Catechol-modified epoxy backbones for multifunctional and ultra-tough thermoset

Widely used traditional thermosets have drawn great attention due to their advantageous features such as excellent stability, mechanical reliability etc. However, brittleness is still the weak point in their extensive applications. Herein, a synthetic strategy to incorporate catechol groups into polymer structures via thiol-epoxy click chemistry was developed, the covalent and iron-catechol coordination bonds are combined to build up the material consisting of two types of crosslinks. As an important design feature of thermoset, catechol moiety provided the potential of gaining recoverable hysteretic energy dissipation through iron-catechol complexes. Favorable thermal properties comparable to commercial resin were retained, and mechanical testing revealed the thermoset exhibited high extensibility, such that it can be stretched to over 100 % with a fracture strength of 31.16 MPa, along with the tensile strength can be maintained 90.53 % after 5 cycles at the strain of 50 %. The synergistic interaction additionally providing the possibility of shape memory response to specific environmental changes, either by heat or by ultraviolet light. These behaviors further highlight the utility of dynamic coordinate bonds in the preparation of versatile thermosets, which could be potentially applied in smart devices and advanced materials.