Tuning the static and dynamic properties of epoxy vitrimers through modulation of cross-link density

Vitrimers, a polymer class that combines the benefits of thermosetting plastics and thermoplastics, have extensive potential applications in our daily lives and industry. Effectively controlling the dynamic properties of vitrimer materials has received considerable attention. This research prepared a series of dynamic epoxy crosslinking network with varying crosslinking densities by introducing reactive monofunctional small-molecule epoxy monomers through a transesterification reaction. Stress relaxation behavior confirmed the impact of small molecular epoxy on the rearrangement of the transesterification topological network. The findings indicated that decreasing the crosslinking density of the resin resulted in shorter stress relaxation time. Adding small molecular epoxy from 0% to 5% increased the tensile strength of the material from 13.2 MPa to 18.1 MPa. The findings demonstrate that it is efficient to adjust the dynamic properties of glass-like polymers by changing the cross-linking density. Furthermore, the mechanical properties of glass-like polymers can be enhanced by appropriately reducing the cross-linking density, which offers a new method for preparing vitrimer materials with desirable properties.