Molecular Mechanisms\nof Solvation Force for Aqueous\nSystems

Solvation force, stemming from the interfacial liquid\nstructure,\ndominates the short-range interfacial interaction within a few nanometers\nacross broad fields such as battery, lubrication, and colloid. However,\nachieving a quantitative understanding of solvation force for an aqueous\nsystem has remained elusive for decades, with the widely used contact\nvalue theory underestimating solvation force due to inherent assumptions.\nIn this work, inspired by the flow field of liquid when two confining\nsurfaces approach each other, we proposed a parameter-free expression\nfor the solvation force acting on atomically smooth surfaces, quantitatively\nrelated to the energy barrier when liquid molecules are squeezed out\nfrom confinement. The effects of temperature and wetting properties\nof the surface on solvation force curves are found to be different.\nSolvation force measured by three-dimensional atomic force microscopy\n(3D-AFM) validates theoretical prediction on three types of surfaces\nranging from hydrophilic to hydrophobic and reveals that the energy\nbarrier is more intrinsic than density.