Investigation of the Degradation of Fluoropolymer Materials in a Low Temperature Oxygen Plasma using Physical-Chemical Surface Analysis

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WagnerTobias-2026-06-25.pdf (44.85 MB)

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2026

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DOI:
https://doi.org/10.22029/jlupub-21001

Abstract

The low Earth orbit (LEO) plays an important role for space exploration, modern telecommunication and Earth observation. While the proximity to Earth makes the LEO particularly attractive for these applications, the environmental conditions inside the LEO are harsh and can lead to rapid material degradation. Many satellites remain in the LEO for years and even decades, increasing the chance for catastrophic material failure during its lifecycle. One significant threat to materials in the LEO is atomic oxygen (AO), which is the most abundant species of gas in parts of the LEO and extremely reactive. Understanding the chemical degradation that occurs when a surface is in contact with AO is crucial for improving material design for applications in the LEO. To generate AO and partially simulate LEO conditions, low temperature oxygen plasmas are commonly employed. Fluoropolymers have favorable features for use in the LEO. Among these are low density, thermal and electrical insulating properties and a relatively high resistance towards AO, compared to other polymers. Most studies investigating the degradation of fluoropolymers and other materials in space focus on changing mechanical properties. Physical-chemical characterization methods are utilized much more sparingly, leading to a gap in the knowledge about the chemical processes at the surface of materials exposed to LEO conditions. In the framework of this doctoral thesis the chemical degradation of two fluoropolymers, polyvinyl fluoride (PVF) and polytetrafluoroethylene (PTFE), in a low temperature oxygen plasma was investigated. The latter is often employed in the LEO as a wiring insulator on the exterior of spacecraft, coming in contact with AO. The former is used less frequently in space applications and was chosen as a less fluorinated reference material. The degradation mechanism was studied by employing surface sensitive chemical analysis techniques such as time-of-flight secondary-ion mass spectrometry (ToF–SIMS) and X-ray photoelectron spectroscopy (XPS) on the sample, as well as by monitoring the plasma composition via quadrupole mass spectrometry (QMS). Multivariate statistical (MVS) tools were used to obtain a deeper understanding of the measurement data. By ToF–SIMS and XPS measurements, degradation products on the sample surface were identified, while QMS measurements revealed unoxygenated carbon species in the atmosphere, indicating incomplete oxidation. Overall, the results of this doctoral thesis expand the knowledge about the chemical processes involved in the degradation of fluoropolymers under space-like conditions. The use of methods for chemical surface analysis techniques in this work yields a significant benefit for the investigation of material degradation under space-like conditions that is currently not fully realized. Additionally, the insight gained into the measurement data by the use of MVS tools for data evaluation demonstrates their usefulness to assist in answering a variety of scientific questions.

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