Stretchable and Durable Inverse Vulcanized Polymers with Chemical and Thermal Recycling

Inverse vulcanized polymer materials have received considerable attention as a way to use sulfur, an industrial byproduct, as a starting material for synthesis. The resulting high-sulfur content polymers have also been investigated because their properties give rise to promising applications such as infrared imaging, energy storage, and heavy metal capture due to their unique structure. However, synthesis of a flexible sulfur polymer network which shows good mechanical properties combining high strength, high elongation, and high toughness is still a significant challenge. Moreover, further exploration of the properties of sulfur polymers to better understand the relationship between the polymers' structure with their performance is still needed. Here, a range of cross-linked sulfur polymers with high tensile elongation and toughness and without losing high strength were successfully synthesized. The obtained cross-linked sulfur polymers show high solvent tolerance in most organic solvents but are demonstrated to be chemically de-cross-linked in polar solvents dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone and can be re-cross-linked after removing the solvent due to the high sulfur ranks present in the polymer network. Despite the significantly improved mechanical properties, highly efficient thermal recycling performance typical of inverse vulcanized polymers was retained. Flexibility and durability, combined with chemical and thermal recycling, could open a new door for wider applications of inverse vulcanized polymers.