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Aligned Carbon Nanotubes
Since 2001, we are developing research studies on synthesis of aligned carbon nanotubes by aerosol-assisted CCVD. This method is based on the catalytic decomposition of liquid carbonaceous sources and involves the simultaneous and continuous feeding of the reactor with the carbonaceous source and the metal catalyst precursor. Nanotubes produced by this process are aligned and contain almost no by-product ; their length can be controlled in a wide range. The aim of our studies is to control this process in order to get aligned nanotubes with physico-chemical characteristics adjusted to various applications. Therefore, we are studying the effects of synthesis conditions on nanotube characteristics. In addition, we are performing studies on the determination and understanding of growth mechanisms of aligned carbon nanotubes. Regarding potential applications of such nanotubes, our motivation is first to demonstrate the ability of this process to be scaled up. The potential applications that we are developing in collaboration with different teams are based both on the alignment and on the length of nanotubes. For instance, we are working on nanoporous membranes useful in various fields (environment, biology,…), or on the adjunction of such nanotubes in different materials in order to make them electrically or thermally conductive.  
Nanotubes aligned perpendicularly to a silicon substrate, such as a carpet.

Nanotubes aligned perpendicularly to a silicon substrate, such as a carpet.
 
Sample obtained after synthesis during 40 s : layer of nanoparticles and nanotub

Sample obtained after synthesis during 40 s : layer of nanoparticles and nanotubes growing on these particles (base-growth mechanism) [M. Pinault, Diamond 2004, Carbon 2005]
 
Multi-layered carpets obtained through a sequential synthesis procedure and show

Multi-layered carpets obtained through a sequential synthesis procedure and showing that any new layer is growing on the substrate under the pre-existing ones by lifting them up. (a) SEM image of a sample synthesised from 5 injection sequences of toluene/ferrocene aerosol ; the duration of the first two sequences are doubled as compared to the last three sequences ; (b) left : SEM image of a sample synthesised from two injection sequence of benzene/ferrocene aerosol, the second sequence contains 13C isotope labels ; right : mapping obtained with nuclear microprobe and showing the diffusion of C through the whole carpet already formed. [M. Pinault, Nano. Lett 2005]