The discovery of inverse vulcanization has allowed stable polymers to be made from elemental sulfur, an unwanted by-product of the petrochemicals industry. However, further development of both the chemistry and applications is handicapped by the restricted choice of cross-linkers and the elevated temperatures required for polymerisation. Here we report the catalysis of inverse vulcanization reactions. This catalytic method is effective for a wide range of crosslinkers reduces the required reaction temperature and reaction time, prevents harmful H₂S production, increases yield, improves properties, and allows crosslinkers that would be otherwise unreactive to be used. Thus, inverse vulcanization becomes more widely applicable, efficient, eco-friendly and productive than the previous routes, not only broadening the fundamental chemistry itself, but also opening the door for the industrialization and broad application of these fascinating materials.

The invention of inverse vulcanization provides great opportunities for generating functional polymers directly from elemental sulfur, an industrial by‐product. However, unsatisfactory mechanical properties have limited the scope for wider applications of these exciting materials. Here, we report an effective synthesis method that significantly improves mechanical properties of sulfur‐polymers and allows control of performance. A linear pre‐polymer containing hydroxyl functional group was produced, which could be stored at room temperature for long periods of time. This pre‐polymer was then further crosslinked by difunctional isocyanate secondary crosslinker. By adjusting the molar ratio of crosslinking functional groups, the tensile strength was controlled, ranging from 0.14±0.01 MPa to 20.17±2.18 MPa, and strain was varied from 11.85±0.88 % to 51.20±5.75 %. Control of hardness, flexibility, solubility and function of the material were also demonstrated. We were able to produce materials with suitable combination of flexibility and strength, with excellent shape memory function. Combined with the unique dynamic property of S−S bonds, these polymer networks have an attractive, vitrimer‐like ability for being reshaped and recycled, despite their crosslinked structures. This new synthesis method could open the door for wider applications of sustainable sulfur‐polymers.

Elemental sulfur is an abundant by-product of the petrochemical industry, but polymers formed from pure sulfur cannot be used because they are not stable and depolymerize to the monomer, S₈. Inverse vulcanization reported recently uses vinylic monomers as crosslinkers to stabilize polymers made from elemental sulfur. Here we report that the catalyst sodium diethyldithiocarbamate trihydrate allows inverse vulcanization to be conducted at low temperatures (110 °C), even below the melting point of sulfur (120 °C). Lower reaction temperatures are beneficial for not only energy economy, but also in preventing dangerous auto-acceleration and hydrogen sulfide generation, and allowing low boiling point monomers to be used. Excess catalyst can be recovered from the polymers, and despite a crosslinked structure, the reversibility of the S–S bonds allows the polymers to be recycled.

A copolymer made from sulfur and dicyclopentadiene was useful as a mercury sorbent, and also as a protective and repairable coating.