Electrochemical activity of sulfur networks synthesized through RAFT polymerization

Abstract

Novel results concerning the inverse vulcanization of sulfur using reversible addition-fragmentation chain transfer (RAFT) polymerization are here reported. It is shown that RAFT polymerization can be used to carry out this cross-linking process, with the additional possibility to extend the reaction time from a few minutes as with classical free radical polymerization (FRP) to several hours. Higher control on viscosity and processability of the synthesized networks, as well as, the implementation of semibatch feed policies during cross-linking are important advantages of the RAFT process here explored comparatively to the FRP inverse vulcanization. Using cyclic voltammetry, it was assessed the electrochemical activity of the synthesized sulfur-rich polymer networks. It is shown that the fundamental electrochemical activity of the elemental sulfur was preserved in the produced materials. Testing of electrochemical cells assembled with lithium in the anode and different sulfur based materials in the cathode, including the synthesized RAFT networks, is also shown. The results here presented highlight the new opportunities introduced by reversible-deactivation radical polymerization mechanisms on the control of the synthesis process and in the design of such advanced materials and show also that many potential derivatizing possibilities can be achieved.

Tailoring Polysulfide Properties through Variations of Inverse Vulcanization

“…Most synthetic methods use temperatures well above the floor temperature of sulfur, 159 °C, with many using much higher temperatures, ∼185 °C. ,,, However, recent work has elucidated benefits to using lower reaction temperatures, including a lower risk of the production of hydrogen sulfide gas for reactions conducted below 135 °C. , Here, H 2 S was measured based on the formation of Ag 2 S precipitate formed when exposed to a solution of AgNO 3 . The resulting Ag 2 S was filtered and weighed.…”

Using conjugated system from natural sources for the synthesis of sulfur copolymers by bi‐function catalysts at mild temperatures

“…Recent researches developed sulfur copolymers using a large range of substances as the second monomers. Diisopropylbenzene, 13,17,32,33 divinylbenzene, 34–38 styrene, 39 myrcene, 40,41 D‐limonene, 42–44 dicyclopentadiene, 39,41,45,46 benzoxazines, 47–50 methacrylic acid, 51,52 4‐vinyl pyridine, 53,54 1‐(chloromethyl)‐4‐ethenyl‐benzene, 55,56 1,4‐dicyanobenzene, 57 span‐80, 58 1‐methylimidazole, 59 perillyl alcohol, 60 1,3‐phenylenediamine, 61 diallyl disulfide, 62 1,4‐diphenylbutadiyne, 63 eugenol, 42,64 and squalene 14 have successfully reacted with sulfur at 130–200°C to form stable polymers. The polymers from sulfur and diisopropylbenzene, dicyclopentadiene, myrcene, farnesol, or sorts of triglyceride oils 23,41,65–67 were confirmed their ability to absorb mercury.…”

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

“…Cleaving sulfur bonds requires very high temperatures (>159 °C) when sulfur is in the stable, eight-membered ring. , Current techniques typically use temperatures of ∼185 °C. ,− Inverse vulcanization yields extended sulfur chains stabilized by organic monomer cross-links and the presence of sulfur loops. , Within a linear arrangement, less energy is required to cleave S–S bonds . Mild temperatures of 90–100 °C have been used for postpolymerization curing, demonstrating the ability for further structural rearrangement. , Rheological studies provide further evidence of dynamic sulfur bonds in polysulfides at 100 °C for all polymers with a sulfur rank greater than n = 1 .…”