A Chemically Recyclable 1,3,5‐Triazine‐Based Epoxy Thermoset Enabled by Nucleophilic Aromatic Substitution Reaction

ABSTRACT Developing recyclable thermosets without sacrificing structural integrity remains a significant hurdle in polymer circularity. In this study, we present a high‐performance, chemically recyclable epoxy thermoset based on 1,3,5‐triazine, demonstrating significant advancements in material recyclability and application potential. Utilizing liquid precursors, that is a trifunctional epoxy monomer (TOMTA) and a strategically selected secondary aromatic diamine hardener (MBMA), a cross‐linked network with a well‐defined architecture was produced under bulk conditions. The resulting thermoset exhibited exceptional thermal and mechanical properties as evidenced by a high glass transition temperature ( T g = 105°C), thermal stability ( T d5% = 256°C), a Young's modulus of 3.0 GPa, and a tensile strength of 96 MPa, placing the material in the same performance range of conventional epoxy resins. Driven by an optimized binary K 2 CO 3 /TBD catalytic system in ethanol, the network underwent depolymerization enabled by a nucleophilic aromatic substitution reaction (S N Ar), yielding the well‐defined building blocks TETA and the tetraol BDHPPM in 70% and 65%, respectively, via straightforward liquid‐liquid extraction. Re‐crosslinking these recovered building blocks regenerated the network, preserving nearly identical properties across multiple recycling cycles. The system was further applied as a debondable coating for glass. This 1,3,5‐triazine‐based network utilizing S N Ar chemistry provides a robust route to high‐performance, recyclable epoxy thermosets.