A dieugenol-based epoxy monomer with high bio-based content, low viscosity and low flammability

A renewable eugenol-based biphenyl bifunctional epoxy monomer (DEUEP) is synthesized via a facile method. Eugenol is coupled into 5,5 '-dieugenol and then glycidized to yield DEUEP with a potentially 100% biobased content in a high purity (96%). DEUEP displays a lower viscosity (9.2 vs. 20.6 Pa.s at 25 degrees C) and a flow activation energy (60.4 +/- 0.4 vs. 81.1 +/- 0.4 kJ/mol) than a commodity bisphenol A-based epoxy prepolymer (E54) does. With a 3,3 '-diaminodiphenylsulfone (33DDS) hardener, DEUEP/33DDS is found to express the reactivity identical to E54/33DDS with a similar activation energy (similar to 62 kJ/mol). The cured DEUEP/33DDS thermoset is systematically examined and compared with E54/33DDS in terms of dynamic mechanical properties, thermal stability, flammability, flexural, impact and shear properties, fracture behaviors, water resistance, and wettability. DEUEP/33DDS has a lower flammability as indicated by the increased limited oxygen index (26.4% vs. 22.1%), the decreased heat release rate (HRR), total heat release (THR) and heat capacity (HR) by 46%, 33% and 46%, respectively. DEUEP/33DDS has T-g of 120.9 degrees C, a storage modulus of 2.57 GPa (25 degrees C), a higher char yield of 32.2% (750 degrees C in N-2), and a higher water-contact angle of 110.6 degrees.

Automated summary

DEUEP, a renewable eugenol-based biphenyl bifunctional epoxy monomer, exhibits lower viscosity and potentially 100% biobased content. Compared to E54, DEUEP/33DDS shows lower flammability and higher thermal stability.