Bio‐Based Polybenzoxazine Vitrimer With High Thermal Stability, Reprocessability, and Chemical Resistance

ABSTRACT This work reports a bio‐based polybenzoxazine vitrimer that simultaneously achieves high glass transition temperature ( T g ), excellent reprocessability, and outstanding chemical resistance. The synthesis involves first esterifying phloretic acid with tyrosol to form bisphenol ester (BPE), which then undergoes Mannich condensation to yield the benzoxazine monomer, finally polymerized via ring‐opening to afford ester‐containing polybenzoxazine vitrimer (PEBZ). Because of the dynamic transesterification reactions (TERs), PEBZ has processable performance. The tensile strength retention rates of PEBZ after three times reprocessing were 90.4%, 72.1%, and 57.0%. PEBZ also has excellent thermal performance. The T g is as high as 217°C, and its thermal decomposition temperatures T d5 and T d10 are 338°C and 369°C, respectively, with a carbon yield of 40.3%. These thermal characteristics remain basically unchanged after three post‐treatment cycles. Due to the high crosslinking density and rigid framework of benzoxazine, PEBZ has excellent chemical resistance. This polybenzoxazine vitrimer achieves a unity of high performance and recyclability, providing a broader range of application scenarios for processable materials.