Degradation Studies of Dielectric Materials Used in Space Environments: A Combined Experimental and Computational Approach

Kapton polyimide (PI), Mylar polyethylene terephthalate (PET), and Teflon polytetrafluoroethylene (PTFE) films are indispensable in optoelectronics, nuclear technology, and, especially, spacecraft and satellite exteriors owing to their low density, excellent dielectric strength, optical transparency, and mechanical flexibility. In order to investigate how these polymers age and degrade in the harsh space environment, this study systematically probes their internal structure, bonding chemistry, and surface morphology under simulated extreme conditions. Pristine samples were subjected to oxygen‑plasma etching for 5, 15, and 30 min at powers of 30, 100, and 200 W, combined with thermal loads of 70, 100, and 150 °C. In addition, UV irradiation and additional thermal exposure were applied to mimic solar and orbital heating cycles. Newly formed surface functionalities were tracked by FTIR and Raman spectroscopy, and surface wettability changes were quantified by contactangle measurements. SEM and AFM provided micro‑ and nano‑scale morphology and roughness data, and X‑ray diffraction quantified shifts in crystallinity and amorphous content. Structural models of these materials were obtained using first-principles calculations based on density functional theory (DFT). Charge accumulation within these models and electron transfer through them have been obtained using Bader charge analyses as well as wave function calculations of these atomistic models as obtained from DFT. We compared the compatibility of the computational models we obtained with experimental results based on diffraction patterns, bonding environment and charge characterization of the surfaces. Through this multi-technique approach, we aim to develop a deeper understanding of the chemical and physical mechanisms governing polymer degradation, with the goal of providing critical knowledge for material selection and lifetime prediction in next-generation space systems.