ABSTRACT

Helix-shaped nanostructures are described in the available literature as nanosprings, nanocoils, and nanospirals. These structures are generally reviewed among other related nanoforms (such as nanowires, nanorods, or nanoneedles).1,2 A computational quantum chemistry design of nanospirals was also reported.3 As the majority of other related nanostructures, helix nanostructures are represented mainly by inorganic compounds, in particular carbon nanotubes4 (CNTs) and other carbon nanoforms. Thus, a constant-force nanospring might be formed from a con£guration of concentric CNTs (Figure 10.1), where the van der Waals force provides the extension-independent restoring force.5 A telescoped nanotube with only one active (sliding) surface pair was expected to act as a constant-force spring. A fully telescoped MWNT (Figure 10.2) originally had nine walls, with an outer diameter of 8 nm and an inner diameter of 1.3 nm.