Synthesize and introduce bio-based aromatic s-triazine in epoxy resin: Enabling extremely high thermal stability, mechanical properties, and flame retardancy to achieve high-performance sustainable polymers

Developing bio-based epoxy resins with high thermal stability and mechanical properties as well as satisfactory intrinsic flame retardancy is of increasing demand, though this has always been limited by the lack of bio-based polyaromatic building blocks. Herein, a simple and universal method was proposed to synthesize an aromatic s-triazine derivative from biomass feedstock, vanillin, and the obtained compound can be employed to construct a bio-based epoxy precursor (THMT-EP). With 4,4′-diaminodiphenyl sulfone (DDS) as curing agent, thanks to the unique structures of aromatic s-triazine, the resulting cured THMT-EP/DDS presented remarkable integrated properties outperforming than commercial petroleum-based bisphenol A epoxy resin (DGEBA), including a record glass transition temperature of 300 °C, as well as a high flexural modulus of 4137 MPa and a flexural strength of 134.2 MPa, which were 120 °C, 53.9% and 14.3% higher than those of DGEBA/DDS, respectively. Furthermore, the cured THMT-EP/DDS also showed excellent intrinsic flame retardancy, passing the V-0 rating in UL-94 test. This study opens an avenue for the synthesis of bio-based feedstocks with rigid aromatic and functional structure, and contributes to the development of bio-based high-performance polymers.