Université de Bordeaux, CNRS, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France.
Université de Lorraine, LCP-A2MC, 57000 Metz, France.
Langmuir. 2023 Mar 28;39(12):4216-4223. doi: 10.1021/acs.langmuir.2c02890. Epub 2023 Mar 16.
The process of convectively self-assembling particles in films suffers from low reproducibility due to its high dependency on particle concentration, as well as a variety of interactions and physical parameters. Inhomogeneities in flow rates and instabilities at the air-liquid interface are mostly responsible for reproducibility issues. These problems are aggravated by adding multiple components to the dispersion, such as binary solvent mixtures or surfactant/polymer additives, both common approaches to control stick-slip behavior. When an additive is used, not only does it change the surface tension, but also the viscosity and the evaporation rate. Worse yet, gradients in these three properties can form, which then lead to Marangoni currents. Here, we use a series of alcohols to study the role of viscosity independently of other solvent properties, to show its impact on stick-slip behavior and interband distances. We show that mixtures of glycerol and alcohol or poly(acrylic acid) and alcohol lead to more complex patterning. Marangoni currents are not always observed in co-solvent systems, being dependent on the rate of solvent evaporation. To produce homogeneous particle assemblies and control stick-slip behavior, gradients must be avoided, and the surface tension and viscosity need both be carefully controlled.
在薄膜中进行的对流自组装颗粒的过程由于其高度依赖于颗粒浓度，以及各种相互作用和物理参数，因此重复性较差。流速的不均匀性和空气-液体界面的不稳定性是造成重复性问题的主要原因。向分散体中添加多种成分，如二元溶剂混合物或表面活性剂/聚合物添加剂，都会加剧这些问题，这两种方法都是常见的控制粘滑行为的方法。当使用添加剂时，它不仅会改变表面张力，还会改变粘度和蒸发速率。更糟糕的是，这三种性质的梯度会形成，从而导致马兰戈尼电流。在这里，我们使用一系列醇来独立于其他溶剂性质研究粘度的作用，以展示其对粘滑行为和能带间距离的影响。我们表明，甘油和醇或聚丙烯酸和醇的混合物导致更复杂的图案化。马兰戈尼电流并不总是在共溶剂体系中观察到，这取决于溶剂蒸发的速率。为了产生均匀的颗粒组装并控制粘滑行为，必须避免梯度，并且需要仔细控制表面张力和粘度。
