Aggregation and Self-Assembly of Amphiphilic Block Copolymers in Aqueous Dispersions of Carbon Nanotubes

Shvartzman-Cohen, Rina; Florent, Marc; Goldfarb, Daniella; Szleifer, Igal; Yerushalmi‐Rozen, Rachel

doi:10.1021/la703782g

Cited by 71 publications

(84 citation statements)

References 43 publications

(100 reference statements)

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“…Because of its amphiphilic characteristic, Pluronic can disperse nanotubes in aqueous solutions and achieving steric stabilization, which prevents agglomeration of nanotubes [43]. Shvartzman-Cohen et al [44] demonstrated that SWCNTs can be dispersed in Pluronic solution well below the critical micellar concentration and critical micellar temperature. Zhao et al [36] found that MWCNT-Pluronic dispersions remained stable for weeks.…”

Section: Nanocomposite Fabricationmentioning

confidence: 99%

Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations

Lee¹,

Loh²

2017

Nanotechnology

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Carbon nanotubes can be randomly deposited in polymer thin film matrices to form nanocomposite strain sensors. However, a computational framework that enables the direct design of these nanocomposite thin films is still lacking. The objective of this study is to derive an experimentally validated and two-dimensional numerical model of carbon nanotube-based thin film strain sensors. This study consisted of two parts. First, multi-walled carbon nanotube (MWCNT)-Pluronic strain sensors were fabricated using vacuum filtration, and their physical, electrical, and electromechanical properties were evaluated. Second, scanning electron microscope images of the films were used for identifying topological features of the percolated MWCNT network, where the information obtained was then utilized for developing the numerical model. Validation of the numerical model was achieved by ensuring that the area ratios (of MWCNTs relative to the polymer matrix) were equivalent for both the experimental and modeled cases. Strain sensing behavior of the percolation-based model was simulated and then compared to experimental test results.

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Section: Nanocomposite Fabricationmentioning

confidence: 99%

Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations

Lee¹,

Loh²

2017

Nanotechnology

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Section: Discussionmentioning

confidence: 99%

“…Increased SWNT content, enhanced direct contact, and the possibility of engulfment likely act together to yield the faster inactivation rate observed here for Esterichia Coli. In work on related systems, Szleifer et al,54 and Angelikopoulos and Bock 55-57 have shown, via molecular theory and simulation, the repulsive barrier against aggregation to increase with adsorbed polymer density.These simulation results additionally point to the importance of the size of the PL-PEG micelle hydrophobic core relative to the SWNT diameter. When the former is larger than the latter, micelle-like structures may form around the SWNT, resulting in a high PL-PEG density and enhanced steric repulsion.…”

mentioning

confidence: 99%

Carbon nanotube bundling: influence on layer-by-layer assembly and antimicrobial activity

et al. 2013

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Antimicrobial surfaces are potentially useful for a variety of health care related applications. Single walled carbon nanotubes (SWNT) have shown promise as antimicrobial agents, but important questions persist concerning the effects of tube bundling, a common phenomenon owing to strong hydrophobicity. We investigate 15 here the influence of bundling on the layer-by-layer (LbL) assembly of SWNT with charged polymers, and on the antimicrobial properties of the resultant films. We employ a poly(ethylene glycol) functionalized phospholipid (PL-PEG) to disperse SWNT in aqueous solution, and consider cases where SWNT are dispersed i) as essentially isolated objects and ii) as small bundles. Quartz crystal microgravimetry 20 with dissipation (QCMD) and ellipsometry measurements show the bundled SWNT system to adsorb in an unusually strong fashion -with layers twice (when hydrated) and three times (when dried) as thick as those of isolated SWNT. Molecular dynamics simulation reveals a lower PL-PEG density and degree of solution extension on bundled versus isolated SWNT. These, and especially the lower polymer density 25 results in a lower degree of steric repulsion, which together with stronger van der Waals attraction, may explain the thicker adsorbed layers. Scanning electron micrographs reveal Escherichia coli on films with bundled SWNT to be essentially engulfed by the nanotubes, whereas the bacteria rest upon films with isolated SWNT. While both systems inactivate 90% of bacteria in 24 h, the bundled SWNT system is 30 "fast-acting," reaching this inactivation rate in 1 h. This study demonstrates the significant impact of SWNT bundling on LbL assembly, explores its microscopic origins, and illustrates its use toward bacteria-engulfing, fast-acting, antimicrobial coatings. IntroductionThe impressive physical, mechanical, chemical, electronic, and optical properties of carbon nanotubes (CNT) have established them as a primary research focus since their discovery by Iijima. 1 Research has focussed on developing applications in energy production and storage systems, 2 reinforcements for highperformance composites, 3 sensing materials, 4, 5 drug delivery vehicles, 6, 7 cancer therapeutics, 8,9 and antimicrobial agents. 10,11 Although discovered only recently, the antimicrobial activity of CNT has attracted significant attention. [11][12][13][14][15][16][17] Antimicrobial materials are designed to kill bacteria, and could be used to prevent the infection of medical devices. There are approximately 2 million cases of nosocomial infections in the US annually, and half are associated with implantable devices.18 Thus far, the focus has been primarily on bio-inspired antimicrobial surfaces such as antimicrobial peptides, bacteriolytic enzymes and essential oils, antimicrobial polymers with protonated amine groups, and various antibiotics. [19][20][21] CNT possess certain advantages over other antimicrobial agents: they are highly stable, do not leach over time, are easy to functionalize, and are proving to be compatible with ...

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“…32,34 In particular, Shvartzman-Cohen have used differential scanning calorimetry and spin-probe electron paramagnetic resonance to probe the dynamics of the different Pluronics in the presence of CNTs 23 . More recently, Xin et al 32 they have studied the dispersion of the nanotube by different amphiphilic block copolymers, such as F127, the star-like block copolymer AP432 and L64, using by UV-VIS-NIR measurements and Raman spectroscopy techniques.…”

Section: 31mentioning

confidence: 99%

Coating Mechanisms of Single-Walled Carbon Nanotube by Linear Polyether Surfactants: Insights from Computer Simulations

2014

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ABSTRACT.The non-covalent coating of carbon-based nanomaterials, such as carbon nanotubes, has important applications in nanotechnology and nanomedicine. The molecular modeling of this process can clarify its mechanism and provide a tool for the design of novel materials. In this paper, the coating mechanism of single-walled carbon nanotubes (SWCNT) in aqueous solutions by 1,2 -dimethoxyethane oxide (DME), 1,2 -dimethoxypropane oxide (DMP), polyethylene oxide (PEO), polypropylene oxide (PPO) pentamers, and L64 triblock copolymer chains have been studied using molecular dynamics (MD) simulations. The results suggest a preferential binding to the SWCNT surface of the DMP molecules with respect to DME mainly driven by their difference in hydrophobicy. For the longer pentamers, it depends by the chain conformation. PPO isomers with radius of gyration larger than PEO pentamers bind more tightly than those with more compact conformation. In the case, of the L64 triblock copolymer, the coating of the SWCNT surface produce a shell of PPO blocks with the PEO chains protruding into bulk water as expected from the so-called non-wrapping binding mechanism of SWCNT. In addition, polymer coating, qualitative agreement with experimental evidences on the poor capability of the L64 to disperse SWCNT, do not prevent the formation of CNT aggregates.

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Aggregation and Self-Assembly of Amphiphilic Block Copolymers in Aqueous Dispersions of Carbon Nanotubes

Cited by 71 publications

References 43 publications

Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations

Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations

Carbon nanotube bundling: influence on layer-by-layer assembly and antimicrobial activity

Coating Mechanisms of Single-Walled Carbon Nanotube by Linear Polyether Surfactants: Insights from Computer Simulations

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