The effect of complexation pH and water on the relaxation time and dynamics of polyelectrolyte (PE) complexes (PECs) and coacervates remains poorly understood. Here, we describe the dynamic mechanical behavior of solid-like PECs containing weak PEs poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) at varying complexation pH, relative humidity, and temperature with support from molecular dynamics simulations. Time–temperature, time–water, and time–intrinsic ion pair superposition principles are applied to obtain the relaxation times. It is shown that the natural log of relaxation time in hydrated PAH/PAA PECs is inversely proportional to the volume fraction of water (ln τ ∼ ϕ_w^–1) for a given complexation pH. For all complexation pH values examined, the natural log of relaxation time collapsed into a single line when plotted against the ratio of the number of intrinsic ion pairs to water molecules (ln (τ) ∼ n_{intrinsic ion pairs}/n_water). Taken together, this suggests that the relaxation of solid-like, hydrated PAH/PAA PECs is mediated by bound water at the intrinsic ion pair.

中文翻译：

---

不同pH值和水含量的类固体聚电解质复合物的弛豫时间

络合 pH 值和水对聚电解质 (PE) 复合物 (PEC) 和凝聚层的弛豫时间和动力学的影响仍然知之甚少。在这里，我们在分子动力学模拟的支持下描述了含有弱 PE 聚（烯丙胺盐酸盐）（PAH）和聚（丙烯酸）（PAA）的固体状 PEC 在不同的络合 pH、相对湿度和温度下的动态机械行为。应用时间-温度、时间-水和时间-本征离子对叠加原理来获得弛豫时间。结果表明，水合 PAH/PAA PEC 中弛豫时间的自然对数与水的体积分数成反比 (ln τ ∼ ϕ _w ^–1) 对于给定的络合 pH。对于所有检测的络合 pH 值，当根据本征离子对与水分子的数量之比（ln (τ) ∼ n_{本征离子对}/ n_水）作图时，弛豫时间的自然对数折叠成一条线。总之，这表明固体状水合 PAH/PAA PEC 的弛豫是由内在离子对处的结合水介导的。