Electrochemical Synthesis of Poly(trisulfides)

With increasing interest in high sulfur content polymers,thereis a need to develop new methods for their synthesis that featureimproved safety and control of structure. In this report, electrochemicallyinitiated ring-opening polymerization of norbornene-based cyclic trisulfidemonomers delivered well-defined, linear poly-(trisulfides), which weresolution processable. Electrochemistry provided a controlled initiationstep that obviates the need for hazardous chemical initiators. Thehigh temperatures required for inverse vulcanization are also avoidedresulting in an improved safety profile. Density functional theorycalculations revealed a reversible "self-correcting"mechanism that ensures trisulfide linkages between monomer units.This control over sulfur rank is a new benchmark for high sulfur contentpolymers and creates opportunities to better understand the effectsof sulfur rank on polymer properties. Thermogravimetric analysis coupledwith mass spectrometry revealed the ability to recycle the polymerto the cyclic trisulfide monomer by thermal depolymerization. Thefeatured poly-(trisulfide) is an effective gold sorbent, with potentialapplications in mining and electronic waste recycling. A water-solublepoly-(trisulfide) containing a carboxylic acid group was also producedand found to be effective in the binding and recovery of copper fromaqueous media.