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Critical Role of the Atmosphere in Dip-Coating Process
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-06-29 00:00:00 , DOI: 10.1021/acs.jpcc.7b02530
Elisa Bindini 1 , Guillaume Naudin 1 , Marco Faustini 1 , David Grosso 2 , Cédric Boissière 1
Affiliation  

Dip-coating is a common liquid deposition technique employed in research, and also for industrial production, to obtain polymer, hybrid, and inorganic thin layers of controlled thickness. During liquid deposition, the substrate withdrawal speed allows, in principle, an easy tuning of deposited film thickness (first modeled by Landau and Levich). Yet, experimentally, unexplained thickness irreproducibility or strong fluctuations of the sol–gel films are often observed when coating large substrates, which is a critical issue for optical coatings such as anti-reflective/reflective coatings. In this study, we point out for the first time that uncontrolled solvent relative pressure gradients (coming from solvent evaporation) are responsible for these thickness fluctuation issues. We investigated and quantified their impact for various solutions (of sol–gel or polymer) and pointed out that the solvent evaporation rate is not constant but strongly depends on the geometric configuration of the dip-coating experiment. From this understanding, we demonstrated how an accurate tuning of processing atmosphere can provide a very good control on layer thickness in the practical case of the deposition of anti-reflective water repellent coating. In a second example, we used this phenomenon for developing a very easy synthesis strategy leading to giant and controlled thickness gradient profiles.

中文翻译:

气氛在浸涂过程中的关键作用

浸涂是用于研究以及工业生产中的常用液相沉积技术,以获得厚度可控的聚合物,杂化和无机薄层。在液体沉积过程中,从原理上讲,基板的抽出速度可轻松调整沉积膜的厚度(首先由Landau和Levich建模)。然而,从实验上讲,在涂覆大型基材时,经常会观察到无法解释的厚度不可复制性或溶胶-凝胶膜的强烈波动,这对于光学涂层(如抗反射/反射涂层)而言是一个关键问题。在这项研究中,我们首次指出不受控制的溶剂相对压力梯度(来自溶剂蒸发)是造成这些厚度波动的原因。我们调查并量化了它们对各种溶液(溶胶-凝胶或聚合物)的影响,并指出溶剂的蒸发速率不是恒定的,而在很大程度上取决于浸涂实验的几何构型。从这种理解中,我们证明了在沉积抗反射防水涂层的实际情况下,如何精确调整加工气氛可以很好地控制层厚。在第二个示例中,我们使用此现象开发了一种非常简单的合成策略,从而导致了巨大且受控的厚度梯度轮廓。我们展示了在防反射憎水涂层沉积的实际情况下,如何精确调整加工气氛可以很好地控制层厚。在第二个示例中,我们使用该现象开发了一种非常简单的合成策略,从而导致了巨大且可控的厚度梯度分布。我们展示了在防反射憎水涂层沉积的实际情况下,如何精确调整加工气氛可以很好地控制层厚。在第二个示例中,我们使用该现象开发了一种非常简单的合成策略,从而导致了巨大且可控的厚度梯度分布。
更新日期:2017-06-30
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