A Fourier ir spectroscopy study of the effects of unsteadiness on the process of swelling of polymeric membranes

The process of swelling of a Nafion polymer membrane in water poured into a cell with a charac- teristic size of the same order of magnitude as the membrane thickness itself is experimentally studied by Fourier transform infrared spectroscopy. These studies are of interest because of the fact that the polymer fibers are effectively unwound to a volume of water when Nafion swelling occurs in a cell with the size that is much larger than the membrane thickness. However, this process has not been studied for the case when the area that can be occupied by the polymer fibers unwound to a volume of the liquid is limited by the cell size. It is shown that the temporal dynamics of the transition of the polymer from the hydrophobic state to the hydrophilic one in this case has a number of specific features that depend on the cell size, as well as on the isotopic composition, the content of ions, and water pretreatment.