Cross-Linkable and Self-Foaming Polysulfide Materials for Repairable and Mercury Capture Applications

Inverse vulcanization involves reactions between elemental sulfur and unsaturated organic compounds to result in polysulfide materials. In this work, a Meldrum’s acid-containing styrene compound (MA-St) has been employed in the inverse vulcanization process for introduction of MA moieties to the corresponding polysulfide material (poly(S-MA-St)). Poly(S-MA-St) possesses self-cross-linking ability based on the sequential MA thermolysis and ketene (generated with MA thermolysis) dimerization reactions. With employing CO2, evolved with MA thermolysis reaction, as a foaming agent, poly(S-MA-St) also exhibits self-foaming feature in the thermally cross-linking process. Moreover, cross-linked poly(S-MA-St) material shows repairable property based on the dynamic polysulfide chains. As a result, poly(S-MA-St) is an effective agent for imparting repairable property to other polymers. On the other hand, cross-linked and foamed poly(S-MA-St), which possesses polysulfide chains and rich oxygen atoms and porous structure, has demonstrated a mercury absorption capacity of 52.0 ± 1.8 mg Hg/g sample. While a 100 mg sample being applied to 10 mL HgCl2 aqueous solution of a concentration of 2240 ppb in 3 h, a high mercury removal efficiency of 96% has been recorded. This work has demonstrated a new class of functional polysulfide materials on the viewpoints of both synthetic chemistry and application targets.