Covalent Surface Chemistry of Single‐Walled Carbon Nanotubes

Banerjee, Sarbajit; Hemraj‐Benny, Tirandai; Wong, Stanislaus S.

doi:10.1002/adma.200401340

Cited by 1,126 publications

(774 citation statements)

References 106 publications

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“…Although vacancy migration in graphite at room temperature is unlikely with migration energies typically reported in the range of a few eV, 56,61 there are indications that covalent binding can take place through vacancies in graphitebased structures. 57, 62 Our results indicate that the geometric effect of vacancies on the surface aggregation of hydrocarbons on graphite is rather small. It is tempting to speculate, however, that covalent bond formation between surfactants and vacancies could be employed to localize surfactant aggregates in selective The angle is calculated with respect to the horizontal direction of Figure 3.…”

Section: Discussionmentioning

confidence: 67%

Surfactant and Hydrocarbon Aggregates on Defective Graphite Surface: Structure and Dynamics

2008

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We have simulated the structure and aggregation kinetics of sodium dodecyl sulfate (SDS) and dodecane (C 12 ) on a graphite surface in the presence of point and line defects. We find that while vacancies do not affect the orientational bias of the molecules, they interfere with aggregate formation. Specifically, they disrupt the formation of extended aggregates. Line defects in the form of surface steps, on the other hand, tend to localize the aggregates in their vicinity and induce specific orientations along the step edges. We demonstrate that this orientational bias can be tuned by manipulating the terrace widths. These results suggest that extended defects could be employed to localize and orient surfactant aggregates on the basal plane of graphite, thus providing a means to create patterned aggregate domains.

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Section: Discussionmentioning

confidence: 67%

Surfactant and Hydrocarbon Aggregates on Defective Graphite Surface: Structure and Dynamics

2008

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“…of CNTs with aryldiazonium salts, first demonstrated by Bahr et al [23] This reaction which occurs at room temperature has been used extensively to attach various organic compounds to CNTs [24,25,26,27]. For the selective placement of nanotubes on metal oxides we combine it with the hydroxamic acid functionality.…”

Section: Figmentioning

confidence: 99%

Field-Effect Transistors Assembled from Functionalized Carbon Nanotubes

Klinke¹,

Hannon²,

Afzali³

et al. 2006

Nano Lett.

136

127

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We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.One-dimensional nanostructures, such as nanowires [1] and carbon nanotubes [2,3] (CNTs) have excellent electrical properties making them attractive for applications in nanotechnology [4,5,6,7]. Semiconducting nanotubes, in particular, are receiving considerable attention due to their very promising performance as channels of field effect transistors (FETs) [8,9,10,11,12]. However, in order for the large-scale integration of CNTs in electronics to take place, many challenges must be overcome. One particularly important problem is selectively positioning CNTs on a substrate. Although considerable progress has been made for nanoclusters [13,14,15] and nanowires [16,17,18] it remains a difficult task for CNTs. Several approaches have been demonstrated based on the chemical patterning of the substrate (typically SiO2) [19,20,21]. In these approaches surfaces are patterned with molecules that either promote or prevent nanotube adhesion. For example, amine-terminated compounds have been shown to enhance nanotube binding while hydrophobic compounds prevent it [22]. Nevertheless, these methods remain unsatisfactory because of the adverse influence of the functionalization on the electrical performance of the devices.Here we propose a new approach that allows to selectively position CNTs based on their functionalization rather than the modification of the substrate. The complete fabrication sequence of chemical functionalization, selective placement, fabrication of multiple devices and defunctionalization is demostrated. High-performance devices can thus be directly assembled. Specifically, we covalently bound molecules to the CNTs that contain the hydroxamic acid functionality (Fig. 1). The functionalized tubes bind strongly to Al2O3 (and other basic metal oxides), but not to SiO2. Upon heating to 600 • C, the functionalization is removed, and the electrical properties of the tube are restored. We exploited the selective bonding to position nanotubes at precise locations on a SiO2 substrate patterned with Al2O3. Using this approach we fabricated FETs with high yield and excellent electrical properties.Our functionalization strategy is based on the reaction * Electronic address: klinke@chemie.uni-hamburg.de; Present address:

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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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Covalent Surface Chemistry of Single‐Walled Carbon Nanotubes

Cited by 1,126 publications

References 106 publications

Surfactant and Hydrocarbon Aggregates on Defective Graphite Surface: Structure and Dynamics

Surfactant and Hydrocarbon Aggregates on Defective Graphite Surface: Structure and Dynamics

Field-Effect Transistors Assembled from Functionalized Carbon Nanotubes

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

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