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

Abstract

Elemental sulfur (S 8 ) 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 S 8 above 159 °C initiates ringopening, 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.

Valorization of Lignin as a Sustainable Component of Structural Materials and Composites: Advances from 2011 to 2019

“…In 2013, Pyun reported an intriguing method for exploiting this waste sulfur as a component of copolymers by its reaction with olefins via a process called inverse vulcanization [50]. Although elemental sulfur itself is quite brittle, durable materials can be obtained for the copolymers comprising up to 90 wt.% sulfur [51][52][53][54]. These efforts have employed a wide range of starting materials including cellulose, lignin, amino acids, terpenoids, algae acids, polystyrene derivatives, and other olefins [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70].…”

Crosslinker Copolymerization for Property Control in Inverse Vulcanization

“…[29] Similarly,i nitial reaction of sulfur with divinylb enzene allows later reaction with 1,4-cyclohexanedimethanol divinyl ether which, had it been reacted with sulfur directly, would have required ar eactiont emperature higher than its boilingp oint. [30] In at hird study,D iez et al produced terpolymers of sulfur and divinyl benzene (DVB) with either DIB or styrene (STY). [28] They showed that by adding asecond crosslinker, the ductility can be influenced.…”

Sequential crosslinking for mechanical property development in high sulfur content composites

“…The polymeric sulfur chains also undergo S S bond metathesis (via radicals) above 90 C. This S S metathesis allows for innovative lower-temperature processing approaches for HSMs. [32][33][34][35] Polymeric sulfur domains can reform following their rearrangement by metathesis when the material is cooled back to room temperature, provided that the supporting network is intact , allowing materials to be reshaped or thermally healed. [6,22,26,[36][37][38][39][40] Two types of S S bonds are typically present in these materials: those in polymeric/oligomeric catenates that undergo metathesis at temperatures as low as 90 C and those in cyclic S 8 allotropes that generally require heating to above 159 C to undergo metathesis.…”