Development of plasma-polymer coatings for the long-term chemical resistance of plastic packaging

• Applicant: Professor Dr. Rainer Dahlmann
• Subject Area: Polymeric and Biogenic Materials and Derived Composites ; Plastics Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548883846

The research project aims to investigate the chemical resistance of plasma-polymer coating systems to strong acids and alkalis. The findings are intended to contribute to the development of fully recyclable, functional barriers for demanding fillings. Preliminary investigations have shown that coating systems with low defect density and absence of intrinsic stresses are very resistant to sodium hydroxide. In the research project, these properties will be utilized to improve the chemical resistance of plasma-polymer coating systems to hydrochloric acid. To achieve this, PECVD coating systems will be transferred from PET to HDPE bottles that can reproduce the results of alkaline media resistance. Established two-layer systems with an intermediate layer will be used to establish a sufficiently strong chemical bond between the substrate and the functional barrier. At the same time, the plant-technical requirements for performing PEALD on the reactor for hollow body inner coating will be installed. After the successful implementation of PEALD, monomers and process gases will be examined for the deposition of SiO2, SiCx, and a:Si-H layers and applied as an additional process step to the already developed coating systems. The quality of the interfaces will be given particular consideration during the integration of the processes, and the targeted adjustment of interface properties using treatment plasmas will be investigated. The resulting coating systems will be used to separately examine the identified damage mechanisms and to investigate chemically homogeneous and structurally regular coatings for their resistance to the test media due to their low defect density without the influence of physical infiltration. To draw a direct comparison between the PEALD and conventional coatings (PECVD) regarding their micro- and nanoporosity, comprehensive investigations will be conducted using electrochemical methods such as CV and EIS. The test media are intended to represent the substance groups of acids and alkalis to enable an overarching understanding of their chemical resistance to polar aqueous solutions. Overall, the research project contributes to expanding the research field of functional PECVD barriers in the area of chemical resistance and has the long-term goal of establishing fully recyclable, functional barriers for demanding fillings.

• DFG Programme: Research Grants