We report on shear startup data for two wormlike micellar solutions, differing only in concentration and type of two binding aromatic sodium salts. The surfactant molecule is cetylpiridinium chloride at a fixed concentration (100 mM). Sodium salicylate (NaSal) and diclofenac sodium (Diclo) are used as binding salts at concentrations 68 mM NaSal and 52 mM Diclo such that both systems are fully entangled and their linear viscoelastic response is essentially identical. Both systems show the linear response typical of a wormlike micellar solution, with terminal behavior at low frequencies, a well-defined moduli crossover, and a plateau modulus. In the nonlinear regime, however, the behavior of the two systems is totally different, suggesting that the molecular structure difference of the salts and their binding activity to the surfactant molecule are both crucial to determine the fast flow behavior. The NaSal solution shows a very complex rheological response, with strain hardening and very sharp stress peaks, whereas the solution containing Diclo behaves much like ordinary linear polymers, exhibiting pronounced overshoots as well as moderate undershoots in the transient shear viscosity, before approaching the steady state. This polymerlike behavior has also been proved by successfully comparing data with predictions of a constitutive equation recently adopted for both entangled polymers and linear wormlike micelles. As far as NaSal is concerned, a phenomenological model based on rubber network theory is developed, which describes the flow singularities. A physical interpretation of the different behavior in the nonlinear regime is also suggested.

中文翻译：

---

蠕虫状胶束网络的启动行为：不同盐类与同一表面活性剂分子结合的影响

我们报告了两种蠕虫状胶束溶液的剪切启动数据，仅在两种结合芳香钠盐的浓度和类型上有所不同。表面活性剂分子是固定浓度 (100 mM) 的氯化十六烷基吡啶。水杨酸钠 (NaSal) 和双氯芬酸钠 (Diclo) 用作浓度为 68 mM NaSal 和 52 mM Diclo 的结合盐，这样两个系统完全缠结并且它们的线性粘弹性响应基本相同。这两个系统都显示出典型的蠕虫状胶束溶液的线性响应，具有低频下的终端行为、明确定义的模量交叉和平台模量。然而，在非线性状态下，两个系统的行为完全不同，表明盐的分子结构差异及其与表面活性剂分子的结合活性对于确定快速流动行为都是至关重要的。NaSal 溶液表现出非常复杂的流变响应，具有应变硬化和非常尖锐的应力峰，而含有 Diclo 的溶液表现得非常像普通线性聚合物，在接近稳态之前，瞬态剪切粘度表现出明显的过冲和适度的下冲. 通过成功地将数据与最近采用的纠缠聚合物和线性蠕虫状胶束的本构方程的预测进行比较，也证明了这种类似聚合物的行为。就 NaSal 而言，开发了一种基于橡胶网络理论的现象学模型，该模型描述了流动奇点。