Nature Chem. 5, 518–524 (2013)

Millions of tons of elemental sulphur are produced as a side product of petroleum and oil-refining processes each year, however, only a small proportion is recycled within the chemical industry. Now, Jeffrey Pyun and colleagues report a copolymerization reaction that uses a large excess of sulphur and smaller amounts of divinyl comonomers to make sulphur copolymers that are synthetically inexpensive but have practically valuable chemical and processing characteristics. The first step of this process, termed inverse vulcanization, involves dissolution of the divinylic styrenic comonomers in liquid sulphur. On heating, diradical sulphur species react with the comonomers to yield sulphur copolymers that form red glassy materials when cooled to room temperature. The copolymers are stable to depolymerization and can be processed in the melt to produce large-area films and more complicated micropatterned surfaces, using imprint lithography techniques. Moreover, the copolymers maintain the attractive electrochemical properties of elemental sulphur, and when incorporated as the active material of Li–S batteries show higher specific capacity compared with other polymer-based cathodes.