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

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 HO + DO mixtures for the deuterium concentrations 3 < C < 10 ppm, and in the second protocol we studied the dynamics of swelling in pure heavy water (C = 10 ppm). For liquid mixtures in the concentration range 3 < C < 10 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 cm/s.

Influence of Fluoropolymer Film Modified With Nanoscale Photoluminophor on Growth and Development of Plants

“…The developed technology of low-temperature incorporation of QD into the polymer also makes it possible to work in the future with various types of nanoparticles. A possible unsolved problem is the vapor permeability of fluoropolymers, especially in the surface layer [27], although this index of fluoropolymers is often much lower compared to other classes of polymers [28].…”

Formation of Water-Free Cavity in the Process of Nafion Swelling in a Cell of Limited Volume; Effect of Polymer Fibers Unwinding

“…It can be seen that this spectrum differs significantly from the DDW spectra. According to Reference [28], the transmission spectra of water in the range 1.8 < λ < 2.2 μm are the same for the samples with the deuterium content 1−10 4 ppm, i.e., the detected effect cannot be associated with various absorptivity of ordinary water and DDW. We associate the difference in these spectra with the absence of the empty cavity in DDW.…”

“…In this subsection, we shortly describe an experimental protocol of our FTIR experiments (for more detail, see Reference [28]). In these experiments, the transmittance spectrum K = I/I 0 was measured, where I 0 is the intensity of the radiation, falling on the cell with liquid and Nafion plate, and I is the transmitted radiation.…”

Исследование Набухания Полимерных Мембран В Кювете Ограниченного Размера С Помощью Фурье Ик-Спектрометрии

“…Область, из которой эффективно выталкиваются коллоидные микросферы, получила название «исключенной зоны». Известно, (см., н-р, [7] и приведенные в этой работе ссылки), что твердотельная подложка может изменять свойства прилегающей к ней воды только в пределах 1-2 монослоев, т.е. в масштабах нескольких нанометров.…”

“…в масштабах нескольких нанометров. Как и в описанных ранее экспериментах [8,9], коэффициент пропускания исследован в диапазоне 1.8-2.2 мкм (по поводу выбора этого диапазона см. детальный комментарий в работе [7]).…”