In this work, we have investigated a pH-modulated complexation between two oppositely charged strong polyelectrolytes to demonstrate the effect of counterion-mediated hydrogen bonding (CMHB) on polyelectrolyte complexation. We have found that such a pH-modulated complexation cannot be understood without considering the CMHB. Thermodynamically, the effect of CMHB on the polyelectrolyte complexation is manifested by the alteration of both enthalpic and entropic contributions to the free energy change. The pH-dependent intrinsic ion-pairing and complex coacervation processes of the polyelectrolyte complexation can be understood when considering the CMHB. Our study demonstrates that both the extent of polyelectrolyte complex formation in bulk solutions and the formation of polyelectrolyte multilayers on surfaces are controlled by the pH-dependent intrinsic ion-pairing process. Furthermore, on the basis of the pH-dependent intrinsic ion pairing, the properties of the multilayers can be tuned by pH. This work provides a new strategy to control the polyelectrolyte complexation with counterions and will inspire new ideas for building advanced polyelectrolyte materials.

中文翻译：

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考虑反离子介导的氢键时的聚电解质络合

在这项工作中，我们研究了两种带相反电荷的强聚电解质之间的 pH 调节络合，以证明抗衡离子介导的氢键 (CMHB) 对聚电解质络合的影响。我们发现，如果不考虑 CMHB，就无法理解这种 pH 调节的络合。在热力学上，CMHB 对聚电解质络合的影响表现为焓和熵对自由能变化的贡献的改变。当考虑 CMHB 时，可以理解聚电解质络合的 pH 依赖性固有离子对和复杂的凝聚过程。我们的研究表明，本体溶液中聚电解质复合物形成的程度和表面上聚电解质多层的形成均受 pH 依赖性固有离子对过程的控制。此外，基于依赖于 pH 的本征离子对，可以通过 pH 调节多层膜的性质。这项工作提供了一种控制聚电解质与抗衡离子络合的新策略，并将激发构建先进聚电解质材料的新思路。