Electric-field alignment of aqueous multi-walled carbon nanotubes on microporous substrates

Remillard, E. Marielle; Zhang, Qiaoying; Sosina, Sobambo; Branson, Zach; Dasgupta, Tirthankar; Vecitis, Chad D.

doi:10.1016/j.carbon.2016.01.024

Cited by 27 publications

(14 citation statements)

References 44 publications

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“…When AC voltage was applied to the films, electrical anisotropy was confirmed. As the applied voltage increased from 0.5 kV p-p to 1.5 kV p-p , the resistance ratio increased regardless of MWCNT concentrations, thereby validating increased MWCNT alignment, which was also consistent with other studies [21,37,39]. By following the procedures described in section 4.3, the strain sensing performance of MWCNT-epoxy specimens was characterized.…”

Section: Resultssupporting

confidence: 86%

“…Gong et al [21] simulated CNT-based nanocomposites and presented that the model had higher conductivity along the CNT alignment direction than perpendicular to it. In addition, Ramillard et al [39] investigated electrical anisotropy of aligned MWCNT buckypaper by evaluating the log-ratio of electrical resistance and revealed that the log-ratio increased as MWCNTs were more aligned. Similarly, an electrical resistance ratio (r) was defined and calculated to evaluate the degree of CNT network alignment for the MWCNT-epoxy films tested in this work (equation (9)):…”

Section: Resultsmentioning

confidence: 99%

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Effect of carbon nanotube alignment on nanocomposite sensing performance

Lee

Zhi

Loh

2020

Mater. Res. Express

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The objective of this study is to derive a numerical model of carbon nanotube (CNT)-based thin films that accurately reflect their electrical and electromechanical performance as observed through experimental tests. Although nanocomposites based on CNTs dispersed in polymer matrices have been studied extensively, their nanocomposite properties vary depending on CNT orientations. This study aimed to explain how differences in nanocomposite behavior could be revealed by numerical models considering different CNT alignment conditions. First, a percolation-based thin film model was generated by randomly dispersing CNT elements in a predefined two-dimensional domain. The degree of CNT alignment in the film was controlled by limiting the CNT elements' maximum angle they make with respect to the film's longitudinal axis. Then, numerical simulations on CNT-based film models were conducted. Second, multi-walled carbon nanotube (MWCNT)-epoxy films were prepared via drop casting. Alternating current was applied to the MWCNT-epoxy mixture before curing to prepare films with different degrees of CNT alignment. The electrical and electromechanical properties of these specimens were characterized, and the results were compared with simulations. Good agreement between experiments and simulations was observed.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Effect of carbon nanotube alignment on nanocomposite sensing performance

Lee

Zhi

Loh

2020

Mater. Res. Express

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“…Strategies for aligning nanotubes have been pursued; however, many of these approaches have been developed without thin film transistors in mind. For example, the alignment of multiwalled carbon nanotubes has been demonstrated extensively; yet, multiwalled carbon nanotubes are semimetallic and thus are not suitable for transistors . Furthermore, techniques for aligning multiwalled carbon nanotubes are generally difficult to translate to aligning single‐walled carbon nanotubes, which are considerably smaller than multiwalled nanotubes.…”

Section: Introductionmentioning

confidence: 99%

“…[12] On the other hand, if the density of nanotubes is too low, then there are an insufficient number of charge conducting pathways, resulting in poor on-current and mobility. [21,22] Furthermore, techniques for aligning multiwalled carbon nanotubes are generally difficult to translate to aligning single-walled carbon nanotubes, which are considerably smaller than multiwalled nanotubes. [13] Driving nanotube alignment has been difficult, by itself, but concurrently realizing control over packing density, nanotube individualization, uniformity, and large-area scaling has been especially challenging.…”

mentioning

confidence: 99%

Substrate‐Wide Confined Shear Alignment of Carbon Nanotubes for Thin Film Transistors

Jinkins

Chan

Jacobberger

et al. 2018

Adv Elect Materials

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of highly aligned, individualized, electronics-grade semiconducting nanotubes are needed. These nanotubes must be uniformly deposited over large-area substrates at an intermediate linear packing density of 50-200 nanotubes µm −1 . [6,7] Alignment is important, as it decreases the number of resistive nanotube-nanotube junctions in the charge percolation pathway, thereby enabling high transistor drive current and mobility. [8,9] Moreover, nanotube individualization and control over packing density are important because the bundling and the formation of multilayers of tubes at high packing densities can result in transistors with low on/off conductance modulation ratio due to electrostatic screening. [10,11] Bundles and multilayers can also decrease on-current due to difficulties in forming low-resistance electrical contacts to tightly spaced nanotubes. [12] On the other hand, if the density of nanotubes is too low, then there are an insufficient number of charge conducting pathways, resulting in poor on-current and mobility. Individualization is also imperative in applications such as sensors, in which the nanotube surface area must be maximized to increase the number of accessible sites for analyte binding. [13] Driving nanotube alignment has been difficult, by itself, but concurrently realizing control over packing density, nanotube individualization, uniformity, and large-area scaling has been especially challenging. Most conventional approaches for depositing nanotubes onto substrates (e.g., spin, [14] blade, [15] and drop casting [16] ; spraying [17,18] ; and vacuum filtration [19,20] ) yield films of nanotubes that are randomly oriented. Strategies for aligning nanotubes have been pursued; however, many of these approaches have been developed without thin film transistors in mind. For example, the alignment of multiwalled carbon nanotubes has been demonstrated extensively; yet, multiwalled carbon nanotubes are semimetallic and thus are not suitable for transistors. [21,22] Furthermore, techniques for aligning multiwalled carbon nanotubes are generally difficult to translate to aligning single-walled carbon nanotubes, which are considerably smaller than multiwalled nanotubes. The alignment of nanotubes in polymer matrices has also received substantial attention, but this technique yields bulk composites rather than single layers of tubes on surfaces. [23][24][25] Likewise, recent work To exploit their charge transport properties in transistors, semiconducting carbon nanotubes must be assembled into aligned arrays comprised of individualized nanotubes at optimal packing densities. However, achieving this control on the wafer-scale is challenging. Here, solution-based shear in substrate-wide, confined channels is investigated to deposit continuous films of well-aligned, individualized, semiconducting nanotubes. Polymerwrapped nanotubes in organic ink are forced through sub-mm tall channels, generating shear up to 10 000 s −1 uniformly aligning nanotubes across substrates. The ink volume and concentration, channe...

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“…Induced polarization of SWCNTs is directly dependent on the strength of the electric field. Increase in the strength of the electric field can lead to enhancement in alignment and bundling of SWCNTs, which is due to the influence of neighboring particles on polarization . Besides, increase in concentration of SWCNTs can bring about SWCNTs attachment, and thus creation of SWCNT bundles with large length and diameter .…”

Section: Resultsmentioning

confidence: 99%

Electrified single‐walled carbon nanotube/epoxy nanocomposite via vacuum shock technique: Effect of alignment on electrical conductivity and electromagnetic interference shielding

et al. 2017

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Electrified and non‐electrified epoxy‐based nanocomposites holding highly and randomly aligned single‐walled carbon nanotube (SWCNT), respectively, were made by vacuum shock technique, where a DC electric field was used to align SWCNT. The alignment of SWCNTs in the electrified nanocomposites was verified via optical microscopy, SEM analysis, and Raman spectroscopy. Electrical characterization revealed that alignment of SWCNTs led to a significant improvement in electrical conductivity and electromagnetic interference shielding of the fabricated nanocomposites. For instance, the electrical conductivity of the electrified nanocomposites at 0.25 wt% and 0.60 wt% was 2.5 × 10−8 and 5.1 × 10−4 S·m−1, while the conductivity of non‐electrified nanocomposites was 1.1 × 10−11 and 5.6 × 10−5 S·m−1, respectively. With 3.0 mm thickness and 0.60 wt% SWCNT loading, the electrified and non‐electrified nanocomposites showed shielding effectiveness of 12.8 dB and 9.1 dB, respectively. These results revealed that electrification of SWCNT in epoxy‐based nanocomposites improved the level of conductive network formation, thereby enhancing electrical properties of the nanocomposites. POLYM. COMPOS., 39:E1139–E1148, 2018. © 2017 Society of Plastics Engineers

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Electric-field alignment of aqueous multi-walled carbon nanotubes on microporous substrates

Cited by 27 publications

References 44 publications

Effect of carbon nanotube alignment on nanocomposite sensing performance

Effect of carbon nanotube alignment on nanocomposite sensing performance

Substrate‐Wide Confined Shear Alignment of Carbon Nanotubes for Thin Film Transistors

Electrified single‐walled carbon nanotube/epoxy nanocomposite via vacuum shock technique: Effect of alignment on electrical conductivity and electromagnetic interference shielding

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