Single wall carbon nanotubes distance

The model used in simulations for isolated carbon nanotubes is shown in Figure 1. The tubes consist of n coaxial graphite sheets separated by a distanee A. The inner diameters of the tubes are D which are measured as intemuclear distances. The number of carbon atoms per unit area in the tube wall is pa. All distances relative to the tube are expressed as r, which is the distance from the position of concern to the tube axis. These tubes are then assembled together to form nanotube arrays. For simplicity, only single wall carbon nanotubes and square arrays are considered here. In such a model, parallel single wall carbon nanotubes are placed at comers of squares. A eross-section view of a part of such an array is shown in Figure 2. In addition to the parameters described above for isolated carbon nanotubes, a parameter G is introduced to describe the tube separations in the array G is the intemuclear distance between two adjacent tube walls, see Figure 2. 

Ding, F. (2005). Theoretical study of the stability of defects in single-walled carbon nanotubes as a function of their distance from the nanotube end. Physical Review B, 72, 245409-1-2454 09-7. 

Figure 2 shows a calculation of the distance between nanotubes depending on their volume fraction. For this example, we assumed to have single-wall carbon nanotubes (SWCNT) with a diameter of ca. 1 nm. At a volume fraction of 3%, the distance between two tubes is just two times the diameter (ca. 3.2 nm). If we now assume to have isotactic polystyrene (iPS) as matrix polymer with a chain diameter... 

Depending on the amount of rolled sheets, the CNTs can be divided into two categories those with only one wall, called single wall (SWNT—Single-Wall Nanotubes) or multi-wall (MWNT— Multi-WaU Carbon Nanotnbes). The latter is the result of several coaxial cylinders with a distance similar to the distance between the walls of graphene sheets that make np graphite (0.335 nm [34]).The number of sheets or walls of MWNTs can vary widely, from two (also eaUed DWNT, Double-Wall Carbon Nanotubes) to dozens of walls [35, 36]. MWNTs are usually isolated in synthesis products, while SWNTs are usually produced in the form of bundles of nanotubes [37]. 

MultiwaUed carbon nanotubes (MWNT) consist of a concentric arrangement of single-walled nanotubes with a usually constant distance of layers. There are examples with just two nanotubes fit one into another (sodouble-walled nanotubes, DWNTs) as well as species with many shells (more than 50). The latter measure many nanometers in diameter and may be so hard to distinguish from classical carbon fibers that only electron microscopy can reveal the difference. Common MWNTs, however, possess a smaller number of concentric tubes. The nomenclature of MWNT indicates the intercalation of the inner tubes by the notation (wi,mi) (n2,m2i (n3,m3) ...,starting from the central tube. 

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