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Dispersion and Functionalization of Carbon Nanotubes

[size=3][color=Green][b]怎么样更好的分散功能化碳纳米管[/b]
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碳纳米管可能有多方面的应用，其中之一就是分散碳纳米管在溶液中．怎么样分散好纳米管不是一件很容易的是．欢迎大家分享您的经验和技术．一般认为，不同的应用目的可能要用不同的方法．
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[b]Dispersion of Carbon Nanotubes[/b]
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[color=Blue]To disperse carbon nanotubes (CNTs) we recommend the following process.[/color]
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2rHHGM Using the SONICS VCX750 ultrasonic equipment, from Sonics & Materials, Inc. or equivalent, Cheap Tubes Inc. find that adding the dispersant into the solution can accelerate the dispersion effect. The reagent polyvinylpyrrolidone (PVP) is a good dispersion agent. Some people like to use the reagent Sodium dodecyl benzene sulfonate, but we find that the PVP is a better dispersing reagent.%YwffV!SX

ST E jKh+qr The solution is composed of CNTs, PVP, and water, in the proportions of 10 parts CNTs: ~1-2 parts PVP: 2,000 parts water. The required sonication time is ~2 to 8 minutes with an interruption of 10 seconds every 30 seconds. You must prolong the sonication time accordingly, if the power of your ultrasonic equipment is less than that of the SONICS VCX750 unit.qmTOct]b
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It should be noted that our OH and COOH functionalized CNTs can usually be readily dispersed in DI water and a brief sonication step. This dispersion is very stable and the CNTs can remain in solution for weeks or months.  $?'mTZ"t!NSR
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[b]Functionalization[/b]
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}uS J1D!n Pristine nanotubes are unfortunately insoluble in many liquids such as water, polymer resins, and most solvents.  Thus they are difficult to evenly disperse in a liquid matrix such as epoxies and other polymers. This complicates efforts to utilize the nanotubes’ outstanding physical properties in the manufacture of composite materials, as well as in other practical applications which require preparation of uniform mixtures of CNTs with many different organic, inorganic, and polymeric materials.&Qp*V [n _'r
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To make nanotubes more easily dispersible in liquids, it is necessary to physically or chemically attach certain molecules, or functional groups, to their smooth sidewalls without significantly changing the nanotubes’ desirable properties. This process is called functionalization. The production of robust composite materials requires strong covalent chemical bonding between the filler particles and the polymer matrix, rather than the much weaker van der Waals physical bonds which occur if the CNTs are not properly functionalized.
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)KCRj9Tb9ZEh1y0A1\5z+} [b]Functionalization Methods[/b]1A/? A3D J

+ki2y9RM Functionalization methods such as chopping, oxidation, and “wrapping” of the CNTs in certain polymers can create more active bonding sites on the surface of the nanotubes. For biological uses, CNTs can be functionalized by attaching biological molecules, such as lipids, proteins, biotins, etc. to them. Then they can usefully mimic certain biological functions, such as protein adsorption, and bind to DNA and drug molecules. This would enable medially and commercially significant applications such as gene therapy and drug delivery.  In biochemical and chemical applications such as the development of very specific biosensors, molecules such as carboxylic acid (COOH), poly m-aminobenzoic sulfonic acid (PABS), polyimide, and polyvinyl alcohol (PVA) have been used to functionalize CNTs, as have amino acid derivatives, halogens, and compounds.  Some types of functionalized CNTs are soluble in water and other highly polar, aqueous solvents.
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CNT的功能化上，电化学也是一个不错的选择，介绍05年一篇JACS 利用电化学方法在CNT表面功能化上金属纳米材料的工作。
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Electrochemical Templating of Metal Nanoparticles and Nanowires on Single-Walled Carbon Nanotube Networks.F3ad0M\+O*^
  Thomas M. Day,† Patrick R. Unwin,† Neil R. Wilson,‡ and Julie V. Macpherson*,†
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vhA The use of single-walled carbon nanotube (SWNT) networks as templates for the electrodeposition of metal (Ag and Pt) nanostructures is described. Pristine SWNTs, grown on insulating SiO2 surfaces using catalyzed chemical vapor deposition, served as the working electrode. In the simplest case, electrical contact was made by depositing a gold strip on the SWNT substrate (device 1). Deposition of Ag and Pt over extensive periods (30 s) resulted in a high density of particles on the SWNTs, with almost contiguous nanowire formation from the Au/SWNT boundary moving to isolated nanoparticles at further distances from the contact. For direct electrochemical studies of Ag and Pt nucleation, the assembly was coated in a resist layer and a small window opened up to expose only the electrically connected SWNTs to solution4K.o#`:L?oW:H
(device 2). In this case, the electrochemical signature in voltammetric and amperometric studies of metal deposition was due solely to processes at the SWNTs. Coupled with high-resolution microscopy measurements (atomic force microscopy and field emission scanning electron microscopy), this approach provided detail on the nucleation and growth mechanisms of Ag and Pt on SWNTs under electrochemical control. In particular, Ag growth was found to be rapid and progressive with an increasing nanoparticle density with time, whereas Pt deposition was characterized by lower nucleation densities and slower growth rates with a tendency for larger particles to be produced over long times.
gh:r,HV （J. AM. CHEM. SOC. 2005, 127, 10639-10647）

碳纳米管热了这么多年，现在依旧是很具挑战性的前沿领域。。。