Unconventional nanotubes self-assembled in alumina channels: morphology and surface potential of isolated nanostructures at surfaces

Abstract

Synthetic nanographenes have been self-assembled from solution on the surface of nanometric channels of an alumina membrane template. By controlling the interplay between intermolecular and interfacial interactions, the molecules have been adsorbed either 'face-on' or 'edge-on' on the pore's surfaces, leading to the formation of columnar stacks in the latter case. Upon thermal treatment at high temperature, the molecular cross-linking of the columns has been triggered, transforming the delicate supramolecular arrangement into robust carbon nanotubes, with the graphitic planes at predetermined orientations with respect to the tube axis. Scanning force microscopy characterization of single nanotubes deposited from suspensions on mica showed that the nanotubes can selfassemble on flat surfaces adopting preferential alignments which reflect the threefold symmetry of the mica substrate. Kelvin probe force microscopy studies revealed that the nanotubes possess a surface potential much smaller than the work function of both graphite and conventional vacuum-processed nanotubes, providing evidence for their more confined electronic structure.

Supramolecular Organization of Polymeric Materials in Nanoporous Hard Templates

“…Pentacene nanotubes prepared by melt infiltration and slow cooling to room temperature [131] exhibited no long-range order. Also, HBCs that were designed in such a way that they anchor face-on on smooth sub-strates did not yield nanotubes with uniformly oriented graphene layers when deposited into AAO templates [132]. Thus, it seems that the suppression of face-on anchoring leading to homeotropic orientation of the columns, for example by using molecular building blocks that tend to intercolumnar π-π stacking, results in the formation of highly ordered planar mesophases.…”

Mesoscopic Structure Formation in the Walls of Nanotubes Confined to Nanoporous Hard Templates

“…Pentacene nanotubes prepared by melt infiltration and slow cooling to room temperature [69] exhibited no long-range order. Also, HBCs that were designed in such a way that they anchor face-on on smooth substrates did not yield nanotubes with uniformly oriented graphene layers when deposited into AAO templates [70]. Thus, it seems that the suppression of face-on anchoring leading to homeotropic orientation of the columns, for example by using molecular building blocks that tend to intercolumnar π-π stracking, results in the formation of highly ordered planar mesophases.…”