In addition to depending on material properties such as the bulk modulus, speed of sound, thermal conductivity, etc, the frictional properties of an interface also depend on microscopic interactions that are uniquely accessible to computer simulation. These include the chemical reactivity or inertness of the interface, cohesive and solvation forces, as well as electrostatic effects. Carbon Nanotubes Discovered only in the previous decade, carbon nanotubes have remarkable properties which have caused them to be widely studied. Smalley and coworkers, for example, have suggested that nanotubes would be ideal for use as tips on scanning probe microscopy instrumentation. Typically, instruments such as the atomic force microscope use a sharp metal tip to probe the properties of an interface.
Nanotubes offer considerable advantages over cut, etched, or otherwise sharpened metal tips.
The primary advantage is that single-walled nanotubes have a tip radius which is orders of magnitude smaller than macroscopically machined metal tips, and thus are perfect for exploring the atomic structure of interfaces. Also of interest are the chemical inertness and remarkable material properties of carbon nanotubes, which allow them to be used under conditions which would damage a metal tip. In order to use nanotubes effectively in this type of instrumentation, however, their mechanical properties must be understood. Specifically, their response to both axial and lateral loads must be evaluated. While experimental techniques and theoretical models have been able to shed some light on these questions, computational studies have also proved valuable.