Polymers made by inverse vulcanization can be assembled, repaired, and recycled at room temperature through nucleophile-catalyzed S–S metathesis.

Inverse vulcanization provides dynamic and responsive materials made from elemental sulfur and unsaturated cross-linkers. These polymers have been used in av ariety of applicationss uch as energy storage, infrared optics, repairable materials, environmental remediation, and precision fertilizers. In spite of thesea dvances, there is an eed for methods to recycle and reprocess these polymers. In this study,p olymers prepared by inverse vulcanization are shown to undergo reactive compression molding. In this process, the reactive interfaces of sulfur polymers are brought into contact by mechanicalc ompression.U pon heating these molds at relatively low temperatures (% 100 8C), chemical bonding occurs at the polymer interfaces by SÀSm etathesis. This method of processing is distinct from previouss tudies on inverse vulcanization because the polymers examined in this study do not form al iquid phase when heated. Neither compression nor heatinga lone was sufficient to mold these polymers into new architectures, so this is an ew concept in the manipulation of sulfur polymers. Additionally,h igh-level ab initio calculations revealed that the weakest SÀSb ond in organic polysulfides decreases linearly in strength from as ulfur rank of 2t o4 ,b ut then remains constant at about 100kJmol À1 for highers ulfur rank. This is criticali nformation in engineering these polymers for SÀSm etathesis. Guidedb yt his insight, polymer repair,r ecycling, and repurposingi nto new composites was demonstrated.

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.

The reaction between sulfur and dicyclopentadiene was optimised to form a shelf stable and soluble low molecular weight oligomer. After a simple curing process at 140 °C the material was...

A polysulfide terpolymer made from canola oil, dicyclopentadiene, and elemental sulfur is synthesized and evaluated as bulk structural material. The unique polysulfide structure in this material allows the two polymer blocks to be bonded together through amine-catalyzed S-S metathesis. No exogenous adhesive is required: the polysulfide is both the bulk material and the mortar. The strength of the joined polymers is evaluated by a series of shear tests and compared to the bond strength obtained with commercially available superglue. The adhesion obtained via the S-S metathesis is stronger in all tests. To improve the mechanical properties of the terpolymer, carbon nanorods and carbon fibers are embedded in the polymer, with the latter leading to nearly a 16-fold increase in flexural strength. Prospects in sustainable construction are discussed.