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

• Applicant: Professor Dr.-Ing. Wilhelm Schabel
• Subject Area: Plastics Engineering ; Chemical and Thermal Process Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456056036

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.

• DFG Programme: Research Grants
• Co-Investigator: Dr.-Ing. Philip Scharfer