Towards a better understanding of the interdiffusion behavior of solution-processed polymer multilayers during drying

对于溶液加工聚合物多层应用，不同层之间的相互作用对产品质量具有决定性影响。为了生产聚合物多层，将单独的聚合物熔融并挤出或溶解在合适的溶剂中并作为“湿膜”施加，由此必须在随后的干燥步骤中除去溶剂。在湿膜加工期间，溶剂可溶解下层并引起层之间的聚合物相互扩散。取决于应用，层间扩散是期望的现象或应避免。例如，对于有机发光二极管，必须防止不同功能层之间的相互扩散以确保器件功能。在增材制造领域中，溶剂的添加可以充当增塑剂，从而能够加工具有高玻璃化转变温度的聚合物。在这种背景下，溶剂蒸发过程中的层间相互扩散是所期望的，因为它对逐层3D打印结构的粘附起着重要作用。已经对聚合物-溶剂体系和聚合物熔体中的扩散过程以及聚合物-多溶剂体系的干燥进行了一些优秀的理论和实验研究。在薄膜干燥过程中，聚合物在溶液处理的多层膜中的相互扩散迄今为止还没有成为研究工作的主题。干燥动力学将是非常重要的预测的相互扩散行为，因为聚合物的流动性是强烈依赖于薄膜的溶剂含量。据我们所知，没有相关的工作已经发表在这个问题上的literation.With拟议的研究项目，我们的目标是缩小这一差距，并制定一个基本的理解，在聚合物双层的质量传递过程，以预测和控制的相互扩散的聚合物-聚合物-溶剂系统在规定的干燥条件下。这些研究将为未来聚合物多层膜应用的生产过程提供宝贵的工具。

For solution-processed polymer multilayer applications, the interaction between the different layers is decisive for the product quality. For the production of polymer multilayers, the individual polymers are either melted and extruded or dissolved in a suitable solvent and applied as a "wet film", whereby the solvent has to be removed in a subsequent drying step. During wet film processing, the solvent can dissolve the subjacent layer and cause polymer interdiffusion between the layers. Depending on the application, layer interdiffusion is a desired phenomenon or should be avoided. For example, for organic light emitting diodes, it is essential to prevent an interdiffusion between the different functional layers to ensure device functionality. In the field of additive manufacturing, the addition of solvent can act as a plasticizer and thus enable processing of polymers with a high glass transition temperature. In this context, the interdiffusion between the layers during solvent evaporation is desired as it plays a major role for the adhesion of the layer-by-layer 3D printed structures.Some excellent theoretical and experimental research has been performed on diffusion processes in polymer-solvent systems and polymer melts, as well as on the drying of polymer-multi-solvent systems. Polymer interdiffusion in solution-processed multilayers during film drying has not been the subject of research efforts so far. The drying kinetics will be of great importance for the prediction of the interdiffusion behavior, since polymer mobility is strongly dependent on the solvent content of the film. To the best of our knowledge, no relevant work has been published on this subject in the literature.With the proposed research project, we aim to close this gap and to develop a fundamental understanding of mass transport processes in polymer double-layers in order to predict and control the interdiffusion of polymer-polymer-solvent systems under defined drying conditions. The investigations will provide an invaluable tool for the production process of polymer multilayer applications in the future.