Disulfide vitrimeric materials based on cystamine and diepoxy eugenol as bio-based monomers

Abstract

This study reports the synthesis and characterization of bio-based disulfide vitrimers obtained from diepoxy eugenol and cystamine through an epoxy-amine polycondensation process. TREN was added to the formulation in varying proportions to increase the crosslinking density. Although TREN reduced the number of disulfide groups in the vitrimers, it resulted in a maximum relaxation rate at a proportion of 25%. The vitrimers were characterized using FTIR, TGA, and thermomechanical analysis, and their Tg values, determined by DSC, ranged from 75 to 103 °C with increasing TREN proportion. The vitrimers rapidly relax with a relaxation time (τ) of 8.5 min at 170 °C. The addition of TREN decreased the relaxation times from 2.8 to 1.03 min by catalyzing the disulfide metathesis and achieving a balance between the proportion of disulfide bonds and the content of nucleophilic tertiary amines. Creep tests were performed at a wide range of temperatures to investigate the viscosity of the material below and above the Tgs. The topology freezing temperatures were calculated from the creep tests, and Tv values below Tg in all cases confirmed the catalytic effect of tertiary amines on the disulfide exchange reaction.