Synthesis of Poly(TEMPO‐Substituted Glycidyl Ether) by Utilizing t‐BuOK/18‐Crown‐6 for an Organic Cathode‐Active Material

Abstract

Summary: A nitroxide radical-substituted polyether, poly(TEMPO-substituted glycidyl ether) (PTGE), was synthesized using a potassium tert-butoxide/18-crown-6 initiator. The presence of 18-crown-6 effected significant improvement in the reactivity of the chain end, thus allowing the polymerization to proceed at moderate temperatures to suppress the deactivation of the pendant nitroxide group. A high molecular-weight polyether with a theoretical radical concentration was first obtained in high yield. Charging and discharging cyclability was much improved by cross-linking, which helped the electrode-active material stay on a current collector during the electrolysis. The polymer/vapor-grown carbon nanofiber composite electrode exhibited a redox capacity comparable to the formula weightbased theoretical density over 10 3 cycles and fast charging/discharging capability up to a rate of 60 C which corresponded to full charging and discharging in 60 s. The redox capacity was almost maintained for a composite layer with a remarkably high polymer ratio of 90 %, which demonstrated the presence of effective percolation network of the carbon nanofiber due likely to the affinity of the polyether to the carbon material.

TEMPO‐Substituted Poly(ethylene sulfide) for Solid‐State Electro‐Chemical Charge Storage

“…[ 18,21 ] The experimental molecular weights of P3 were lower than expected (Runs 1 and 1′), which we attribute to chain transfer reactions resulting from the harsh reaction conditions. [ 18,21 ]…”

“…The high experimental yield of the polymers (>90%) was achieved because of the living‐like property of the polymerization. [ 21 ] A high spin concentration of radicals (>90%) was estimated using superconducting quantum interference device (SQUID); this value corresponded to a charge/discharge capacity of around 100 mAh g −1 , and indicated a negligible occurrence of nitroxide side reactions.…”

“…As soon as potassium tert ‐butoxide ( t ‐BuOK) was added to this reaction mixture, insoluble polymer P4 was generated (Run 4, Table 1), whereas the polymerization did not proceed to a sufficient extent with the glycidyl without adding a crown ether. [ 18,21 ] The use of a weaker sodium base ( t ‐BuONa) gave a soluble polythioether with a tenfold higher molecular weight and high polydispersity (1.7, Run 5, Table 1). The relatively high nucleophilicity of thiolates as the active species, compared to that of alkoxides, [ 22 ] was considered key to the higher reactivity of the episulfides.…”

A Methoxyamine‐Protecting Group for Organic Radical Battery Materials—An Alternative Approach

“…Polymers with pendant nitroxide moieties have previously been synthesized by various polymerization techniques, including ring‐opening metathesis polymerization (ROMP), ring‐opening polymerization, anionic, group transfer, and radical polymerization . While radical polymerization is generally the most widely employed polymerization technique, owing to its ease of use and straight forward reaction conditions, nitroxide‐bearing monomers cannot be directly polymerized because of the nitroxide's radical scavenging nature and inhibition effect on free radical chain propagation.…”

Synthesis of Novel Nitroxide Radical Polymer Materials for Imaging and Energy Storage Applications

“…The same authors later optimized the reaction conditions for the AROP of TGE 7. 178 By employing 18-crown-6 as an activating agent for the initiator and living chain end, in a 3-fold excess with regards to the initiator, a more efficient polymerization was possible. Lowering of the reaction temperature to 40 ˚C suppressed deactivating side reactions with the nitroxide moieties, allowing high yields, molecular weights close to the theoretical value, and full radical functionality.…”