Complex nano-assemblies of polymers and carbonnanotubes

Abstract

Since the discovery of carbon nanotubes in1991 [1], researchers have envisaged potentialapplications such as nanoscale electronic circuits and theconstruction of complex carbon-based nano-machines. Thus, theassembly of basic building blocks of complexnano-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 attachmentto, or modification by carbon nanotubes of structures such aspolymers. This leads to the possibility of assemblingindividual polymer molecules onto carbon nanotubes with the neteffect being the modification of the polymer's electronicproperties and structure in a predictable way. To accomplishthis, clearly, a more detailed understanding of the interactionsbetween conjugated polymers and carbon nanotubes must besought. 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, andscanning tunnelling spectroscopy, we demonstrate that thelow-energy electronic structure of the assembled material isdominated by the one-dimensional nature of the nanotube asreflected in van Hove singularities. Further, we examine themodifications to electronic structure at higher energies usingspectroscopy, which suggests that the polymer's electronicstructure is altered by the introduction of nanotubes.