Interestingly, the Drude system in vacuum produced a surface potential very similar to the additive systems (Figure ). An additional shoulder peak at ∼1 V was observed, mostly arising from the aromatic ring atoms. Visually, however, the electrostatic potential maps show small differences, mostly associated with locations of positive potential. In contrast, the Drude system in water produced an electrostatic potential clearly shifted towards positive values, leading to a larger distribution of positive potentials across the crystal surface (Figure ). At the same time, the potential was more negative in constricted regions closer to oxygen atoms, reaching values of -2 V, while the strongest potential produced by the Drude system in vacuum was -1.3 V. For comparison, the strongest negative potential produced by the in vacuo and solvated additive systems were -1.4 and -1.5 V, respectively. Overall, such electrostatic effects are likely to impact the water dynamics at the film surface and the desolvation penalty associated with protein binding events to PET crystal films.