Abstract
<jats:p>Covalent adaptive networks promise self-healing and reprocessability for soft materials, yet dynamic bond exchange typically compromises mechanical robustness and introduces energy dissipation under cyclic loading. Here we show that a one-pot Mannich polycondensation of guanidine, diamines, and formaldehyde generates tetrahydrotriazine (THT)-crosslinked gels (GuDAF) that simultaneously achieve compressive strength >2 MPa, optical transparency >90%, and hysteresis <5% over 100 cycles—a combination previously unattained in single covalent networks. By systematically varying diamine chain length and solvent systems, we establish a quantitative structure–property relationship revealing that solvent-mediated hydrogen bonding synergistically reinforces the covalent THT framework, overturning the view of solvents as passive plasticizers. Molecular dynamics simulations confirm that Gu4DAF possesses the densest hydrogen-bonding sites, explaining its solvent-dependent mechanical superiority. The dynamic junctions also confer autonomous self-healing, thermal reprocessability, and intrinsic piezoresistive sensitivity (gauge factor 2.33) without exogenous additives, positioning GuDAF gel as a platform bridging dynamic covalent chemistry and demanding load-bearing applications.</jats:p>