Sulfur-Rich Vitrimers From Oligosulfides and Epoxy Cross-Linkers With Tunable Mechanical Properties and Adhesive Performance

Abstract

Sulfur-rich vitrimers have attracted increasing interest due to their dynamic covalent networks and potential in sustainable materials. In this work, sulfur-based vitrimer networks were constructed via a two-step strategy by combining hydroxyl-functionalized oligosulfides with epoxy cross-linkers. The oligosulfides, containing dynamic oligosulfide (–Sx–) linkages, were synthesized through the oligomerization of elemental sulfur with cyclic disulfides, followed by cross-linking with bisphenol A diglycidyl ether or diethylene glycol diglycidyl ether in the presence of imidazole. By tuning the type and loading of epoxy cross-linkers, the resulting networks exhibit a wide range of mechanical properties, from rigid thermosets to soft and extensible materials, with tensile strengths up to 12.85 ± 2.73 MPa and elongations at break up to 44.40% ± 5.01%. In addition, these vitrimers demonstrate effective adhesive performance, achieving lap-shear strengths of up to 6.05 ± 0.99 MPa on steel substrates. This work provides a straightforward and versatile strategy for designing sulfur-rich vitrimer materials with tunable mechanical behavior and promising potential in structural adhesive applications.