The phase behavior of poly(ethylene oxide) (PEO) in aqueous salt solutions has been studied many times but rarely for solution conditions relevant to the hydration process of cement, where PEO's interactions with surrounding ions modulate its application as both plasticizer and strength‐building additive. Here, the conformation, that is, coil size, of PEO was examined in aqueous solutions in the presence of sodium‐, calcium‐ and aluminum‐containing salts. Ion‐induced conformational changes for a model linear PEO were mostly unremarkable and consistent with past reports. However, trends for aluminum‐containing ions, which predominantly occur in water at neutral and basic pH as the monovalent hydroxo‐aluminate anion Al(OH)₄⁻, were different: either present as the sodium or calcium salt, PEO's hydrodynamic radius determined by dynamic light scattering was approximately 30% larger than determined by intrinsic viscosity. The intrinsic viscosity was similar to that measured in the presence of simpler monovalent anions. We hypothesize that aluminum containing ions weakly couple the model polymer's hydroxyl end groups (present at just one chain end), creating polymeric aggregates sensitive to disruption by shearing. Supporting our argument, the hydrodynamic radius determined by dynamic light scattering dropped to the intrinsic viscosity value after hydroxyl groups were converted to methoxy groups.

中文翻译：

---

铝离子对溶解的聚环氧乙烷的剪切敏感链扩展

聚环氧乙烷（PEO）在盐水溶液中的相行为已被研究了很多次，但很少涉及与水泥水化过程有关的溶液条件，其中PEO与周围离子的相互作用调节了其在增塑剂和强度增强方面的应用添加剂。在此，在含有钠，钙和铝盐的水溶液中检查了PEO的构象，即盘绕尺寸。模型线性PEO的离子诱导构象变化几乎没有什么变化，并且与过去的报道一致。然而，趋势含铝离子，其在中性和碱性pH作为一价羟铝酸盐阴离子的Al（OH）主要发生在水中的₄ ^-的不同之处在于：以钠盐或钙盐形式存在时，通过动态光散射测定的PEO的流体力学半径比通过特性粘度测定的PEO的流体力学半径大约大30％。特性粘度类似于在较简单的一价阴离子存在下测得的特性粘度。我们假设含铝离子弱耦合模型聚合物的羟基端基（仅存在于一个链端），从而形成对剪切破坏敏感的聚合物聚集体。支持我们的观点，在羟基转化为甲氧基后，由动态光散射确定的流体力学半径下降至特性粘度值。