Skin Supersolidity of Water and Ice

The skins of water ice share the same nature of supersolidity, which is elastic, hydrophobic, polarized, highly thermal stable, slippery. 

H—0 bond contraction and the associated bonding electron entrapment and the dual processes of polarization create the supersolidity. 

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Table 39.1 Skin supersolidity (rox, <4. P) of water and ice derived from the measurements (indicated with refs) and methods described in [29, 30]...

Figure 38.2 shows the solution consistency to the measured molecular size dn, molecular separation dL (or doo), mass density p, and structural order of (1) compressed ice [30], (2) cooling water and ice [28, 29], and (3) water surface and molecular dimer [3, 6]. Currently derived dn of 1.0004 A at unity density is within the measured values ranging from 0.970 to 1.001 A [14]. The doo values greater than the ideal value of 2.6950 A at p = 1 (g cm ) correspond to the supersolid phase (low density, LDP) that exists indeed [15, 21, 22] but only in the skins of water ice composed of molecules with fewer than four neighbors (Fig. 38.2b) [17]. 

Skin supersolidity slipperizes ice. The H-O contraction, core electron entrapment and dual polarization yield the high-elasticity, self-lubrication, and low-friction of ice and the hydrophobicity of water surface as well, of which the mechanism is the same to that of metal nitride [45, 46] and oxide [47] surfaces. Nanoindentation measurements revealed that the elastic recovery coefficient of TiCrN, GaAlN, and a-Al203 surfaces could reach 100 % under a critical indentation load of friction (<1.0 mN) at which the lone pair breaks with a friction coefficient being the same order to ice (0.1) [42], see Fig. 39.2. Albeit the pressure and the nature of loading pin materials, both show the comparatively low friction coefficients. The involvement of lone pairs makes the nitride and oxide surfaces more elastic and slippery under the critical load. This understanding supplements mechanism for the slippery of ice surface and the hydrophobicity of ultrathin water films as well. 

These discoveries further evidence for the elastic, solid-Uke, polarized, and hydrophobic attributes of the skin of ice and water or the topological defects. The fewer the molecular neighbors is, the smaller the water molecule size (i n). the greater the molecular separation (doo). and the greater extents of the supersolidity attributes will be. 

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