Cationic separating the with different valence states is greatly desirable but technically challenging. Achieving such a precise separation using membranes requires accurately distinguishing tiny differences of cations on physico-chemical properties. Here, inspired by the ion dehydration effect, a series of cation exchange membrane with adjustable surface hydrophobicity based on quaternized polypyrrole were prepared. We demonstrate that improving hydrophobicity of modified layer substantially hinder cations with higher hydration energy to enter the modified layer due to their stronger binding ability with water molecules. When applied in electro-driven cation separation, the optimal membrane exhibited an outstanding perm-selectivity between monovalent and divalent cations (P^Na_Mg = 12.95, P^Li_Mg = 1.28) than commercial monovalent cation perm-selective membrane (P^Na_Mg = 2.46, P^Li_Mg = 1.07). Overall, our results indicate that the hydrophobicity of the modified layer governs the cations dehydration behavior through the polymeric pores due to ion-pore wall interactions, providing the scientific basis for the construction of membranes with high monovalent cation perm-selectivity.

阳离子分离具有不同化合价态是非常需要的，但是在技术上具有挑战性。使用膜实现如此精确的分离需要准确区分阳离子在物理化学性质上的微小差异。在此，受离子脱水作用的启发，制备了一系列基于季铵化聚吡咯的表面疏水性可调节的阳离子交换膜。我们证明改进改性层的疏水性实质上阻碍了阳离子以较高的水合能进入改性层，因为它们与水分子的结合能力更强。当应用于电驱动阳离子分离时，最佳膜在单价和二价阳离子之间表现出出色的渗透选择性（P ^Na _Mg  = 12.95，P^Li _Mg  = 1.28）比市售单价阳离子渗透选择性膜（P ^Na _Mg  = 2.46，P ^Li _Mg  = 1.07）。总的来说，我们的结果表明，由于离子孔壁的相互作用，改性层的疏水性决定了阳离子通过聚合物孔的脱水行为，为构建具有高单价阳离子渗透选择性的膜提供了科学依据。