Understanding the interfacial interaction characteristics of asphalt nanocomposites reinforced with diamond nanothreads and carbon nanotubes

Diamond nanothreads (DNTs) and carbon nanotubes (CNTs) have emerged as promising reinforcement materials for asphalt. However, the interfacial properties between DNTs/CNTs and asphalt remain poorly understood, hindering the advancement of DNT-/CNT-modified asphalt nanocomposites. In this study, pullout tests were conducted on asphalt nanocomposites reinforced with DNTs, nitrogen-doped diamond nanothreads (NDNTs), and CNTs, to analyze the pullout performance and reinforcing mechanisms across various temperature ranges. The findings reveal that CNT-modified asphalt nanocomposites exhibited superior pullout performance compared to those reinforced with DNTs, primarily due to π-π stacking interactions that facilitated the wrapping of asphalt molecules around CNT surfaces. Among the DNT variants, the DNT2-modified asphalt nanocomposite demonstrated the highest pullout performance, which was attributed to its helical structure that enhanced mechanical interlocking within the asphalt matrix. Notably, NDNTs showed the highest binding energy relative to DNTs and CNTs, stemming from interactions between hydroxyl groups on asphaltene-phenol and nitrogen atoms on NDNTs, leading to the formation of O-H⋯N hydrogen bonds. Density functional theory (DFT) calculations indicated that nitrogen doping modified the electronic structure of NDNTs, resulting in localized negative charges that enhance their overall electronegativity.