Surface modifications for the effective dispersion of carbon nanotubes in solvents and polymers

Kim, Sang Won; Kim, Tae-Hoon; Kim, Yern Seung; Choi, Hong Soo; Lim, Hyeong Jun; Yang, Seung Jae; Park, Chong Rae

doi:10.1016/j.carbon.2011.08.011

Cited by 624 publications

(334 citation statements)

References 285 publications

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“…Such CNT dispersion in aqueous environment can be achieved by covalent hydrophilic or non-covalent amphiphilic functionalization, see, e.g., Refs. [4][5][6] Non-covalent functionalization, e.g., polymers, surfactants, and lipids, is often preferred as it maintains the individual CNT structure, and properties intact. In general, in non-covalent functionalization of CNTs, the hydrophobic interactions between the solvating molecule and the graphitic surface induce adsorption, while the hydrophilic sections provide effective repulsion against rebundling which stabilizes the aqueous dispersion.…”

Section: Introductionmentioning

confidence: 99%

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

2015

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Control of aqueous dispersion is central in the processing and usage of nanoscale hydrophobic objects. However, selecting dispersive agents based on the size and form of the hydrophobic object and the role of coating morphology in dispersion efficiency remain important open questions. Here, the effect of the substrate and the dispersing molecule curvature, as well as, the influence of dispersant concentration on the adsorption morphology are examined by molecular simulations of graphene and carbon nanotube (CNT) substrates with phospholipids of varying curvature as the dispersing agents. Lipid spontaneous curvature is increased from close to zero (effectively cylindrical lipid) to highly positive (effectively conical lipid) by studying double tailed dipalmitoylphosphadidylcholine (DPPC) and single tailed lysophosphadidylcholine (LPC) which differ in the number of acyl chains but have identical head group.We find that lipids are good dispersion agents for both planar and curved nanoparticles and induce a dispersive barrier non-size selectively. Differences in dispersion efficiency arise from lipid head group density and their extension from the hydrophobic substrate in the adsorption morphology. We map the packing morphology contributing factors and report that the aggregate morphologies depend on the competition of interactions rising from 1) hydrophobicity driven maximization of lipid-substrate contacts and lipid self-adhesion, 2) tail bending energy cost, 3) preferential alignment along the graphitic substrate principal axes, and 4) lipid head group preferential packing.Curved substrates adjust the morphology by changing the balance between the interaction strengths. Jointly, the findings show substrate curvature and dimensions are a way to tune lipid adsorption to desired, self-assembling patterns. Besides engineering dispersion efficiency, the findings could bear significance in designing materials with defined molecular scale, molecular coatings for orientation specific CNT assembly or lipid-based molecular masks and patterning on graphene.2

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Section: Introductionmentioning

confidence: 99%

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

2015

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“…Although a common phenomenon, the influence of bundling on both the LbL assembly and the properties of the assembled film is not well understood. 24 In this study, we disperse single walled CNT (SWNT) with an amphiphilic polymer, poly(ethylene glycol) functionalized phospholipid (PL-PEG), such that SWNT exist i) as essentially isolated objects, and ii) as small bundles. We then investigate the LbL assembly of isolated and bundled SWNT with charged polymers, and the antimicrobial properties of the resultant films.…”

Section: Introductionmentioning

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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“…10 Analytical applications of CNDs have been also reported for the detection of metal ions 11 and phosphate, 12 utilizing CND-metal ion affinity based on the carboxylic functionality of the CNDs surface. In recent years, aryl radical reactions were applied to modify nanocarbons, such as carbon nanotubes 13 and graphene, 14 mainly for the effective dispersion in solvents by introducing benzene-sulfonic groups.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescent Detection of Nitrite with Carbon Nanodots Prepared by Microwave-assisted Synthesis

et al. 2015

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A photoluminescent detection method for nitrite with high selectivity and sensitivity using carbon nanodots (CNDs) is demonstrated. The selectivity of nitrite is accomplished by a highly specific diazotization reaction between nitrite and p-phenylenediamine (p-PDA). In the presence of nitrite, p-PDA easily reacts to form the diazonium cation in the acidic aqueous solution. By alkalization of the reaction mixture, diazonium cation of p-PDA was converted to an aryl radical to form aggregated CNDs, which causes the change in the photoluminescent intensity of CNDs. In the present method, nitrite can be selectively detected down to 1 μM over several anions, such as nitrate, perchlorate, sulfate, fluoride, chloride, and bromide at mM levels.

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Surface modifications for the effective dispersion of carbon nanotubes in solvents and polymers

Cited by 624 publications

References 285 publications

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

Controlling Carbon-Nanotube—Phospholipid Solubility by Curvature-Dependent Self-Assembly

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

Photoluminescent Detection of Nitrite with Carbon Nanodots Prepared by Microwave-assisted Synthesis

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