Glassy Dynamics of Epoxy-Amine Thermosets Containing Dynamic, Aromatic Disulfides

Continued progress in understanding the relaxations and mechanical performance of covalent adaptable networks (CANs) will lead to the further adoption of these unique materials across a wide range of applications. Using a model CAN system consisting of dynamic, aromatic disulfides in epoxy-amine thermosets, several network characteristics were found to vary as a function of disulfide concentration and topological placement. The mass density was found to increase significantly with the disulfide concentration, while the glass transition temperature decreased linearly with disulfide content (from 190 to 130 °C), as measured by modulated differential scanning calorimetry and dynamic mechanical analysis. Furthermore, the apparent activation energy of the glass transition, E g, as estimated by time–temperature superposition, decreased with increasing disulfide concentration. Significant changes in the sub-T g relaxations were also observed and correlate strongly with the concentration and placement of disulfide bonds within the network.