24.7 Summary
491
Theoretical reproduction of the Mpemba paradox profiles—warm water cools
more quickly, evidences the essentiality of the skin high thermal diffusivity.
(2) The nonbonding electron polarization furnishes the surface with excessive
charge and dipoles. The O:H–O bond relaxation and electronic polarization
endowed the aqueous hydration volume and water ice surface with supersolidity that is highly elastic, semi-rigid, electrostatic repulsive, hydrophobic,
slippery, thermally more diffusive and stable with higher melting point T m ,
higher surface stress, mechanical strength, but lower freezing T N and evaporation point T N and mass density. The degree of supersolidity increases with the
surface curvature or with further lowing of the molecular coordination numbers. The supersolidity of nanodroplets, nanobubbles, and molecular clusters is
higher than that of a flat surface, resulting in the super-heating/cooling/cooling
of melting/freezing/evaporating. For instance, a 1.4 nm sized droplet freezes at
205 K [17] instead of the bulk at 258 K [16]. Smaller water supersolid droplet
shows superfluidity, superlubricity, and superhydrophobicity, which enables its
rapid flow when passing through carbon nanotubes or microchannels.
(3) Strikingly, Raman spectroscopy revealed that the skins of 25 °C water and −(15
~ 20) °C ice share H–O bonds of identical length, energy, and vibration frequency
of 3450 cm
−1 . X-ray K edge absorption and Raman scattering unveiled that the
deformed skin H–O bond is thermally much more stable than it is in the bulk.
The supersolidity of the nanodroplet skin hinders vibration energy dissipation
to lengthen the H–O phonon lifetime, according to the ultrafast IR spectroscopy.
(4) The O:H/H–O segmental phonon frequency softening/stiffening offset their
Debye temperatures and disperses outwardly the QS phase boundaries. Hence,
the supersolid skin is neither a liquid nor a solid at the ambient but rather an
extended QS phase having a higher T m (~330 K), lower T N and T V .
(5) Examination of the multifield effect on surface O:H–O bonds and electrons
has cultivated new knowledge and strategies of regulating water evaporation
and desalination, hydrogen generation, and skin supersolidity modulation for
friction and hydrophobicity, etc. Besides, the theory has enabled quantitative
resolutions to anomalies such as ice buoyancy, ice regelation, critical energies
for phase transition, energy exchange by H–O bond relaxation, hydration shell
size and droplet skin thickness determination, etc.
(6) The skin supersolidity is engineerable by O:H–O relaxation and polarization
through programed stimulation. Electrostatic polarization by a parallel electric
field enhances the supersolidity, which enables the water floating bridge to form
and be sustained between two filled cups. An ion forms a semi-rigid supersolid
hydration volume, which separates graphene oxide sheets up to 1.5 nm for the
selective ion rejection. However, a superposition of the applied field and the
ionic field breaks the floating bridge of acid or salt solutions; a mixture of soil
grains and aqueous ions also weakens their fields than either of them alone to
accelerate soil wetting by the salt solutions. Molecular undercoordination and
electrostatic polarization enhances each other to lengthen and weaken the O:H
nonbond whose energy dictates the T N and T V , being beneficial to evaporation
and bio-product cryogenic reservation. Magnetization applies a Lorentz field to
491
Theoretical reproduction of the Mpemba paradox profiles—warm water cools
more quickly, evidences the essentiality of the skin high thermal diffusivity.
(2) The nonbonding electron polarization furnishes the surface with excessive
charge and dipoles. The O:H–O bond relaxation and electronic polarization
endowed the aqueous hydration volume and water ice surface with supersolidity that is highly elastic, semi-rigid, electrostatic repulsive, hydrophobic,
slippery, thermally more diffusive and stable with higher melting point T m ,
higher surface stress, mechanical strength, but lower freezing T N and evaporation point T N and mass density. The degree of supersolidity increases with the
surface curvature or with further lowing of the molecular coordination numbers. The supersolidity of nanodroplets, nanobubbles, and molecular clusters is
higher than that of a flat surface, resulting in the super-heating/cooling/cooling
of melting/freezing/evaporating. For instance, a 1.4 nm sized droplet freezes at
205 K [17] instead of the bulk at 258 K [16]. Smaller water supersolid droplet
shows superfluidity, superlubricity, and superhydrophobicity, which enables its
rapid flow when passing through carbon nanotubes or microchannels.
(3) Strikingly, Raman spectroscopy revealed that the skins of 25 °C water and −(15
~ 20) °C ice share H–O bonds of identical length, energy, and vibration frequency
of 3450 cm
−1 . X-ray K edge absorption and Raman scattering unveiled that the
deformed skin H–O bond is thermally much more stable than it is in the bulk.
The supersolidity of the nanodroplet skin hinders vibration energy dissipation
to lengthen the H–O phonon lifetime, according to the ultrafast IR spectroscopy.
(4) The O:H/H–O segmental phonon frequency softening/stiffening offset their
Debye temperatures and disperses outwardly the QS phase boundaries. Hence,
the supersolid skin is neither a liquid nor a solid at the ambient but rather an
extended QS phase having a higher T m (~330 K), lower T N and T V .
(5) Examination of the multifield effect on surface O:H–O bonds and electrons
has cultivated new knowledge and strategies of regulating water evaporation
and desalination, hydrogen generation, and skin supersolidity modulation for
friction and hydrophobicity, etc. Besides, the theory has enabled quantitative
resolutions to anomalies such as ice buoyancy, ice regelation, critical energies
for phase transition, energy exchange by H–O bond relaxation, hydration shell
size and droplet skin thickness determination, etc.
(6) The skin supersolidity is engineerable by O:H–O relaxation and polarization
through programed stimulation. Electrostatic polarization by a parallel electric
field enhances the supersolidity, which enables the water floating bridge to form
and be sustained between two filled cups. An ion forms a semi-rigid supersolid
hydration volume, which separates graphene oxide sheets up to 1.5 nm for the
selective ion rejection. However, a superposition of the applied field and the
ionic field breaks the floating bridge of acid or salt solutions; a mixture of soil
grains and aqueous ions also weakens their fields than either of them alone to
accelerate soil wetting by the salt solutions. Molecular undercoordination and
electrostatic polarization enhances each other to lengthen and weaken the O:H
nonbond whose energy dictates the T N and T V , being beneficial to evaporation
and bio-product cryogenic reservation. Magnetization applies a Lorentz field to