1 research outputs found
The Mobility of Water Molecules through Hydrated Pores
To achieve a more exact understanding of the water transport
in
natural channels, a series of non-natural structures have been developed.
They have been studied by far-infrared spectroscopy, solid-state nuclear
magnetic resonance, differential scanning calorimetry, thermogravimetric
analysis, and variable-temperature powder X-ray diffraction to examine
the behavior of water at the molecular level. Water in these predominantly
nonpolar pores can be metastable, with filling and emptying occurring
upon changes in solvent conditions. The water contained in these pores
exhibits a dynamics that might be controlled, since it depends on
the structural features of the monomers that form the pore āskeletonā.
We have observed changes in the pore diameter depending on the selected
isomer. This provokes at a given temperature differences in the arrangement
and dynamics of the contained water. The water dynamics increases
with both temperature and pore diameter in a process that is reversible
over a temperature range specific for each structure. Beyond this
particular temperature threshold, the pore water can be irreversibly
evacuated, and at this point a decrease of the dynamics is observed.
The slower dynamics of the remaining water in partially evacuated
pores is probably due to the increased interaction with the inner-pore
surface owing to a concomitant narrowing of the pore. These findings
not only highlight the need for the presence of freely moving water
inside the pore to sustain its permeability by water, but also point
to the decrease in the dynamics of the remaining water in partially
evacuated pores