High performance polymer actuator based on carbon nanotube-ionic liquid gel: Effect of ionic liquid

Abstract In this study, we investigated a dependence of anionic species of ionic liquids (ILs) (IL: perfluoroalkyltrifluoroborate anions ([C n F 2 n +1 BF 3 ] − ( n  = 0, 1, 2) and bis(perfluoroalkylsulfonyl)imide anions ([(C m F 2 m +1 SO 2 )(C n F 2 n +1 SO 2 )N] − ( m , n  = 0, 1, 2)) on electrochemical and electromechanical properties. 1-Ethyl-3-methylimidazolium (EMI + ) was selected as a cation for ILs. 1-Ethyl-3-methylimidazolium trifluoromethyltrifluoroborate (EMI[CF 3 BF 3 ]), 1-ethyl-3-methylimidazolium pentafluoroethyltrifluoroborate (EMI[CF 3 CF 2 BF 3 ]), 1-ethyl-3-methylimidazolium fluorosulfonyl(trifluoromethylsulfonyl)imide (EMI[FTA]) and 1-ethyl-3-methylimidazolium pentafluoroethylsulfonyl(trifluoromethylsulfonyl)imide (EMI[C 1 C 2 ]) were synthesized according to the literatures. The generated strains of the bucky-gel electrodes of the actuators containing EMI[CF 3 BF 3 ] (in the high frequency range: 10–0.5 Hz) and EMI[CF 3 CF 2 BF 3 ] (in the high frequency range of 1–0.5 Hz) are larger than that containing EMI[BF 4 ] (that is to say the quick response). For low frequencies (0.1–0.005 Hz), the generated strain containing EMI[CF 3 CF 2 BF 3 ] was larger than those containing other ILs (EMI[C n F 2 n +1 BF 3 ] ( n  = 0, 1) and EMI[(C m F 2 m +1 SO 2 )(C n F 2 n +1 SO 2 )N] ( m , n  = 0, 1, 2)). The Young's modulus of actuators containing EMI[CF 3 BF 3 ] and EMI[CF 3 CF 2 BF 3 ] were 145 and 110 MPa, respectively. The melting points of EMI[CF 3 BF 3 ] and EMI[CF 3 CF 2 BF 3 ] are lower than that of EMI[BF 4 ]. Therefore, trifluoromethyltrifluoroborate ([CF 3 BF 3 ] − ) and pentafluoroethyltrifluoroborate ([CF 3 CF 2 BF 3 ] − ) anions performed much better as the actuator using the polymer-supported bucky-gel electrode containing the IL. These results are considered to be the actuator enough to apply actual applications (e.g. tactile display).

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