Nanolubrication: How do MoS₂-based nanostructures lubricate?

Inorganic MoS₂ nanotubes under high pressure have been investigated at the atomistic scale using Born-Oppenheimer molecular dynamics simulations. We show that the low friction coefficient at high loads is not due to the ball-bearing effect. Instead the nanostructures burst under high loads and form nanoplatelets which attach themselves at the material surfaces of closest contact, effectively leading to local "nanocoating" which results in friction coefficients identical to those of lubricants based on MoS2 platelets. The breakup process always starts from the innermost tube, which opens the possibility to tune the nanomaterials to be effective at well-defined loads.