New developments in the formation of nanotubes from coal

Materials which pack in the form of small rod shapes are of technological interest since they can exhibit considerable strength. In the past decade, we have seen an enormous level of activity in nanostructured materials, fuelled in particular by carbon nanotubes which are closed elongated structures of pure carbon. In our laboratory we have made efforts to synthesise these materials from sources other than graphite and in particular, coal. The work complements a similar program in our laboratory in synthesising fullerenes from coal. Because coal is a molecular solid, and graphite is a lattice solid, there are distinct differences in processing mechanisms between the two materials. Unlike coal, which has weak bonds, graphite, since there are no weak links, has to proceed through a mechanism where single carbon units must be involved, and hence, the products can differ from those derived from coal. The presence of other elements in coal produces a different type of nanotube distribution. Coal also produces other products such as microfilaments and polycyclic hydrocarbons.