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

Abstract

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 nanotubebased 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 setup 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.

Carbon Nanostructures for Actuators: An Overview of Recent Developments

“…The first actuation using CNTs was reported by Baughman et al [54], where a sheet of aggregated SWCNTs named buckypaper achieved a displacement of 0.12% under a square wave potential of ±0.5 V. A few years later, Roth et al [55] reported electrochemical actuation on a single CNT and a maximum isometric stress of up to 25 MPa [56]. Many studies have been devoted to investigating the relationship between electrical input and the actuations of CNTs [57,58], showing how the aspect ratio is an unneglectable factor together with the network properties of CNTs [49,59,60].…”

Smart structures, materials and nano technology in engineering

“…The present IJSNM special issue spans volume 9's issue 1 [1][2][3][4] and issue 2 [5][6][7][8]; it contains 8 papers [1][2][3][4][5][6][7][8] that were extended and revised (some of them twice) according to 3 anonymous and independent peer reviewers' reports. They were spontaneously submitted following an open call to the participants of the joint 8th SMART and 6th SMN held in Madrid (Spain) from 5 to 8 June 2017.…”

“…It was closed by a technical visit to a 'design and manufacturing of aero-structures and components' supplier of renowned international (multi-national) aircraft manufacturers. Hereafter are briefly described the 8 papers of the present IJSNM special issue spanning volume 9's issue 1 [1][2][3][4] and issue 2 [5][6][7][8].…”

“…The 7th paper [7], presented in above MS05, describes an approach to determine shunt circuits parameters for vibration damping. The last (8th) contribution [8] is a sample of the synergy between SMART and SMN joined events as it discusses morphology-and ion-size induced actuation of Carbon Nano Tube (CNT) architectures.…”

“…As a closure, we are very thankful to the authors for their very interesting contributions and to the reviewers for their meticulous reports. Besides, the organizers of SMART and SMN 2017 are very thankful to the editor-in-chief, Professor Jinsong Leng, and to the publisher, Sage Publications, for their supports to these events by dedicating the present special issue (spanning volume 9's issue 1 [1][2][3][4] and issue 2 [5][6][7][8]) to sample contributions from those presented therein and by publishing it in open access format with weaved Articles Processing Charges (APC).…”