| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Carbon nanotube (CNT) can be either metallic or semi-conducting, depending upon its molecular structure. While the metallic CNTs cry more current than ordinary metals, the presently available CNT sample always contain both metallic and semi conducting tubes. Another characteristic of CNT is its excellent mechanical strength. They are stiffer than steal, yet elastic and light. These properties suggest that a self-supporting, conducting, ultra-thin film may be constructed from CNTs. The surface properties of CNTs, however, make this task rather difficult. They show extremely poor wettability toward any solvents or materials. Due to strong van der Waals interactions, they are quite easily aggregated in uncontrollable fashion. In this project, we have employed supramolecular methodology to overcome these problems.
Amines have been known to interact with CNTs. By introducing a template object whose surface has been covered by amines into an unstable CNT dispersion, CNTs coagulate more rapidl
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y to the template than themselves. After adsorption, the template is taken out of the CNT dispersion and the excess dispersion is washed away. Evaporating the solvent off the template surface makes the adsorbed CNT bind tightly to the surface. This adsorption rinse-dry cycle can be repeated using fresh dispersions can grow the CNT film in layer-by-layer.
Firstly, three different kinds of amines was examined for adsorption and MAS-coat glass (high density amines with hydrophilic surface, purchased from MATSUNAMI) was found to give best results. The adsorbed amount and the surface electric resistivity measurements indicated that the 2D percolation takes place at very low surface concentration of CNTs. It is technically difficult to adjust the concentration to the threshold value. Atomic force microscopy was used to measure the area occupied by the CNT network and the average CNT bundle height. They indicate that the adsorption occurs with two different modes. Initially, CNTs interact with the amine to directly adhere onto the amine-covered surface. After the surface coverage reaches a certain value, incoming CNTs interact more strongly with the already adsorbed CNTs. The adsorbed CNTs capture incoming tubes to make the network thicker, rather than covering additional amine surface. Less
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