Polymer modifiers have been used to improve the performances of asphalt binders in pavement engineering. The modifying effect of polymers on asphalt is largely dependent on the morphological characteristics of polymer-modified asphalt. The morphologies of polymer-modified asphalt are composed of a polymer-rich phase, a asphaltene-rich phase, and the interphase between the two phases. Interfacial interactions importantly contribute to the morphology but are commonly overlooked. In this study, carbon nanotubes (CNTs) were selected to improve the interfacial interactions of polymer-modified asphalt. Fluorescence microscopy (FM), scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS), and molecular dynamics (MD) simulation were used to capture the characteristics of the interphase and polymer-rich phase. CNTs-polymer-modified asphalt involves stronger intermolecular forces than those in asphalt-modified by only styrene–butadiene–styrene (SBS) or CNTs. This discrepancy highlights the intensified in...