van der Waals Layer-by-Layer Construction of a Carbon Nanotube 2D Network

Abstract

The acid-treated single-walled carbon nanotubes (SWCNTs) dispersed in water are only kinetically stable with electrostatic double layer repulsions just balancing against van der Waals (VDW) attractions. Introducing any external factor to disturb this balance causes immediate coagulation of SWCNTs. Here, an amine-covered flat substrate was immersed in the dispersion to initiate adsorption of SWCNTs onto the substrate surface. By repeating an adsorption-rinse-dry cycle, it was possible to deposit SWCNT bundles in a layer-by-layer fashion and to develop a 2D network consisting only of SWCNTs that are held by VDW interaction. We show that (1) adsorbed solution-grown aggregates are not relevant for the network connectivity, (2) 2D percolation takes place at very low surface coverage, (3) the electrical resistivity follows a power law against the layering cycles, (4) not only the adsorbed amount but also the added amount per layering cycle increases linearly with the SWCNT concentration, and (5) after the adsorption is initiated by amines, VDW attraction takes over for subsequent adsorption, with the consequence that the newly adsorbed SWCNTs are used to thicken each arm of the network rather than to cover more free surfaces.

Non-isothermal crystallization kinetics of syndiotactic polystyrene polystyrene functionalized SWNTs nanocomposites

“…such as deposition using layer-by-layer assembly have also been applied [21][22][23]. Although the techniques are inherently different, all of them try to address issues that directly affect the composite properties, such as deagglomeration of bundles and ropes, CNTs dispersion, and interfacial bonding.…”

Incorporation of Single-Walled Carbon Nanotubes into Functional Sensor Applications

“…This greatly increases reproducibility in device manufacture, facilitating the mass production of SWNT-based devices. [94][95][96] Research that has been done on this topic indicates a strong correlation between the experimental data and the predicted results made using percolation theory; this theory maintains that the density of SWNTs defines the conductivity of the network by way of the following expression: 98 Where is the conductivity in three dimensions, or the sheet conductance "G" in two dimensions, N is the density of nanotubes and N c is the critical density defining the percolation threshold. Therefore, this equation describes the relationship between the actual density of SWNTs on the surface (N and the critical density (N c , below which conductivity does not occur.…”

“…Percolation theory describes how a random network of SWNTs will behave as a semiconducting film in the limit between the percolation thresholds for the semiconducting and metallic SWNTs. [94][95][96] In this range, semiconducting pathways dominate the film and metallic pathways are not favored until the percolation threshold for the metallic SWNTs is exceeded (Fig. 5).…”

Assembly of Polyelectrolytes on CNTs by Van der Waals Interactions and Fabrication of LBL Polyelectrolyte/CNT Composites

“…Sato and Sano showed an interesting example sequential assembly of CNTs in a layered way employing Van der Waals interactions between the deposited CNTs and the next assembling CNTs layer. [24] However, this is the first time that carbon nanotubes have been included both as positive and negative component in a LBL assembly. An important feature of the fabricated films is that they present a porous structure.…”