Quasi-immiscible spreading of aqueous surfactant solutions on entangled aqueous polymer solution subphases.
Quasi-immiscible spreading of aqueous surfactant solutions on entangled aqueous polymer solution subphases.
复制标题
表面活性剂水溶液在缠结的聚合物水溶液亚相上的准不混溶铺展。
DOI：
10.1021/am400762q
复制
发表时间：
2013
影响因子：
9.5
通讯作者：
Tilton,RobertD
中科院分区：
文献类型：
--
作者：
Sharma,Ramankur;Corcoran,TimothyE;Garoff,Stephen;Przybycien,ToddM;Swanson,EllenR;Tilton,RobertD
出于增强气雾剂药物递送到粘液阻塞的肺的可能性，研究了一滴表面活性剂水溶液在物理缠结的聚丙烯酰胺水溶液亚相上的扩散，所述聚丙烯酰胺水溶液亚相模拟肺气道表面液体。十二烷基硫酸钠用作表面活性剂。为了可视化液滴的扩散并模拟药物物质的包含，将荧光素（一种亲水性和非表面活性染料）加入表面活性剂溶液中。传播是通过一系列事件进行的。Marangoni应力引发液滴的对流扩散。同时，表面活性剂在沉积的一秒钟内穿过液滴的接触线逃逸，并导致液滴外部的亚相表面张力的变化为1 mN/m。当达到新的界面张力平衡时，液滴的对流扩散在液滴沉积的2-3秒内结束。表面活性剂逸出耗尽表面活性剂液滴，并且残余液滴采取非零接触角的静态透镜的形式。在较长的时间尺度上，表面活性剂溶解到亚相中。由沉积液滴中的水形成的透镜在对流扩散过程结束后持续长达3分钟，这是由于与下面的缠结聚合物溶液相关的长扩散时间尺度。透镜的持久性表明，在该时间段期间，液滴相表现得好像与亚相不混溶。而表面活性剂逃逸的扩散液滴和亚相/蒸汽界面上的进步，在滴中的亲水性染料分子不逃逸，但保持与整个对流扩散的滴。的准不混溶性质的扩散事件表明，表面活性剂和亚相的化学性质是远不如它们的物理性质重要，与以前的定性研究的不同类型的表面活性剂的缠结聚合物亚相上的扩散一致：选择的表面活性剂用于肺部输送应用可能只限于物理和毒理学的考虑。此外，表面活性剂从单个液滴中的逃逸可以在肺中提供额外的扩散机制，因为流体动力学和/或表面压力排斥可以在沉积后驱动单个液滴分开。
Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface-active dye, was added to the surfactant solution. The spreading progresses through a series of events. Marangoni stresses initiate the convective spreading of the drop. Simultaneously, surfactant escapes across the drop’s contact line within a second of deposition and causes a change in subphase surface tension outside the drop on the order of 1 mN/m. Convective spreading of the drop ends within 2–3 s of drop deposition, when a new interfacial tension balance is achieved. Surfactant escape depletes the drop of surfactant, and the residual drop takes the form of a static lens of nonzero contact angle. On longer time scales, the surfactant dissolves into the subphase. The lens formed by the water in the deposited drop persists for as long as 3 min after the convective spreading process ends due to the long diffusional time scales associated with the underlying entangled polymer solution. The persistence of the lens suggests that the drop phase behaves as if it were immiscible with the subphase during this time period. Whereas surfactant escapes the spreading drop and advances on the subphase/vapor interface, hydrophilic dye molecules in the drop do not escape but remain with the drop throughout the convective spreading. The quasi-immiscible nature of the spreading event suggests that the chemical properties of the surfactant and subphase are much less important than their physical properties, consistent with prior qualitative studies of spreading of different types of surfactants on entangled polymer subphases: the selection of surfactant for pulmonary delivery applications may be limited only by physical and toxicological considerations. Further, the escape of surfactant from individual drops may provide an additional spreading mechanism in the lung, as hydrodynamic and/or surface pressure repulsions may drive individual droplets apart after deposition.