Langmuir-Blodgett膜法中的流体动力学过程,Langmuir

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Langmuir-Blodgett膜法中的流体动力学过程
Langmuir ( IF 3.7 ) Pub Date : 2020-11-17 , DOI: 10.1021/acs.langmuir.0c02975
Wenjie Ji _{1,

2} , Wenjing Zhao ₃ , Weibin Li _{1,

2} , Yuren Wang _{1,

2} , Jin Wang ₃ , Ding Lan _{1,

2}

Affiliation

通过有机分子在水表面的扩散以可控的方式制备有机涂层是Langmuir-Blodgett（LB）技术研究的重点之一。为了制备均匀的膜并提高膜的质量，我们需要对铺展涉及的动态过程有更深入的了解。在这里，我们概述了在辅助铺展溶剂的影响下的流体动力学过程，主要集中在相关现象的机械机理上。为了制备LB膜，进行了典型的两组分混合液滴在水基质上的铺展实验。我们在另一种不混溶的深水基质的水平表面上进行硅油和油酸混合物液体的铺展，挥发性硅油是低粘度的辅助铺展溶剂。我们发现它需要超过某个临界值（在我们的实验中为60％）才能实现均匀且中心对称的扩展过程，这是获得均匀薄膜的关键因素。我们观察到在实验中，在表面张力梯度的作用下，大液滴演变成液膜，然后演变成小液滴。重力-粘性和表面张力-粘性在整个铺展过程中相继占主导地位，其铺展半径我们观察到在实验中，在表面张力梯度的作用下，大液滴演变成液膜，然后演变成小液滴。重力-粘性和表面张力-粘性在整个铺展过程中相继占主导地位，其铺展半径我们观察到在实验中，在表面张力梯度的作用下，大液滴演变成液膜，然后演变成小液滴。重力-粘性和表面张力-粘性在整个铺展过程中相继占主导地位，其铺展半径r（t）∝ t ^1/4和r（t）∝ t ^3/4。但是，我们还获得了缩放指数-0.033和-0.180的奇异值，这是由于毛细管波附近不同曲率引起的拉普拉斯压力分布不均匀所致。

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Hydrodynamic Process in the Langmuir-Blodgett Film Method

Preparing organic coatings in a very controlled manner through the spreading of organic molecules on the water surface is one of the emphases for research in Langmuir-Blodgett (LB) technology. For preparing a homogeneous film and improving the quality of the film, it is our concern to have a deeper understanding of the dynamic process involved in spreading. Here, we present an overview of the hydrodynamic process under the influence of assisting the spreading solvent, which mainly focuses on the mechanical mechanisms of related phenomena. A typical spreading experiment of two-component mixed droplets on water substrate for the purpose of preparing LB films was carried out in this research. We perform the spreading of a liquid of silicone oil and oleic acid mixture on the horizontal surface of another immiscible deep water substrate, where the volatile silicone oil is the assisting spreading solvent with low viscosity. We find that it needs to exceed a certain critical value (60% in our experiment) to achieve a uniform and centrosymmetric spreading process, which is a key factor for getting a homogeneous film. We observe that the evolution of a large droplet into liquid film and then into small droplets under the action of surface tension gradient in experiments. Gravity-viscous and surface tension-viscous dominate successively in the whole spreading process, with its spreading radius r(t) ∝ t^1/4 and r(t) ∝ t^3/4, respectively. However, we also obtain singular values of scaling exponents −0.033 and −0.180, which is attributed to nonuniform distribution of the Laplace pressure caused by different curvatures near the capillary wave.

更新日期：2020-12-01

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