Polymer Actuators Using Ion-Gel Electrolytes Prepared by Self-Assembly of ABA-Triblock Copolymers

Abstract

Well-defined ABA-triblock copolymers, polystyreneblock-poly(methyl methacrylate)-block-polystyrene (SMS), which have two different polystyrene (PSt) weight fractions (f PSt ), were synthesized by successive atom-transfer radical polymerizations. Ion gels consisting of SMS and an ionic liquid, (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [C 2 mim][NTf 2 ]), were prepared using the cosolvent evaporation method with tetrahydrofuran. Atomic force microscope images of the ion gels indicated that PSt is phase-separated to form sphere domains that serve as physical cross-linking points because PSt is not compatible with [C 2 mim][NTf 2 ], while a continuous poly(methyl methacrylate) (PMMA) phase with dissolved [C 2 mim][NTf 2 ] is formed to serve as ion conduction paths. Accordingly, the ion gels are formed by the self-assembly of SMS and the preferential dissolution of [C 2 mim]-[NTf 2 ] into the PMMA phase. The viscoelastic properties of the gels can be easily controlled by changing f PSt in SMS and [C 2 mim][NTf 2 ] concentration in the ion gels. The ion gels that exhibit high ionic conductivities (>10 −3 S cm −1 ) at room temperature were used as an electrolyte of an ionic polymer actuator, which has a trilaminar structure consisting of the ion-gel electrolyte sandwiched between two composite carbon electrodes containing high-surface-area activated carbon powders. By applying low voltages (<3.0 V) to the electrodes, the actuator exhibited a soft bending motion toward the anodic side.

Fast low-voltage electroactive actuators using nanostructured polymer electrolytes

“…In fact, research on actuators comprising ionic liquids has commonly used a few conventional polymers 25,26 , thus impeding major advances in ionic polymer actuators, which essentially require the optimization of ion transport characteristics and mechanical properties of the polymer layer. In this respect, the use of microphase-separated polymers in actuators has recently been proposed as a promising means to elevate the actuator performance 7,10,[33][34][35][36][37][38][39][40][41] . For instance, Long et al 34,35 , Spontak et al 7,36,37 , Colby et al 38,39 and Watanabe et al 10,40 , have employed self-assembled block copolymers in actuators and improved electromechanical deformation has been reported, compared with that of several conventional polymers lacking organization.…”

Physical and Electrochemical Investigations into Blended Electrolytes Containing a Glyme Solvent and Two Bis{(trifluoromethyl)sulfonyl}imide-Based Ionic Liquids

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Furthermore, the high (electro)chemical stabilities and non-volatilities exhibited by many IL structures provides interesting electrolyte media for electrochemical gas sensors (e.g. for O 2 , [16][17][18][19] CO 2 ,20,21 NO 2 22 ) where traditional solvents are prone to evaporation leading to device failure, and also for electromechanical actuator, [23][24][25] and electrodeposition applications. [26][27][28] Nevertheless, while the properties of ILs are dependent on the virtually unlimited combinations of different cation and anion structures, the attractive features are generally coupled with sluggish transport properties relative to conventional electrolytes based on either aqueous or organic solvents.…”

Design and Materialization of Ionic Liquids Based on an Understanding of Their Fundamental Properties

“…33 Herein, I discuss the application of an ion gel to ionic polymer actuators. [38][39][40][41][42] As a material for manufacturing polymer actuators with bio-mimetic soft motion, electronic and ionic polymer actuators have been proposed and applied to manipulators and robotic devices. Ionic polymer actuators driven by migration or diffusion of ions can achieve relatively large deformations in response to the application of low voltages.…”

“…4). 39 2 ] is formed and serves as an ion conduction pathway. These structures have been observed in atomic force microscope phase images of the ion gels (Fig.…”