Amine-Cured Glycidyl Esters as Dual Dynamic Epoxy Vitrimers

It is of greater significance to develop amine-cured epoxy vitrimers than conventional epoxy-carboxylic acid vitrimers because amines are the most widely curing agents than carboxylic acids. Considering that the reaction of amines with glycidyl esters can skillfully create dynamic hydroxyl esters, so we synthesized aliphatic and aromatic glycidyl esters and then cured them by amine-curing agents containing disulfide bonds. Here, besides the generated hydroxyl esters, the dynamic disulfide bonds are also integrated into the cross-linked network to form dual dynamic vitrimers. The synthesized glycidyl esters show very high-efficiency curing reactivity due to the lower activation energy. The properties of dual dynamic vitrimers can be easily tuned via the proportion of aromatic and aliphatic glycidyl esters to realize the transition from the rubber state to glass state. Moreover, the combinations of enhancement and toughening are achieved via the addition of aromatic glycidyl esters into dual dynamic vitrimers without sacrificing the curing activity and reprocessing property. Compared with single dynamic vitrimers, the dual dynamic vitrimers exhibit excellent reprocessing performances and unique rheological characteristics due to the exchange reactions of transesterification and disulfide exchange at high temperatures, which enables them to be reprocessed at 180 degrees C for only 5 min.