Finally, we investigate the electrostatic effect on the synergistic effect, denoted by ∆ el ∆ C F el,W,C (z) involves the solvation of a bare charge and is ill-defined on its own (as was the case for F (2) el,V (z)), and shouldn't be interpreted separately from F (4) el,vw,W,C (z) (see the discussion on Eq. 29). Together, the terms on the right side of Eq. 30 mostly quantify the thermodynamic effects that the polarization of the interfacial water structure (due to introduction of the C 12 E 6 monolayer) has on the water-solvation of the DS -head group at the interface, including orientational effects that direct the DS -head group towards the water (see the discussions on Eqs. 10, 25, and 30).