Diffusion in Sulfonated Co-Polynaphthoyleneimide Proton Exchange Membranes with Different Ratios of Hydrophylic to Hydrophobic Groups Studied Using SFG NMR

Zavorotnaya, U.M.; Privalov, A.F.; Kresse, B.; Vogel, M.; Ponomarev, I.I.; Volkova, Y.A.; Sinitsyn, V.V.

Авторы: Zavorotnaya Ulyana M., Privalov Alexei F., Kresse Benjamin, Vogel Michael, Ponomarev Igor I., Volkova Yulia A., Sinitsyn Vitaly V.
Журнал: Macromolecules
Год издания: 2022
Издательство: American Chemical Society
Местоположение издательства: United States
DOI: 10.1021/acs.macromol.2c01486
Аннотация: We use static field gradient (SFG) NMR to determine the self-diffusion coefficients of protons in fluorine-free sulfonated co-polynaphthoyleneimide (co-PNIS) proton exchange membranes with different ratios of hydrophilic to hydrophobic groups. The investigations were carried out in the temperature range from 193 to 355 K. Because there are protons not only in water but also in the polymer framework, 1H NMR diffusion studies of these membranes may suffer from cross-relaxation effects between the different types of protons. To overcome this problem, different methods for measuring proton diffusion coefficients are compared and a suitable strategy for analysis is proposed. It is found that the proton diffusion is practically isotropic and shows two activation regimes, separated by a crossover near 260 K. The activation energy above the crossover is 0.19 eV, which is close to that of Nafion 212. Below the crossover, all co-PNIS membranes studied have very similar diffusion coefficients and the activation energy amounts to 0.46 eV, which is higher than that of Nafion (0.36 eV). Increasing the ratio of hydrophilic to hydrophobic polymer groups leads to faster diffusion in the temperature range from 273 to 355 K. For the co-PNIS membranes with the highest ratio of hydrophilic to hydrophobic groups, the proton diffusivity is about 2.3 times higher than for the Nafion 212 membrane. Unlike for Nafion-type membranes, the diffusion does not depend on the length scale of the experiment, indicating that the morphology of co-PNIS membranes may differ from the channel-like structure of Nafion membranes.
Добавил в систему: Пономарев Игорь Игоревич

	ИСТИНА	Войти в систему Регистрация
	ИПМех РАН
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

ИПМех РАН

Diffusion in Sulfonated Co-Polynaphthoyleneimide Proton Exchange Membranes with Different Ratios of Hydrophylic to Hydrophobic Groups Studied Using SFG NMRстатья

Прикрепленные файлы