPUE system. Such materials show great promise for emerging applications in flexible electronics and protective components.