Poly(epoxy-imine) vitrimers. Effect of the structure on the stress relaxation and creep resistance.

A series of polyimine-epoxy vitrimers has been synthesized using commercially available monomers using a two-step synthetic route to maximize the content of imine groups in the resulting structures. The first step consists of the synthesis of amine terminated polyimine oligomers, which were synthesized by a condensation reaction of terephthalaldehyde (TA) with different proportions of diethylenetriamine (DETA) and a polyetheramine (Jeffamine D-230 or D-400). After that, the obtained viscous oligomers were cross-linked with bisphenol A diglycidyl ether (DGEBA). The design of network architectures using this approach is a powerful tool that allows controlling the concentration of imine groups, the dimensions of the intermediate polyimine oligomer and the polarity and mobility of its chains, confirming that it is an effective way to tune the thermal, mechanical and thermomechanical properties of the final materials. Furthermore, this work confirmed that an accurate design of the network architecture allows simultaneously improving the two main requirements of vitrimers by increasing the content of imine groups: fast stress relaxation processes and high creep resistance. Stress relaxation curves proved that these polyimine vitrimers could relax the 63 % of the initial stress in less than 9.6 min at 160 °C without any added catalyst. Besides, replacing Jeffamine D-400 with Jeffamine D-230 in the imine oligomer increases the material's resistance to creep at service temperatures. All the materials prepared present high thermal stability and showed T g s between 31 and 93 °C. • A series of polyimine-epoxy vitrimers were synthesized by a two-step procedure. • Well-defined oligomers with known imine groups were synthetized. • Vitrimeric behavior and creep resistance were correlated with imine concentration. • Materials prepared with Jeffamine D-230 showed good creep resistance at 20 °C. • Chemical degradation of these vitrimers depends on the materials' composition. [ABSTRACT FROM AUTHOR]