Recyclable Biobased Dynamic Cross-Linking Epoxy Thermosets Containing Vinylogous Urethane Bonds with Shape Memory Properties

A series of recyclable biobased dynamic cross-linking epoxy polymers containing vinylogous urethane bonds (ISVUEs) were constructed under solvent-free conditions by using diglycidyl ether of isosorbide and isosorbide-bis-acetoacetate derived from biobased isosorbide and cured with trifunctional and difunctional primary amines. The influence of amine curing agents and dynamic bond contents on the cross-linking density, thermal stability, and tensile and recycle properties of ISVUEs was investigated. The results showed that triamine as the cross-linker endowed a significant effect on the properties of ISVUEs. The tensile strength of the polymer with tris (2-aminoethyl) amine as the triamine reached 40.3 MPa, with only a small increase in tensile strength in three recycling cycles. The polymer with polyetheramine T403 as the triamine showed an elongation at break of 171.9% and a shape recovery of up to 84.5%, which exhibited a good shape memory effect. Meanwhile, the ISVUEs exhibit good recyclable properties when the amount of dynamic bond content is 66.7%. The design provides a strategy for introducing vinylogous urethane bonds into biobased epoxy polymers with potential smart applications such as textiles, medical implants, and soft robotics.