The organic passivant layer on nanomaterial surfaces has been examined by correlating the phase behavior of the passivant using attenuated total reflection infrared spectroscopy (ATR-IR), coupled with differential scanning calorimetry (DSC). The thermodynamic melting dynamics in the passivant layer supports the description of self-assembled monolayer-like interactions, with an initial constrained chain melting followed by modulation of the surface packing. Correlation of chain length with particle diameter and headgroup functionality suggests that in systems in which the radius of the particle is larger than the passivant layer thickness, chain-chain interactions dominate thermodynamic stabilities, with only a minimal contribution from headgroup stabilization of the passivating layer.