Influence of hydrogen bonding effects on methanol and water diffusivities in acid-base polymer blend membranes of sulfonated poly(ether ether ketone) and base tethered polysulfone.
Influence of hydrogen bonding effects on methanol and water diffusivities in acid-base polymer blend membranes of sulfonated poly(ether ether ketone) and base tethered polysulfone.
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DOI：
10.1021/jp3121512
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发表时间：
2013-04
期刊：
影响因子：
--
通讯作者：
C. V. Mahajan;V. Ganesan
中科院分区：
文献类型：
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作者：
C. V. Mahajan;V. Ganesan
采用原子分子动力学模拟研究了由磺化聚醚醚酮（SPEEK）和不同碱（2-氨基-苯并咪唑、5-氨基-苯并三唑和1h -嘧啶）的聚砜组成的酸碱聚合物共混膜的水扩散率和甲醇扩散率。与实验趋势一致，在所有基于speek的系统中，发现甲醇和水的扩散率低于Nafion。当连接在聚砜上的碱基发生变化时，发现甲醇的扩散率表现出与实验测量的交叉电流密度相同的趋势。然而，只有当我们明确地考虑到与碱的氮相连的氢与SPEEK磺酸盐的氧之间的氢键相互作用时，才能观察到这种趋势。此外，在几乎所有情况下，甲醇扩散率被发现与膜的孔径高度相关，在共混物的情况下，被发现受聚砜的砜氧和H（n -碱）之间寄生氢键相互作用强度的影响。利用配位行为和甲醇在孔内各区域的停留时间分布，合理分析了孔径对甲醇扩散行为的影响。总之，我们的研究结果揭示了甲醇在酸碱共混膜中扩散的物理化学起源，并强调了氢键相互作用在影响酸碱聚合物共混膜中甲醇运输中所起的关键作用。
Atomistic molecular dynamics simulations were used to study the water and methanol diffusivities in acid-base polymer blend membranes consisting of sulfonated poly(ether ether ketone) (SPEEK) and polysulfone tethered with different bases (2-amino-benzimidazole, 5-amino-benzotriazole, and 1H-perimidine). Consistent with experimental trends, methanol and water diffusivities in all the SPEEK-based systems were found to be lower than those in Nafion. When the base group attached to the polysulfone was varied, the methanol diffusivities were found to exhibit the same trends as observed in the experimentally measured crossover current densities. Such trends were however observed only when we explicitly accounted for hydrogen bonding interactions between the hydrogen attached to the nitrogen of the base and the oxygen of the sulfonate of SPEEK. Furthermore, in almost all cases, methanol diffusivities were found to be highly correlated with the pore sizes of the membranes, which, in the case of blends, were found to be influenced by the strength of parasitic hydrogen bonding interactions between the sulfone oxygen of polysulfone and H(N-base). The influence of pore sizes on the methanol diffusivity behavior was rationalized by using both the coordination behavior and the residence time distributions of methanol in various regions of pores. Together, our results unravel the physicochemical origins of methanol diffusivities in acid-base blend membranes and highlight the crucial role played by the hydrogen bonding interactions in influencing methanol transport in acid-base polymer blend membranes.