The key challenge is to strategically translate the segmental dynamics into the quantitative ligand-ligand interaction strength. In this work, we propose the novel concept of "dynamic volume" which depicts the accessible space of a chain segment under the confinement of neighboring molecules. This dynamic volume can be derived from NMR-measured motional amplitude combined with a simple geometric consideration of the surface ligand layer. Mathematically, the dynamic volume is inversely proportional to the intermolecular interaction, i.e., the cohesive energy, between segments. We construct an extensible numerical model to calculate the total ligand-ligand interaction energy on NCs with pure or mixed aliphatic ligands. This model not only translates NMR measurables into interaction energies, but also accommodates semi-empirical predictions without relying on NMR measurements. We show that the interaction energy fundamentally determines the thermodynamic processes of solution dispersion and melting transitions of NCs. Our study quantitatively elucidates both the molecular picture and the collective impact of ligand-ligand interactions on NCs. The dynamic volume concept based on the advanced analyses of segmental motion offers a precision gauge to assess weak non-covalent interactions .