Fully bio-based epoxy resins from bisphenols of coumaroyl amide structure from lignin derived vanillin and tyramine

The conversion of renewable biomass into high-performance bio-based epoxy resins represents a key step toward sustainable polymer chemistry. In this work, a novel series of coumaroyl amide bisphenols, derived from lignin derived monophenols (vanillin, isovanillin, and 4-hydroxy-o-anisaldehyde) and tyramine, were synthesized through a Knoevenagel-Doebner condensation using a Meldrum's acid strategy. These unsymmetric bio-bisphenols were subsequently transformed into bis-epoxides (TMVE, TMIE, and TM42E) and cured with the bio-based diamine Priamine 1074 to form epoxy thermosets. Among them, the TMIE/1074 system exhibited the highest reactivity and thermal stability, with a char residue (R₇₅₀) of 20.1 % under nitrogen. Compared to petroleum-based DGEBA/1074, TMIE/1074 showed twice the impact strength (64.0 kJ/m²) while maintaining a comparable tensile strength (50.0 MPa). Moreover, the cured TMIE/1074 thermoset demonstrated excellent shape-memory behavior, highlighting its potential for advanced functional applications. This study provides an innovative route to designing high-performance, bio-based epoxy resins as sustainable alternatives to bisphenol A-based materials.