Ionic polymer actuators using poly(ionic liquid) electrolytes

Abstract

In this work, poly(ionic liquid) (polyIL) polymer electrolytes were prepared by the free radical copolymerization of IL monomers with a plasticizing monomer having poly(ethylene glycol) (PEG) side chain. The IL monomers, i.e., the polycation and polyanion precursors, were 1-[(3-methacryloyloxy)propyl]-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C 3 mim-MA][TFSA]) and 1-methyl-3-propylimidazolium N-[3-(methacryloyloxy)propylsulfonyl]-N-(trifluoromethanesulfonyl)amide ([C 3 mim][TFSA-MA]), respectively. The ionic conductivities of the polyIL polymer electrolytes increased with a decrease in the weight fraction of the ionic monomer owing to the plasticizing effect of the PEG side chain, whereas the mechanical strength simultaneously decreased due to a lowering in the glass transition temperature of the electrolytes. The ionic conductivities of the electrolytes were 10 −6-10 −7 S cm −1 at room temperature. Ionic polymer actuators were fabricated using the polyILs as an electrolyte layer by sandwiching the electrolyte membrane with two carbon electrodes. The displacement behavior depended entirely on the fixed charge on the polymer chain.

Ionic Liquid Electrolytes for Electrochemical Energy Storage Devices

“…In addition, the tunable polarity of ILs prevents the adverse dissolution of active materials, such as water [ 37 ], and various structures of ILs are proposed by simple synthesis [ 38 ]. Because of these properties, ILs for various electrochemical devices, such as SCs, FCs, LIBs, solar cells, and actuators, have been researched [ 37 , 41 , 42 , 43 , 44 , 45 , 46 ]. ILs consist of a large organic cation, such as imidazolium, ammonium, and pyrrolidinium, with a variety of anions.…”

Electroactive Polymers Obtained by Conventional and Non-Conventional Technologies

“…PILs/IL-based polymers conjugate the properties of the ionic liquids (e.g., ionic conductivity, negligible vapor pressure, and thermal stability) with those from polymers (e.g., functionalization, viscoelastic properties, and 3D structure) [ 50 ]. Recently, IL-based copolymers ionic EAPs were developed for soft actuators and promising tissue engineering scaffolds applications [ 12 , 51 ].…”

“…Kokubo et al developed IL-based copolymers ionic polymer actuators and studied the influence of polyelectrolyte structure (polycationic or polyanionic) in the bending performance [ 51 ]. Crosslinked polymer electrolytes were prepared by free-radical copolymerization of cationic IL monomer (1-[(3-methacryloyloxy)propyl]-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide, [PMIm-MA][TFSA]) or anionic IL monomer (1-methyl-3-propylimidazolium N-[3-(methacryloyloxy)propylsulfonyl]-N-(trifluoromethanesulfonyl)amide, [PMIm][TFSA-MA]) with poly(ethylene glycol) methyl ether methacrylate (PEGMEN) plasticizer, crosslinked by ethylene glycol dimethacrylate (EGDMA, 2 mol% of the total monomers).…”

“…Moreover, polyanions presented higher (~1.3x greater) bending displacement than polycations due to differences in the size of counter ions of each polyelectrolyte. Polyanion’s counter ions (PMIm+) were smaller (~1.2x smaller) than polycation’s (TFSA-), which facilitated its diffusion through the polymeric network in response to an electrical stimulus resulting in higher ionic conductivity and also, greater electromechanical displacements [ 51 ].…”

Conductivity–modulus–Tg relationships in solvent‐free, single lithium ion conducting network electrolytes

“…Polymer networks containing ionic species have received attention as functional materials in liquid/gas separations, [9][10][11][12][13][14][15] soft actuators, [16][17][18][19][20] ion exchange membranes, [21][22][23][24][25] and electrolytes for energy storage. [26][27][28][29][30][31][32][33][34][35] In the context of lithium conduction, polyethylene oxide (PEO) networks with added lithium salts have been investigated and it was shown that covalent crosslinking can significantly reduce the crystallinity and increase the ionic conductivity.…”