Dynamics of Nafion membrane swelling in H2O/D2O mixtures as studied using FTIR technique

Nikolai F Bunkin; Valeriy A Kozlov; Alexey V Shkirin; Barry W Ninham; Anatoliy A Balashov; Sergey V Gudkov

doi:10.1063/1.5022264

Dynamics of Nafion membrane swelling in H₂O/D₂O mixtures as studied using FTIR technique

J Chem Phys. 2018 Mar 28;148(12):124901. doi: 10.1063/1.5022264.

Authors

Nikolai F Bunkin¹, Valeriy A Kozlov¹, Alexey V Shkirin², Barry W Ninham³, Anatoliy A Balashov⁴, Sergey V Gudkov²

Affiliations

¹ Bauman Moscow State Technical University, Second Baumanskaya Str. 5, Moscow 105005, Russia.
² A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilova Str. 38, Moscow 119991, Russia.
³ The Australian National University, Acton, ACT 2601, Australia.
⁴ Scientific and Technological Center of Unique Instrumentation, Russian Academy of Sciences, Butlerova Str., Moscow 15117342, Russia.

PMID: 29604815
DOI: 10.1063/1.5022264

Abstract

Experiments with 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 studied, depending on the deuterium content in water in the spectral range 1.8-2.15 μm. The experiments were carried out using two protocols: in the first protocol we studied the dynamics of Nafion swelling in H₂O + D₂O mixtures for the deuterium concentrations 3 < C < 10⁴ ppm, and in 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 using 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), were studied. The experimentally estimated diffusion coefficient for this process is ≈6·10^-11 cm²/s.