Efficient self healable blended cationic and anionic poly(ionic liquids) under ambient conditions

Abstract

AbstractPoly(ionic liquid)‐based self‐healable electrolytes are getting tremendous attention owing to their quick self‐healing ability at ambient conditions without external stimulus, prominent safety, high mechanical strength, appreciably good conductivity, and no electrolyte leakage. Ionic interactions are much stronger and more dynamic, capable of imparting faster healing ability to the electrolyte. To exploit ionic interactions and non‐covalent hydrogen bonding simultaneously for faster self‐healing at ambient conditions. In the present work, free radical promoted copolymerization of 3‐methyl‐1‐vinylimidazolium iodide and sodium 4‐vinyl benzenesulfonate (VMeImI/SS) with poly(ethylene glycol) methyl ether acrylate and ureidopyrimidinone methacrylate to obtain cationic poly (PEG‐UPy‐Im) and anionic poly (PEG‐UPy‐SS) poly ionic liquid (PIL), respectively, as polymer electrolytes (PEs) have been achieved. The complete structural analysis of the copolymers by FTIR, 1H NMR, 13C NMR, DOSY‐NMR, and GPC was done. The ionic conductivity and self‐healing properties of the synthesized PEs, poly (PEG‐UPy‐Im) and poly (PEG‐UPy‐SS) were investigated, which gave encouraging results. For further enhancement of hydrogen bonding and ionic interactions, poly (PEG‐UPy‐Im) and poly (PEG‐UPy‐SS) were blended in the ratio of 1:1, referred to as poly (Im‐SS), a binary blend, as a self‐healable oppositely charged polyelectrolyte. Poly(Im‐SS) exhibited self‐healing behavior in 15 min and 5 min at 25 and 60°C, respectively, without any external stimulus. Poly(Im‐SS) also exhibited exceptionally high ionic conductivity of 2.04 × 10−5 and 11.48 × 10−5 Scm−1 at 30 and 80°C, respectively. This unique approach of blending two oppositely charged PEs to create a binary blend has improved ionic conductivity and self‐healing capabilities. Because a poly‐ionic network forms in poly(Im‐SS) as a binary blend, the physical and chemical properties in terms of mechanical and thermal stability as well as water contact angle point to a synergistic effect of ion–ion, ion–dipole, and quadruple Hbonding. Thus, the designed copolymer electrolytes and their blend, present a new perspective to develop innovative and rapid self‐healable polyelectrolytes with significant ionic conductivity for advanced electrochemical devices such as fuel cells, batteries, and supercapacitors.