Solvation‐Driven Actuation of Anion‐Exchange Membranes

Ulbricht, Nicco; Boldini, Alain; Bae, Chulsung; Wallmersperger, Thomas; Porfiri, Maurizio

doi:10.1002/admi.202200888

Cited by 5 publications

(6 citation statements)

References 56 publications

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“…Positive bending directions are defined in the direction opposite to the applied electric field, consistent with previous experiments. 16 Independent of the used external solution and counterion, all membranes showed a bending response in the direction opposite to the applied electrical field. This is in agreement with the phenomenological actuation mechanism described in Section 2, thus pointing to solvation as main driver of actuation.…”

Section: Resultsmentioning

confidence: 97%

“…11 Besides a few exception, [12][13][14][15] the technical literature focuses on the use of cation-exchange membranes as soft actuators. In a recent effort, 16 we provided evidence for the possibility of contactless actuation in anion-exchange membranes. This paper provides a summary of the main experimental findings of our previous study, focusing on a subset of experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

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Experimental characterization of actuation of anion-exchange membranes in salt solution

Ulbricht

Boldini

Bae

et al. 2023

Electroactive Polymer Actuators and Devices (EAPAD) XXV

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Besides their use in separation and filtration processes, ion-exchange membranes have been adopted as electroactive polymer actuators in soft robotics and biomedical engineering, due to their unique coupling between electrochemistry and mechanics. Actuation is generated by the asymmetry in cations and anions transport, as one of the two species is bonded to the membrane backbone, whereas the other can move throughout the membrane. Typically, electrodes are plated on the membrane to enable application of an external electric field. A new, promising contactless actuation configuration for underwater applications consists of immersing a bare membrane in an electrolyte solution, between external electrodes. When an electric field is imposed across the electrodes, a macroscopic bending deformation is observed. Despite major advances in understanding the actuation of cation-exchange membranes (with fixed anions), the actuation of anion-exchange membranes (with fixed cations) is an almost untapped field. In this work, we experimentally investigate the contactless actuation of anion-exchange membranes. In the experiments, we systematically vary the anions in the external solution and inside the membrane, to unravel their effects on membrane actuation. In all tested combinations, the membrane always bends in the opposite direction compared to cation-exchange membranes. Additionally, we find a prominent influence of the external anions on the actuation strength, consistent with previous theories that attribute actuation to solvation effects. Our results help shade light on the chemoelectromechanics of anion-exchange membranes, toward their increase adoption as soft actuators.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Experimental characterization of actuation of anion-exchange membranes in salt solution

Ulbricht

Boldini

Bae

et al. 2023

Electroactive Polymer Actuators and Devices (EAPAD) XXV

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“…[57] These results would suggest that the variability in performance of composites of anion-exchange membranes could be even higher, due to their lower stability. Although experimental backing to this claim is not available at this time, recent experiments from our group on the contactless actuation of anion- exchange membranes [58] offer partial support to this expectation. Therein, we determined that the actuation response of bare p-TPN1 membranes in a solution, under an applied electric voltage, was much more variable across samples than cation-exchange membranes.…”

Section: Discussionmentioning

confidence: 99%

Plating of Ion‐Exchange Membranes: A Molecular Dynamics Study

Truszkowska

Boldini

Porfiri

2022

Advcd Theory and Sims

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Electroless plating of membranes offers a viable pathway to create flexible electrodes for soft sensors and actuators, as well as flexible electronics and batteries. Ionic polymer metal composites are a promising class of active materials, realized through electroless plating of ion‐exchange membranes. The plating and electrode‐membrane interface play a key role on their performance, but computational tools to inform the selection of the plating material and optimize the plating process are currently lacking. Here, this gap is filled through the study of the electrode‐membrane interface in different types of ion‐exchange membranes via molecular dynamics simulations. Both commercially available cation‐ and research‐grade anion‐exchange membranes are studied here. For platinum coating, it is predicted that cation‐exchange membranes will have a superior interface than anion‐exchange membranes, in terms of metal penetration into the membrane, reliability of actuation performance, and interface stability. The results are in line with previous endeavors documenting the higher stability of the interface for cation‐ than for anion‐exchange membranes, easier plating processes, and better electrochemical performance when working with cation‐exchange membranes. The proposed computational framework offers a versatile environment for testing different types of coatings for specific membranes, toward optimizing the performance of electrochemical devices with plated flexible electrodes.

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“…[10][11][12] In addition to IPMCs, recent efforts have developed new contactless actuators based on bare ionic membranes. [13][14][15][16] The coupling between electrochemistry and mechanics in ionic membranes is related to their peculiar microstructure, which also causes their permselectivity. Ionic membranes are porous, polymeric materials, permeated with a solution of mobile ionic species.…”

Section: Introductionmentioning

confidence: 99%