π-Electronic Soft Materials Based on Graphitic Nanostructures

Abstract

ABSTRACT:This review focuses on our recent studies on the development of soft materials consisting of graphitic nanostructures. We found that single-walled carbon nanotubes, when suspended in imidazolium ion-based ionic liquids and ground in an agate mortar, form physical gels (bucky gels), where entangled nanotube bundles are exfoliated to give highly dispersed, much finer bundles. The use of polymerizable ionic liquids as the gelling media leads to the formation of highly electroconductive polymer/nanotube composites, which show a dramatic enhancement in mechanical properties. Bucky gels allow the fabrication of the first printable actuator that operates for a long time in air at low applied voltages. We also succeeded in the development of a new family of nanotubular graphite through self-assembly of amphiphilic hexabenzocoronene derivatives. The nanotube consists of a graphitic wall formed from a great number of -stacked hexabenzocoronene units, which provide a charge carrier transport pathway. Suitable chemical modifications of the amphiphile resulted in the formation of nanotubes with various interesting properties. Details of the design, properties, and scope of such -electronic soft nanomaterials are described herein. [doi:10.1295/polymj.PJ2006042] KEY WORDS Nanotube / Nanomaterial / Soft Material / Graphene / Self-Assembly / -Electronic System / Ionic Liquid / A two-dimensional (2D) honeycomb network of sp 2 -hybridized carbon is known as graphene, which stacks in a three-dimensional regular order to form graphite, a traditional carbon material. While the isolation and electronic properties of a single-layered graphene was reported quite recently, 1-3 the 2D carbon layer has drawn considerable attention in relation to carbon nanotubes. Carbon nanotubes are cylindrical carbon nanoclusters with an extremely high aspect ratio, which are formed by rolling-up of a graphene sheet (Figure 1). 4 Since their discovery, 5,6 not only such an interesting structural aspect but also the extraordinary electronic and mechanical properties of carbon nanotubes have fascinated researchers in many fields, thereby leading to remarkable advances in nanoscience and nanotechnology over the last decade.On the other hand, graphene can be regarded as one of the ultimate structural aspects of -conjugated system. Although any methodologies in organic synthesis are currently inaccessible to the infinite 2D carbon layer, organic chemists can design its molecular fragments, i.e., polycyclic aromatic hydrocarbon (PAHs), bearing desired functions. As graphene stacks to form graphite, PAHs possess strong tendency to form one-dimensional columnar structures via -stacking interactions. Since such unidirectionally aligned assemblies of PAHs can provide anisotropic charge carrier and energy transport pathways, PAHs have been considered as promising components for molecular electronic and optoelectronic devices. [7][8][9][10] We were motivated to explore novel materials based on graphitic nanostructures, in particular, focusing on one-dimensi...

Stabilization of a Kinetically Favored Nanostructure: Surface ROMP of Self-Assembled Conductive Nanocoils from a Norbornene-Appended Hexa-peri-hexabenzocoronene

“…Recently, we reported self-assembled nanotubular objects of hexabenzocoronene (HBC) amphiphiles (e.g., 3 ) (Figure ), which consist of helically rolled bilayer tapes composed of bilaterally coupled columns of π-stacked HBC units . In the course of this study we noticed that under certain conditions coiled assemblies occasionally result together with the nanotubes.…”

Comparisons Among Electrical and Rheological Properties of Melt-Mixed Composites Containing Various Carbon Nanostructures

“…Additionally, there has now been interest in graphites or even graphene molecular sheets as fillers that combine high performance with moderate prices (10). Therefore, in addition to the already mentioned conductive fillers, expanded graphite (EG) was incorporated in nanocomposites as a representative of a platelet-like filler with a spectral dimension of d s ≈ 2.…”

Molecular dynamics simulations of self-assembly and nanotube formation by amphiphilic molecules in aqueous solution: a coarse-grain approach

“…In a recent study, Aida and co-workers [36][37][38][39][40][41] demonstrated the formation of one such HARNS by using an amphiphilic hexa-peri-hexabenzocoronene (hbc) that selfassembles in solvent to form a π-electronic, micrometre long, discrete nanotubular objects. The resulting tubes are characterized by an aspect ratio greater than 1000.…”