Dynamic Sulfur Bonds Initiate Polymerization of Vinyl and Allyl Ethers at Mild Temperatures

Abstract

Elemental sulfur (S8) is produced in abundance during petroleum refinement, generating millions of tons of waste. Inverse vulcanization utilizes this waste as a feedstock to create new materials. Heating S8 above 159 °C initiates ring-opening, forming radicals that react with difunctional monomers to create polysulfides. High temperature requirements limit the types of monomers that can be incorporated by inverse vulcanization. However, cleaving the linear sulfur chains present in the polysulfides requires less energy. Here, poly(S–divinylbenzene) with varied sulfur contents has been synthesized to act as a prepolymer capable of radical formation at much lower temperatures (90 °C). Dynamic sulfur bonds initiate polymerization with a family of vinylic and allylic ethers. Terpolymers were characterized by NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry to examine the impact on structure and physical properties. This method expands on inverse vulcanized polymers to create a mild, solvent-free route to polysulfide synthesis.