Morphology- and ion size-induced actuation of carbon nanotube architectures

Future adaptive applications require lightweight and stiff materials with high active strain but low energy consumption. A suitable combination of these properties is offered by carbon nanotube-based actuators. Papers made of carbon nanotubes (CNTs) are charged within an electrolyte, which results i...

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Bibliographic Details
Published in:International journal of smart and nano materials 2018-04, Vol.9 (2), p.111-134
Main Authors: Geier, Sebastian M., Mahrholz, Thorsten, Wierach, Peter, Sinapius, Michael
Format: Article
Language:English
Subjects:
Abbreviations
Actuation
actuation mechanism
actuators
Calomel electrode
Carbon
Carbon monoxide
carbon nanotube papers
Carbon nanotubes
Charging
Chemical vapor deposition
Electrical charging
Electrodes
Energy consumption
ion size
Ionic liquids
Mechanical properties
Modulus of elasticity
Multi wall carbon nanotubes
Nanotubes
Polydimethylsiloxane
Polymethyl methacrylate
Polypyrroles
Silicone resins
Single wall carbon nanotubes
Strain
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Summary:Future adaptive applications require lightweight and stiff materials with high active strain but low energy consumption. A suitable combination of these properties is offered by carbon nanotube-based actuators. Papers made of carbon nanotubes (CNTs) are charged within an electrolyte, which results in an electrical field forming a double-layer of ions at their surfaces and a deflection of the papers can be detected. Until now, there is no generally accepted theory for the actuation mechanism. This study focuses on the actuation mechanism of CNT papers, which represent architectures of randomly oriented CNTs. The samples are tested electrochemically in an in-plane set-up to detect the free strain. The elastic modulus of the CNT papers is analyzed in a tensile test facility. The influence of various ion sizes of water-based electrolytes is investigated.During the tests, four parameters that have a significant influence on the mechanical performance of CNT papers were identified: the test conditions, the electrical charging, the microstructure and the ion size. All of these influencing factors point to the mechanically weak inter-tube linking at which the actuation seems to take place. Quadratic voltage-strain correlation suggests a combination of electrostatic and volumetric effects as the possible reason for CNT paper actuation.Abbreviations: CNT: carbon nanotubes; CV: cyclic voltammetry; CVD: chemical vapor deposition; HiPCO: high pressure carbon monoxide; IL: ionic liquid; MWCNT: multi-walled carbon nanotube; MW: multi-walled; NHE: normal hydrogen electrode; PDMS: polydimethylsiloxane; PMMA: polymethylmethacrylate; PPy: polypyrrole; PVDF: polyvinylidenefluoride; SCE: saturated calomel electrode; SWCNT: single-walled carbon nanotube; SW: single-walled; 1M: one molar concentration
ISSN:1947-5411
1947-542X
DOI:10.1080/19475411.2018.1457573