Polymerizations with elemental sulfur: A novel route to high sulfur content polymers for sustainability, energy and defense

Abstract

Recent developments in the polymerizations of elemental sulfur (S 8 ) to prepare high sulfur content polymers are reviewed. While the homopolymerization of S 8 via ring-opening processes to prepare high molar mass polymeric sulfur has long been known, this form of polymeric sulfur is chemically unstable and depolymerizes back to S 8 . In the current report, we discuss the background into the production of sulfur via petroleum refining and the challenges associated with utilizing S 8 as a chemical reagent for materials synthesis. To circumvent these long standing challenges in working with sulfur, the use of S 8 as a reaction medium and comonomer in a process termed, inverse vulcanization, was developed to prepare chemically stable and processable sulfur copolymers. Furthermore, access to polymeric materials with a very high content of sulfur-sulfur (S-S) bonds enabled for the first time the creation of materials with useful (electro)chemical and optical properties which are reviewed for use in Li-S batteries, IR imaging technology and self-healing materials.

Functional Polymeric Materials Based on Main‐Group Elements

“…An exception is the spontaneous ring-opening of arsenomethane,( MeAs) 5 (16), which produces an insoluble purple solid with semiconducting properties.E xperimental and theoretical studies attributed the low solubility to ab ackbone structure consisting of aladder of two stacked poly(methylarsine) linear chains (19,Scheme 3,top). [27] In as eminal work, [28] they described af acile method for preparing copolymers 24 with 1,3-diisopropenylbenzene (DIB), also termed CHIPS (chalcogenide hybrid inorganic/ organic polymers), achieving up to 90 wt %ofScontent. [25] Ther esulting soluble polymers have ap erfectly alternating sequence with [ER À CR 1 = CH] n repeat units (20,E= P, As or Sb;R= Ph or Me,R 1 = aryl or alkyl, Scheme 3, bottom) and preferentially adopt trans conformations.T he P-phenyl analogues are typically prepared by anionic ROP of phosphirenes (21,R 2 = Me) and obtained in somewhat higher yields.…”

Infrared Fingerprint Engineering: A Molecular‐Design Approach to Long‐Wave Infrared Transparency with Polymeric Materials

“…Thes ynthesis of the NBD2 monomer was prepared according to literature procedures [14] and was then subjected to inverse vulcanization [15][16][17][18] with liquid sulfur (T = 130-160 8 8C) to afford poly(sulfur-random-NBD2)(poly(S-r-NBD2)), at two different feed ratios (70-wt %S /30-wt % NBD2 &5 0-wt %S /50-wt %N BD2). Copolymerization of these comonomers afforded amorphous,yellow,g lassy crosslinked networks.Structural characterization of these thermosets was done using 13 CC P-MAS solid-state NMR spectroscopy (Figure 3b), which confirmed that the norbornyl skeletal framework remained intact after polymerization, as indicated by the upfield resonances at 44 and 48 ppm from methylene and methine protons from NBD2.…”

Sulfur and Its Role In Modern Materials Science

“…[13,19] In this process,s ulfur served as the backbone material, and aromatic carbon comonomers were bound to sulfur chains to form stable polymer complexes.T he inverse vulcanization method takes advantage of sulfursr ing-opening and chain-forming tendencies at elevated temperatures by binding divinyl molecules to the sulfur radicals that form when sulfursS 8 rings open ( Figure 3). [13,19] In this process,s ulfur served as the backbone material, and aromatic carbon comonomers were bound to sulfur chains to form stable polymer complexes.T he inverse vulcanization method takes advantage of sulfursr ing-opening and chain-forming tendencies at elevated temperatures by binding divinyl molecules to the sulfur radicals that form when sulfursS 8 rings open ( Figure 3).…”