Liquid crystal engineering of carbon nanofibers and nanotubes

Chan, Christopher D.; Crawford, Gregory P.; Gao, Yuan; Hurt, Robert H.; Jian, Kengqing; Li, Hao; Sheldon, Brian W.; Sousa, Matthew E.; Yang, Nancy Y. C.

doi:10.1016/j.carbon.2005.04.033

Cited by 60 publications

(52 citation statements)

References 33 publications

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“…During solidification and carbonization by further heating, the orientation is preserved to form finally well-developed platelet structure carbon nanofilaments. This is essentially similar to the carbon nanofilaments formed from mesophase pitch in porous alumina template [18,20]. generates corrosive hydrogen chloride gas, and it is likely that aluminum oxide is etched by such an aggressive gas.…”

Section: Formation Of Platelet Carbon Nanofilamentsmentioning

confidence: 72%

“…The template materials play an important role on orientation of graphene layers in carbon nanofilaments. The use of metallic aluminum template with square tunnel pits of 1 μm square as a template and PVC precursor results in the formation of carbon filaments with a concentric structure [19], and similar structure has been obtained from a carbon-lined porous alumina template and mesophase pitch precursor [20].…”

Section: Introductionmentioning

confidence: 85%

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Structure of the carbon nanofilaments formed by liquid phase carbonization in porous anodic alumina template

Habazaki

Kiriu

Hayashi

et al. 2007

Materials Chemistry and Physics

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Platelet structure carbon nanofilaments of ~30 nm in diameter have been prepared by heating a mixture of porous anodic alumina template and poly(vinyl)chloride powders in an argon atmosphere, and the change in their structure and morphology with heat treatment temperature, ranging from 600 to 2800°C, has been examined using XRD, scanning electron microscopy, transmission electron microscopy and nitrogen gas adsorption measurements.The diameter of the carbon nanofilaments formed does not change with heat treatment temperature, being in agreement with the pore diameter of the template, while their length is reduced with the temperature. The platelet-type orientation of graphene layers is evident even at 600 o C with the layer structure further developing with increasing heat treatment temperature. The carbon nanofilaments formed at lower temperatures have micropores, while those formed at higher temperatures do not have porosity. Highly graphitized carbon nanofilaments have been obtained after heat treatment at 2800°C, with another characteristic structural feature being presence of loops at the edge of graphene layers formed at 2800°C.

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Section: Formation Of Platelet Carbon Nanofilamentsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 85%

Structure of the carbon nanofilaments formed by liquid phase carbonization in porous anodic alumina template

Habazaki

Kiriu

Hayashi

et al. 2007

Materials Chemistry and Physics

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“…Recent results have demonstrated that polyaromatic LC precursors can be used to fabricate various nanocarbons with high concentrations of edge-plane surfaces. [23][24][25] This structure arises naturally in discotic supramolecular chemistry, where maximization of internal p-p interactions drives peripheral hydrogen or hetereoatom groups toward phase boundaries in most cases. [26] Prior to dehydrogenative carbonization, these edge-plane surfaces form spontaneously as the lower-free-energy crystal facet.…”

mentioning

confidence: 99%

“…[26] A disadvantage of previous LC-derived nanocarbons is the need for a sacrificial nanostructured template to direct the alignment of the discotic molecules. [23][24][25]27] The phenomenon of directed LC surface anchoring does not, however, require solid surfaces, but is generalizable to other types of phase boundaries. The solution/gas interface at the edge of microdroplets offers a potential template-free method for directing discotic assembly in carbon nanoparticles.…”

mentioning

confidence: 99%

“…The solution/gas interface at the edge of microdroplets offers a potential template-free method for directing discotic assembly in carbon nanoparticles. Our most recent work [24,28] has identified a water-soluble lyotropic LC that undergoes this assembly and covalent capture scheme and is an effective precursor for carbons. Indanthrone disulfonate is a lyotropic LC, which exhibits order/disorder transitions as a function of concentration.…”

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confidence: 99%

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Biocompatible, Hydrophilic, Supramolecular Carbon Nanoparticles for Cell Delivery

Yan¹,

Lau²,

Weissman³

et al. 2006

Advanced Materials

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Carbon nanomaterials have received recent attention as biomolecular carriers, [1][2][3][4][5] capable of transporting covalently bonded drugs or molecular probes across cell membranes.The poor cellular penetration of many small molecules and proteins can be overcome by conjugation to a nanomaterial carrier, whose size, shape, and surface chemistry can be engineered for optimal cellular uptake. The seminal work cited above [1,2] focused on carbon nanotubes but we believe that spherical carbon nanoparticles may be a superior platform. Their simple geometry and freedom from entanglement ensures a consistent effective size for cell uptake and a uniform surface chemistry. Indeed, particle size and shape are key variables determining the rates and mechanisms of cellular uptake. Endocytotic uptake has recently been proposed to occur at an optimum diameter of about 50 nm with significantly lower rates for both larger and smaller particles.[6] Larger particles are typically taken up by phagocytosis, a separate cellular mechanism driven by the actin myosin cortex in professional phagocytic cells such as macrophages and amoeba. [6] In targeted therapies, uptake by the mononuclear phagocyte system can be minimized by using hydrophilic nanoparticles smaller than 100 nm, [7,8] allowing the carriers to reach the target tissue. We see great potential to develop carbon-based biomolecular carrier platforms in which nanoparticle size and surface chemistry are tuned to i) preferentially target nonphagocytic cells, and ii) control biodistribution and cellular uptake to localize nanoparticle conjugates at diseased sites.[8]Carbon nanoparticles are potentially biocompatible, nonimmunogenic [9] and offer a range of options for carrying active agents, which include surface adsorption or deposition, pore filling, incorporation in the carbon matrix, and surface covalent coupling. A variety of carbon nanoparticles have been synthesized, [10][11][12][13][14][15] motivated almost entirely by non-biological applications. An exception is Rudge et al., [16] who developed iron-carbon composite microparticles (0.5-5 lm) for targeted chemotherapy delivered through intra-arterial injection. Carbon nanoparticles are readily available in the form of carbon blacks, commodity materials with primary particle sizes ranging from 12 to 100 nm. The primary nanoparticles in carbon blacks are linked into fused fractal aggregates, however, which exhibit much larger and uncontrolled effective particle sizes. In addition, carbon-black particles have concentric (onionlike) graphene layer symmetry, and, in common with most other high-temperature nanocarbon forms, have hydrophobic, low-polarity, low-reactivity surfaces that present challenges for dispersion and functionalization.We are specifically interested in developing carbon nanoparticles as platforms for delivery to mesothelial cells. For this application the materials development should focus on the following goals: i) explicit control of particle composition and size across the endocytic/phagocytic size rang...

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Covalent Capture of Self‐Assembled Soft Materials

Gong

2012

Supramolecular Chemistry

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This chapter describes the covalent capture of soft materials with examples from covalently captured liquid crystals as well as gels of small molecules and polymers. The interplay of self‐assembly and the incorporation of various covalent bonds, including irreversible and covalent reversible bonds, are discussed. The development of basic, tunable association units allowing the systematic control of molecular assembly and covalent capture is speculated.

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Liquid crystal engineering of carbon nanofibers and nanotubes

Cited by 60 publications

References 33 publications

Structure of the carbon nanofilaments formed by liquid phase carbonization in porous anodic alumina template

Structure of the carbon nanofilaments formed by liquid phase carbonization in porous anodic alumina template

Biocompatible, Hydrophilic, Supramolecular Carbon Nanoparticles for Cell Delivery

Covalent Capture of Self‐Assembled Soft Materials

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