Volume Expansion and Viscosity Elevation

The polarization of molecules caused by both under-coordination and interelectron-pair repulsion enhances the elasticity and the viscosity of the skin of water, which is generally proportional to the curvature of the interatomic potentials. The high elasticity and the high density of surface dipoles form the essential conditions for the hydrophobicity of a contacting interface [67]. It is now clear why the monolayer film of water is hydrophobic [21]. 

The strengthening of the H-O bond is associated with the interatomic potential well depression, which shifts the from that of an isolated 0 atom is(0) in the form of [68]  

a hybridization of the H-O bond contraction [68, 73, 74], local entrapment and polarization [75, 76], and the segmented H-bond relaxation [77] clarify the anomalous behavior of water molecules with fewer than four neighbors. This exercise also reconciled the anomalies of 0-0 expansion, O Is electron densifi-cation and entrapment, surface electron polarization, high-frequency phonon stiffening, and the ice-ltke and hydrophobic nature of such under-coordinated water molecules. Agreement between numerical calculations and experimental observations validated the following hypothesis and predictions  

Under-coordination-induced H-0 bond contraction and interelectron-pair repulsion-driven 0 H elongation dictate the unusual behavior of water molecules in the nanoscale 0 H-0 networks and in the skin of water. 

The shortening of the H-0 bond raises the density of the core and bonding electrons in the under-coordinated molecules, which in turn polarizes the nonbonding electron lone pairs on oxygen. 

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