Bilyk Stepan A, Tverskoy Vladimir A, Chernyak Alexander V, Avilova Irina A, Slesarenko Nikita A, Volkov Vitaly I
Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS, 142432 Chernogolovka, Russia.
Faculty of Fundamental Physical and Chemical Engineering, Moscow State University, 119991 Moscow, Russia.
Membranes (Basel). 2023 Aug 10;13(8):725. doi: 10.3390/membranes13080725.
The hydration of ions and charge groups controls electro mass transfer through ion exchange systems. The self-diffusion and local mobility of water molecules as well as lithium cations in poly (4-styrenesulfonic acid) and its lithium, sodium and cesium salts were investigated for the first time using pulsed-field gradient NMR (PFG NMR) and NMR relaxation techniques. The temperature dependences of the water molecule and Li cation self-diffusion coefficients exhibited increasing self-diffusion activation energy in temperature regions below 0 °C, which is not due to the freezing of parts of the water. The self-diffusion coefficients of water molecules and lithium cations, as measured using PFG NMR, are in good agreement with the self-diffusion coefficients calculated based on Einstein's equation using correlation times obtained from spin-lattice relaxation data. It was shown that macroscopic water molecules' and lithium cations' transfer is controlled by local particles jumping between neighboring sulfonated groups. These results are similar to the behavior of water and cations in sulfonic cation exchanger membranes and resins. It was concluded that polystyrenesulfonic acid is appropriate model of the ionogenic part of membranes based on this polymer.
离子和电荷基团的水合作用控制着通过离子交换系统的电质量传递。首次使用脉冲场梯度核磁共振（PFG NMR）和核磁共振弛豫技术研究了聚（4-苯乙烯磺酸）及其锂盐、钠盐和铯盐中水分子以及锂阳离子的自扩散和局部迁移率。在低于0°C的温度区域，水分子和锂阳离子自扩散系数的温度依赖性表现出自扩散活化能增加，这并非由于部分水的冻结所致。使用PFG NMR测量的水分子和锂阳离子的自扩散系数，与基于爱因斯坦方程使用从自旋晶格弛豫数据获得的相关时间计算出的自扩散系数高度吻合。结果表明，宏观水分子和锂阳离子的传输受相邻磺化基团之间局部粒子跳跃的控制。这些结果与磺酸阳离子交换膜和树脂中水和阳离子的行为相似。基于此得出结论，聚苯乙烯磺酸是基于该聚合物的膜的离子ogenic部分的合适模型。
