标题： 多分散、排斥性囊泡剪切稀化的显微结构与动力学特性 显示英文标题

标题： Microscopic structure and dynamics of shear-thinning suspensions of polydisperse, repulsive vesicles

摘要： 我们研究了一种工业相关的阳离子表面活性剂囊泡分散体系的流变学、微观结构和动力学特性，覆盖了从稀到浓的各种条件。 我们发现，这些悬浮液在相对较低浓度下表现出剪切变稀行为。 在微尺度上，这对应于微观结构和动力学的明确转变：静态结构因子中出现峰值标志着结构的变化，而关联函数的动力学则减缓并呈现出双步衰减。 尽管实验表明类似组成的表面活性剂囊泡之间的相互作用应完全为排斥力，但这种低浓度下的转变却尤为令人惊讶。 这促使我们提出，观察到的结构和动力学转变可能源于大样本多分散性与拥挤效应的熵效应耦合作用。 因此，剪切变稀行为被解释为这种瞬态结构对施加流动的非线性响应。 我们的研究表明，类似的效应可能是密集且高度多分散带电悬浮液的普遍特征。 显示英文摘要

摘要： We investigate the rheology, microscopic structure, and dynamics of an industrially relevant dispersion made of cationic surfactant vesicles, from dilute to concentrated conditions. We find that these suspensions exhibit a shear-thinning behavior at relatively low concentrations. At the microscale, this corresponds to a well-defined transition in both the structure, marked by the appearance of a peak in the static structure factor, and the dynamics, which slow down and develop a two-step decay in the correlation functions. This low-concentration transition is particularly surprising in light of experiments showing that for surfactant vesicles of similar composition the interactions should be purely repulsive. This leads us to propose that the observed structural and dynamic transition could arise, as an entropic effect, from the large sample polydispersity coupled to crowding. The shear-thinning behavior is thus interpreted as the nonlinear response of this transient structure to the imposed flow. Our work suggests that similar effects might be a generic feature of dense, highly polydisperse charged suspensions.