Molecular dynamics investigations on the interfacial energy and adhesive strength between C60-filled carbon nanotubes and metallic surface

The mechanical and adhesive properties of C60@(10,10) carbon nanopeapods (CNPs) adhering to gold surfaces are investigated by atomistic simulations. The effects of C60 fill density, tube length, surrounding temperature, and peeling velocity on the adhesion behavior are studied. Results show that the interfacial binding energy of CNPs (which depends on the C60 fill density and temperature) is 2.0∼4.4% higher than that of (10,10) single-walled CNTs and 3.4∼4.7% lower than that of (5,5)@(10,10) double-walled CNTs (DWCNTs). Despite their lower interfacial binding energy, CNPs have a higher adhesive strength than that of DWCNTs (1.53 nN vs. 1.4 nN). Distinct from the inner tubes of DWCNTs, which have continuum mechanical properties, the discrete C60 molecules that fill CNPs exhibit unique composite mechanical properties, with high flexibility and bend-buckling resistance. The bend-buckling forces for CNPs filled with a low/medium fill density of C60 are approximately constant. When the fill density is 1 C60 molecule per nanometer length, the bend-buckling force dramatically increases.