Specifics of solvation of sulfonated polyelectrolytes in water, dimethylmethylphosphonate, and their mixture: a molecular simulation study.
Specifics of solvation of sulfonated polyelectrolytes in water, dimethylmethylphosphonate, and their mixture: a molecular simulation study.
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磺化聚电解质在水、甲基膦酸二甲酯及其混合物中的溶剂化特性：分子模拟研究。
DOI：
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发表时间：
2008
影响因子：
4.4
通讯作者：
A. Neimark
中科院分区：
文献类型：
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作者：
A. Vishnyakov;A. Neimark
磺化聚电解质膜（PEMs），如Nafion和苯乙烯-烯烃嵌段共聚物，被探索作为燃料电池的过选择性膜，以及合适的化学试剂屏障材料。PEM的超选择性是由其微相分离成亲水性和疏水性结构域决定的。我们对质子交换膜亲水性片段在磺化聚苯乙烯（sPS）上的溶剂化进行了经典的分子动力学模拟，以钾、钙和铝为反离子，在水、磷-有机神经毒剂模拟二甲基膦酸盐（DMMP）及其二元混合物中进行溶剂化。通过优化势参数，拟合密度泛函理论得到的苯磺酸盐构象，得到了磺酸基的力场。为了进行比较，我们考虑了代表Nafion聚合物片段的全氟磺酸低聚物。我们发现在不同溶剂中聚合物主链的几何形状有明显的不同。在DMMP中，sPS和Nafion的聚合物骨架都更硬。由于苯基磺酸基的刚性和各向异性，溶剂在苯基磺酸基周围的各向异性结构比在nafon侧链周围的结构强得多。反离子显著影响溶剂化sPS的构象：当钾离子或钙离子被三价铝离子取代时，主干的刚性增加。
Sulfonated polyelectrolyte membranes (PEMs), such as Nafion and styrene-olefin block copolymers, are explored as permselective membranes for fuel cells as well as suitable barrier materials against chemical agents. The permselective properties of PEM are determined by their microphase segregation into hydrophilic and hydrophobic domains. We performed classical molecular dynamics simulations of solvation of the hydrophilic fragments of PEM exemplified on sulfonated polystyrene (sPS) with potassium, calcium, and aluminum as counterions, in water, phosphor-organic nerve agent simulant dimethylmethylphosphonate (DMMP), and their binary mixture. The force field for the sulfonate group has been developed by optimizing the potential parameters to fit the benzenesulfonate conformations obtained from the density functional theory. For a comparison, we considered perfluorosulfonate oligomers representing fragments of Nafion polymer. We found a noticeable difference between the geometries of the polymer backbone in different solvents. The polymer backbone is stiffer in DMMP for both sPS and Nafion. An anisotropic structuring of the solvent around the phenylsulfonate group is substantially stronger than around the Nafion sidechain due to the rigidity and the anisotropy of the phenylsulfonate group. The counterion significantly affects the conformations of solvated sPS: the rigidity of the backbone increases when potassium or calcium ions are replaced by trivalent aluminum ions.