Actuation responsiveness, liquid electrolyte

The tri-layer configuration has been the most practical configuration for applications in wet and dry environments. However, one issue associated with them is the evaporation of the solvent if a conventional electrolyte is used and the actuator is not properly encapsulated. Of course, if an ionic liquid electrolyte is used, no need of encapsulation, no solvent will be used with a trade-off of a decrease in the speed of response and strain. 

Electrolytes typically used in ECDs, as in any other electrochemical cell, belong to four main classes aqueous electrolytes, organic liquid electrolytes, ionic liquids and solid polymer electrolytes. The adoption of so-called ionic liquids, such as ethyl ammonium nitrate ([EtNH3][N03]), l-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) or hexafluorophos-phate ([BMIMjfPFg]), can result in improved lifetime and response speed for electrochromics and actuators, and are best proposed being mixed with polymer or gel matrices. " ... 

Overall, within a proper operational range of 0.7 V the Ni-doped MFR IPMCs showed good paramagnetic characteristics and excellent electric responsive properties. This makes the developed MFR IPMCs attractive not only for actuator applications but also potentially for active damping applications. It is yet to be researched how the ionic liquids as potential electrolytes can improve the material to extend the operational voltage range. 

Fujiwara N, Asaka K, Nishimura Y et al (2000) Preparation of gold — solid polymer electrolyte composites as electric stimuli-responsive materials. Chem Mater 12(6) 1750-1754 Fukushima T, Asaka K, Kosaka A et al (2005) Fully plastic actuator through layer-by-layer casting with ionic-liquid-based bucky gel. Angew Chem hit Ed 44 2410-2413 Gao R, Wang D, Heflin JR et al (2012) Imidazolium sulfonate-containing pentablock copolymer-ionic liquid membranes for electroactive actuators. J Mater Chem 22 13473-13476 Gogotsi Y, Nikitin A, Ye H et al (2003) Nanoporous carbide-derived carbon with tunable pore size. Nat Mater 2(9) 591-594... 

Poly(ionic liquid) brushes with terminated ferrocene units acted similarly, while the interfacial resistance was probed by hexacyanoferrate [457]. Chemical and electrochemical switching of local pH at an electrode-grafted poly(vinyl pyridine) brush again allowed modulation of hexacyanoferrate chemistiy (Fig. 43) [458]. Octacyanomolybdate was used as catalyst for the oxidation of ascorbic acid [459]. Even heteropolyanions (Keggin ions) could be entrapped in polymer films electrochemicaUy [460]. Further, thermoresponsive or pH-responsive cationic copolymer films modulated the hexacyanoferrate or ferrocenedicarboxyUc acid electrochemistry by temperature or variatimi of pH and perchlorate concentration, respectively [461-463]. Besides these complexes with cationic polyelectrolyte films, electroactive cationic counterions (e.g., the europium couple) interacted with anionic networks [464]. Similarly, copper ions within a PAA matrix [367] allowed the construction of actuators [465]. Besides these binary systems (poly-electrolyte/electroactive counterions), multiresponsive electrode modification with an interpenetrating gel network of poly(acrylic) acid and poly(diethyl acrylamide) allowed the modulation of hexacyanoferrate electrochemistry [368]. 

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