An investigation on the performance of epoxy vitrimers based on disulfide bond

The research for self-healing epoxy vitrimers has attracted a lot of attention over the years. However, due to the special structure of the epoxy molecular chain, which limits its movement ability, epoxy vitrimers usually need to be healed under high temperature and pressure. So it is relatively difficult to healing. Here, a new type of cross-linked network is obtained by cross-linking hydrogenated bisphenol A epoxy resin and polypropylene glycol diglycidyl ether (PPGDGE) as hard and soft segments with an amine curing agent containing disulfide bonds. The addition of PPGDGE can improve the mobility of the molecular chains in the cross-linked network we designed, thereby obtaining a novel epoxy vitrimers with better healing properties. The effect of PPGDGE content on the mechanical properties and self-healing properties of the material was studied. The ideal sample HEP-3 has a good tensile strength (33.4 MPa) and a completely broken sample can achieve a good self-healing rate (71.5%) at 100 degrees C for 3 h without high pressure. In addition, the ideal sample also has excellent shape memory properties (shape memory fixity ratio R-f = 97.1%, shape recovery ratio R-r = 94.9%). Moreover, due to the existence of the dynamic disulfide bond introduced by the curing agent 2-aminophenyl disulfide, compared with traditional thermosetting epoxy resins, epoxy vitrimers prepared by us can be reshaped or postprocessed like thermoplastic polymers under specific conditions. These characteristics will become the guarantee for expanding the application range of epoxy materials.