INTRODUCTION: Sulfur-rich copolymers containing S-S bonds have many useful properties such as redox activity, 1, 2 affinity for heavy metals and precious metals, and a high refractive index of relevance to optics applications. Studies on the synthesis and application of polysulfide-containing polymers have been spurred by the advent of inverse vulcanization. Introduced by Pyun and co-workers in 2013, inverse vulcanization refers to the bulk copolymerization of elemental sulfur and an organic comonomer containing one or more carboncarbon double or triple bonds. In this reaction, molten sulfur is the monomer, initiator, and solvent. At approximately 160 ºC, sulfur undergoes ring-opening polymerization to form polymeric sulfur with thiyl radical end groups (Fig. ). These radicals can then add to the alkene or alkyne of the organic monomer, followed by further reaction with sulfur or other polysulfides in the reaction mixture. Termination, for instance by radical recombination, provides the polymer product. In contrast to classic vulcanization in which small amounts of sulfur are used to crosslink a preformed organic polymer, inverse vulcanization uses organic monomers to crosslink a polysulfide formed in situ. fertilizers, and recyclable machine components, in addition to other applications recently reviewed. Despite the many useful polymers accessible by inverse vulcanization, this polymerization method does have limitations. For instance, the reaction typically requires high temperatures to form molten sulfur and induce its ring-opening polymerization (typically 160 ºC or higher). The high temperature may not be compatible with many organic comonomers and introduce high energy costs and safety concerns. The reaction is also frequently complicated by the immiscibility of many organic comonomers with molten sulfur, which can lead to inefficient reactions and unwanted phase separation in the product. Furthermore, the exothermic nature of the inverse vulcanization can lead to runaway reactions and formation of hazardous byproducts such as hydrogen sulfide or malodorous thiols. In terms of polymer structure, inverse vulcanization provides limited control over sulfur rank (the number of sulfur atoms between each carbon atom in the organic monomer), molecular weight, and stereochemistry of the C-S bonds. Such control is important because sulfur rank influences the strength of the S-S bonds, which-along with molecular weight and stereochemistrywill influence the physical properties of these polymers.