Rapidly Adaptive Aromatic–Aliphatic Polyester Networks Enabled by <scp>TBD</scp> ‐Catalyzed Bond Exchange

ABSTRACT Aromatic–aliphatic polyester covalent adaptable networks (CANs) were synthesized from dimethyl terephthalate (DMT), 1,4‐butanediol (BDO), and pentaerythritol (PER) by organocatalyst‐assisted transesterification. Network structure tuning via systematically varying the ratio of difunctional and multifunctional monomers was possible, allowing us to establish a direct relationship between cross‐link density and macroscopic properties. Rigid aromatic terephthalate moieties increase mechanical resistance and modulus, while flexible BDO moieties preserve the mechanical deformability of the polymer network. Increased cross‐linking, as confirmed by dynamic mechanical analysis, is reflected in the storage modulus and effective cross‐link density ( ν e = 2.5 × 10 3 mol/m 3 ). Analysis of stress relaxation demonstrates bond exchange at elevated temperature, characteristic of CANs, with an activation energy of about 86 kJ/mol. Significantly higher reactivity of TBD promotes bond‐exchange reactions in CANs, providing opportunities for thermal reprocessing and welding, as well as self‐healing (UTS: ≥ 95%), which are not observed in catalyst‐free controls with inferior mechanical properties and dynamic behavior. High thermal stability (~200°C) enables easy, safe processing and healing of the material below its degradation temperature.