Sustainable Production of Ion‐Conductive Polyelectrolytes by Ultrafast Photopolymerization of Lithium, Sodium, and Potassium Salts/Amide‐Based Deep Eutectic Monomers

Abstract Herein, the photopolymerization of metal‐salt/amide‐based deep eutectic monomers (DEMs) derived from lithium, sodium, and potassium bis(trifluoromethanesulfonyl) imide (LiTFSI, NaTFSI, and KTFSI, respectively) is described. Three series of DEMs consisting of N ‐isopropyl acrylamide (NIPAM) and three different metal salts (LiTFSI, NaTFSI, and KTFSI) are tested at various molar ratios to identify suitable combinations. NIPAM/LiTFSI (1/0.2, 1/0.3, 1/0.4, and 1/0.5) and NIPAM/NaTFSI (1/0.2 and 1/0.3) are obtained as liquid DEMs by simple mixing under ambient conditions (≈25 °C in air), while NIPAM/KTFSI (1/0.1, 1/0.2, and 1/0.3) is obtained as a liquid DEM at 50 °C. The nature of the metal species and NIPAM/metal salt ratio affected the characteristic features of the DEMs and specific interactions. Ultrafast photopolymerization of NIPAM/metal salt DEMs is achieved using LED‐UV light, with nearly complete monomer conversion attained within 10 s. The mechanical and thermal properties of the polymerized DEMs (PDEMs) depended substantially on the metal species and NIPAM/metal salt ratio. P(NIPAM/0.2LiTFSI) with 20 wt.% succinonitrile (SN) serving as a plastic crystal exhibited the highest ionic conductivity (1.05 × 10 −4 S cm −1 at 55 °C), and P(NIPAM/0.2NaTFSI) and P(NIPAM/0.2KTFSI) also exhibited improved ionic conductivities of 4.19 × 10 −5 and 6.64 × 10 −5 S cm −1 , respectively, at 55 °C with 20 wt.% SN.