The research of time dependence polymeric membrane swelling in water with various deuterium content

Abstract

Experiments on the Fourier transform spectrometry of Nafion, a water-swollen polymeric membrane, are described. The transmittance spectra of liquid samples and Nafion, soaked in these samples, were examined, depending on the deuterium content in water within the spectral range 1.8-2.15 μm. The experiments were carried out according to two protocols: with the first protocol we studied the dynamics of Nafion swelling in H2O + D2O mixtures for the deuterium concentrations 3 < C < 104 ppm, and with the second protocol we studied the dynamics of swelling in pure heavy water (C = 106 ppm). For liquid mixtures in the concentration range 3 < C < 104 ppm, the transmittance spectra are the same, but for Nafion soaked in these fluids, the corresponding spectra are different. It is shown that, in the range of deuterium contents C = 90-500 ppm, the behavior of transmittance of the polymer membrane is non-monotonic. In experiments with the second protocol, the dynamics of diffusion replacement of residual water, which is always present in the bulk of the polymer membrane inside closed cavities (i.e., without access to atmospheric air), was studied.