Tough and Recyclable Ethylene–Vinyl Acetate Elastomers Based on the Stress-Induced Phase Separation Strategy

Ethylene–vinyl acetate rubber (EVM) is a high-performance elastomer widely used across various sectors including electronics, communications, energy, and transportation. However, its relatively low mechanical strength restricts broader applications. Introducing epoxy groups and employing cross-linking methods have proven effective in enhancing mechanical performance, but the formation of permanent cross-linked networks compromises the material’s recyclability and reprocessability, which conflicts with sustainable development principles. In this study, we synthesized ethylene–vinyl acetate–glycidyl methacrylate (EVGMAx) terpolymers with varying epoxy group content by incorporating a third monomer, followed by comprehensive structural characterization. Instead of conventional cross-linking, a recyclable ethylene–vinyl acetate elastomer with outstanding mechanical properties was developed by using a stress-induced phase separation (SIPS) strategy. Mechanical tests revealed that the samples achieved a tensile strength of 16.9 MPa, significantly surpassing that of recently reported ethylene–vinyl acetate-based polymers while maintaining an elongation at break of 305.8%. Additionally, the rapid dissolution in acetone and the stability of properties after multiple thermal reprocessing demonstrate the polymer’s excellent recyclability and reprocessability. The phase separation behavior was further examined using atomic force microscopy (AFM), scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA), elucidating the underlying SIPS mechanism. Finally, a conductive ethylene–vinyl acetate elastomer was fabricated by incorporating multiwalled carbon nanotubes (MWCNTs), demonstrating the material’s potential as a strain sensor in flexible electronic applications.