Nanoscale assembly: C₇₂₀ to 3D fullerene networks via interfacial cross-linking and property impacts

In this study, a three-dimensional fullerene network was successfully fabricated using fullerene C₇₂₀ as the basic unit. Covalent bonds were formed at the interfaces by introducing a series of different vacancy concentrations. Molecular dynamics simulations were employed to deeply explore the structural evolution during vacancy-induced interfacial cross-linking and its impacts on the mechanical behavior and thermal transport properties of the material. It was found that after high-temperature thermal annealing, the interface of the fullerene network was connected by sp, sp², and sp³ C-C bonds, with the interfacial connection strength mainly determined by sp and sp² C-C bonds. The structures and properties of the fullerene network vary at different defect concentrations. For example, at a 5 % defect concentration, it is in a disordered state, showing layer-by-layer failure and large strain during tension; while at 10 %–20 % defect concentrations, it maintains the initial simple cubic stacking and undergoes brittle failure during tension. During compression, the structural changes lead to a first -increase-then-decrease in the load-bearing capacity. In terms of thermal transport performance, the increase in the number of interface connections significantly enhances heat transfer and plays a dominant role.