Research Institute for Computational Sciences, National Institute of Advanced Industrial Science and Technology, Centeral-2, Umezono 1-1-1, Tsukuba 305-8578, Japan.
J Phys Chem B. 2010 Feb 25;114(7):2411-21. doi: 10.1021/jp906757s.
The nature of proton dynamics as well as a pendant side chain's ability for proton dissociation and capture in low-hydration sulfonated polyethersulfone (SPES) (lambda = 2, 4) have been studied theoretically by means of quantum chemical calculations and first-principles molecular dynamics simulations. A detailed comparison of results on SPES with those on Nafion has been made. It is found that the sulfonic groups of Nafion tend to dissociate protons more easily than do those of SPES. Hydration by four water molecules allows the dissociation of a proton from the sulfonic groups in both SPES and Nafion. The results of the first-principles MD simulations on SPES show that the nature of proton transfer kinetics for both hydration levels is very similar. Compared with low-hydration Nafion, however, hydration around the sulfonic groups in SPES is not sufficient to fully dissociate protons from the sulfonic groups, which results from the fact that some of the water molecules participate in hydrating SO(2) groups in SPES rather than SO(3)(-). Such a feature affects the performance of SPES under low-hydration conditions.
质子动力学的本质以及侧挂基团在低水合磺化聚醚砜（SPES）（lambda = 2, 4）中质子离解和捕获的能力已经通过量子化学计算和第一性原理分子动力学模拟进行了理论研究。对 SPES 和 Nafion 的结果进行了详细的比较。结果表明，Nafion 的磺酸基团比 SPES 的更容易离解质子。通过四个水分子的水合作用可以使 SPES 和 Nafion 的磺酸基团中的质子解离。对 SPES 的第一性原理 MD 模拟的结果表明，两种水合水平的质子转移动力学的性质非常相似。然而，与低水合 Nafion 相比，SPES 中磺酸基团周围的水合作用不足以将质子完全从磺酸基团中离解出来，这是因为一些水分子参与了 SPES 中 SO(2)基团的水合作用，而不是 SO(3)(-)。这种特征会影响 SPES 在低水合条件下的性能。
