Figure S1. A photo of water suspension of carbon nano 'test tubes' liberated from the template after Ar ion beam sputtering.

We describe the fabrication of a densely packed ultrathin film of multi-walled carbon nanotubes (MWCNTs) at a liquid-liquid interface. The MWCNTs, which were synthesized using an anodic aluminium oxide (AAO) film as a template, were dispersed in water. Then hexane was added to the dispersion to create the liquid-liquid interface. The MWCNTs were smoothly assembled at the interface to form an ultrathin film when ethanol was added to the MWCNT water dispersion/ hexane solution. The ultrathin film can be transferred onto a solid substrate using the Langmuir-Blodgett deposition technique. With addition of 10 vol% ethanol to the solution, an ultrathin film of MWCNTs with coverage of about 70% was fabricated. The multilayer film was fabricated by repeated deposition of the ultrathin film.

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We report a simple fabrication method for creating a monolayer film of multiwalled carbon nanotubes (MWCNTs). The MWCNTs, which were synthesized using alumina template method, was dispersed in aqueous ethanol solution. Then toluene was added to the dispersion. After sonicating the solution, the MWCNTs form a monolayer at the liquid-liquid interface. The monolayer was transferred onto a solid substrate using simple dipping method. An AFM image showed the formation of a densely packed MWCNT monolayer film.Carbon nanotubes (CNTs) represent an important group of nanomaterials with attractive electronic, chemical, and mechanical properties. Several kinds of electric devices, such as chemical sensors, 1,2 biological sensors, 3-5 field-effect transistors (FET), [6][7][8] and transparent conductive film 9 based on the unique electric properties of the carbon nanotubes have been reported. Implementation of CNTs for these applications requires methods to fabricate carbon-nanotube ultrathin film. Moreover, carbonnanotube ultrathin film is important for understanding its basic electrical and optical properties. Several techniques, such as spraying, 10 self-assembly, 7,11,12 and the Langmuir-Blodgett technique [13][14][15][16][17] have been employed to produce a CNT thin film. Because the Langmuir-Blodgett technique is a suitable method for producing a densely packed film, we and other groups have worked to fabricate a monolayer film of CNT using the LB technique. [13][14][15][16][17] However, the CNT must be modified chemically to prepare the monolayer onto the air-water interface, 14-17 or mixed with surfactants.13 Orikasa et al. synthesized water-dispersible and uniform multiwalled carbon nanotubes (MWCNTs) using template method. 20 The MWCNTs prepared by the template method have uniform length and diameter; they are water-dispersible without additional treatment after synthesis. 20 Here, we report a simple method to fabricate CNT monolayer thin film. We found that the MWCNTs, which were synthesized by the alumina template method 18,19 formed a monolayer at the liquid-liquid interface after sonicating the MWCNT water-oil dispersion. The monolayer is transferable onto solid substrates and the transferred film was observed using atomic force microscopy (AFM).Preparation of MWCNTs by the template method was carried out as described previously. 18,19 An anodic aluminum oxide plate, which has a nanochannel with 10-20 nm diameter and 1 mm length was used as a template. The MWCNTs synthesized using the template method have many oxygen functional groups, such as alcohol, ester, and carbonyl and carboxyl groups, which formed during alkali treatment to dissolve the template. 20 Therefore, the MWCNT synthesized by the template method is easily dispersed in hydrophilic solutions such as ethanol, water, and so on.20 Figure 1 shows an AFM image of the casting of the MWCNT ethanol dispersion onto a silicon substrate. The MWCNTs are uniformly dispersed onto the substrate; each MWCNT is about 1 mm long, which is the same length as the alu...

Water-dispersible and magneto-responsive carbon nano test tubes with a controlled length (1.3 microm) and diameter (35 nm) were synthesized by using the nanochannels of anodic aluminium oxide as a template.