Complex nano-assemblies of polymers and carbon nanotubes

Since the discovery of carbon nanotubes in 1991 [1], researchers have envisaged potential applications such as nanoscale electronic circuits and the construction of complex carbon-based nano-machines. Thus, the assembly of basic building blocks of complex nano-architectures, such as conjugated polymers and nanotubes, has been a driving goal of much of the nano-science community. A first step towards realizing this goal may be the attachment to, or modification by carbon nanotubes of structures such as polymers. This leads to the possibility of assembling individual polymer molecules onto carbon nanotubes with the net effect being the modification of the polymer's electronic properties and structure in a predictable way. To accomplish this, clearly, a more detailed understanding of the interactions between conjugated polymers and carbon nanotubes must be sought. In this paper, we describe the assembly of the polymer, poly(m-phenylenevinylene-co-2,5-dioctoxy-p-phenylenevinylene) (PmPV), into a coating around single-walled carbon nanotubes. Using scanning tunnelling microscopy, and scanning tunnelling spectroscopy, we demonstrate that the low-energy electronic structure of the assembled material is dominated by the one-dimensional nature of the nanotube as reflected in van Hove singularities. Further, we examine the modifications to electronic structure at higher energies using spectroscopy, which suggests that the polymer's electronic structure is altered by the introduction of nanotubes. (Some figures in this article are in colour only in the electronic version).