Nanofatigue of supercrystalline nanocomposites

Supercrystalline nanocomposites (SCNCs) are a new category of hybrid materials consisting of inorganic nanoparticles surface-functionalized with organic ligands and with periodic nanostructures, featuring multi-functionality and able to reach exceptional mechanical properties. Although efforts have been made to explore their mechanical behavior, their response to cyclic loading remains to be unveiled. Here, the fatigue behavior of SCNCs with different degrees of organic crosslinking is investigated via nanoindentation. The nanocomposites’ fatigue life is assessed, and it emerges that SCNCs without crosslinking are more efficient in dissipating energy under cyclic loading and thus feature a longer fatigue life. Chipping is identified as the main fatigue failure mechanism, whereas different mechanisms, intrinsic or extrinsic, dominate in the indentation depth propagation, again depending on crosslinking.