The enhanced repairable properties of epoxy-imide resins via the introduction of multiple hydrogen bonding interactions of UPy

In this paper, 2-ureido-4[1H]-pyrimidinone (UPy) containing quadruple hydrogen bonding interaction was selected to introduce into the polyimide containing epoxy-imide, the dynamic covalent network and hydrogen bonds networks would be constructed via the interaction of carbamide groups, isocyanate groups, acylamino groups, hydroxyl groups and amino groups, which are conducive to the self-repairing properties and mechanical properties. The aim of this paper is to prepare a repairable, recyclable and repair-condition-friendly epoxy-imide material. FT-IR, XPS and tensile tests were used to characterize the structure and mechanical properties. The repair conditions were investigated. Due to the introduction of UPy, at the same temperature of 60 ℃, the completely repaired time for EP-UPy3 scratches was 30 min, while for EP-3 scratches, the completely repaired time was 120 min. The repair conditions were further improved due to the action of UPy. More critically, UPy contents have an important effect on the mechanical properties. The tensile strength of EP-UPy3 (0.01 mol) samples achieved the maximum (27.89 MPa), which is much higher than that of EP samples (9.69 MPa) and the tensile strength of the repaired EP-UPy3 (27.75 MPa) is still higher than that of the repaired EP-3 (9.02 MPa), confirming that the introduction of UPy is significant to the improved mechanical properties of epoxy-imide materials. Moreover, the samples of EP-UPy have recyclable and processable properties, which is significant to broaden the epoxy-imine self-repair materials with a valued application prospect.