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 3BF 3]), 1-ethyl-3-methylimidazolium pentafluoroethyltrifluoroborate (EMI[CF 3CF 2BF 3]), 1-ethyl-3-methylimidazolium fluorosulfonyl(trifluoromethylsulfonyl)imide (EMI[FTA]) and 1-ethyl-3-methylimidazolium pentafluoroethylsulfonyl(trifluoromethylsulfonyl)imide (EMI[C 1C 2]) were synthesized according to the literatures. The generated strains of the bucky-gel electrodes of the actuators containing EMI[CF 3BF 3] (in the high frequency range: 10–0.5 Hz) and EMI[CF 3CF 2BF 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 3CF 2BF 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 3BF 3] and EMI[CF 3CF 2BF 3] were 145 and 110 MPa, respectively. The melting points of EMI[CF 3BF 3] and EMI[CF 3CF 2BF 3] are lower than that of EMI[BF 4]. Therefore, trifluoromethyltrifluoroborate ([CF 3BF 3] −) and pentafluoroethyltrifluoroborate ([CF 3CF 2BF 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).