Employing Instabilities in Large Area Thin-Film Coating with Complex Fluids

本项目旨在了解和应用从根本上限制快速工业均匀薄膜涂层的不稳定机制，重点是(1)刀片涂层和(2)槽模涂层技术。这些方法不需要高真空条件，因此适用于对高速工业表面处理非常重要的卷对卷生产。然而，根据流体和基材的性质和工艺参数的不同，会发生导致涂层缺陷和图案化涂层的不稳定性。例如，如果涂层厚度低于临界厚度，则较大的涂层速度可能会导致涂层破裂。我们的目标是了解简单的非挥发性和挥发性液体以及作为聚合物溶液和纳米颗粒悬浮液的复杂液体的各种不稳定机制和由此产生的自组织结构和模式。我们计划分析被动控制策略，使人们能够通过调整系统的控制参数来微调所产生的涂层图案的特征。最后，我们将开发利用同步效应的主动控制策略，通过对镀膜过程的控制参数的时间调制来施加结构长度。在所有阶段，该项目都将在理论(理论物理研究所、威斯夫-威廉姆斯-明斯特大学，WWU)和实验(Lehrstuhl für Laseranwendungstechnik、Ruhr-Unversetät Bochum、RUB)之间的密切合作下进行。

This project aims at understanding and employing the instability mechanisms that fundamentally limit rapid industrial uniform thin-film coating focusing on (1) blade coating and (2) slot-die coating techniques. These methods do not require high vacuum conditions and, therefore, are suitable for roll-to-roll production that is important for high-speed industrial surface processing. However, depending on fluid and substrate properties and process parameters, instabilities occur that result in coating defects and patterned coatings. For instance, a large coating velocity may induce breaking of the coating film if its thickness is below a critical one. We aim at understanding the various instability mechanisms and the resulting self-organised structures and patterns for simple non-volatile and volatile liquids as well as for complex liquids as polymer solutions and nanoparticle suspensions. We plan to analyse passive control strategies that allow one to fine tune the features of the resulting coating patterns by adjusting the control parameters of the system. Finally we will develop active control strategies that employ synchronisation effects to impose structure length by temporal modulaton of control parameters of the coating processes. In all stages, the project will be pursued in close cooperation between theory (Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, WWU) and experiment (Lehrstuhl für Laseranwendungstechnik, Ruhr-Unversität Bochum, RUB).