Healing materials for harsh space environments. Intrinsic self-healing copolyimides for lunar exploration

Future lunar exploration missions pose critical challenges for polymeric materials due to the severe degradation caused by adhesive and highly abrasive lunar regolith. Conventional fully aromatic polyimides (PIs), although widely used in space for their excellent thermo-mechanical stability, low outgassing, and chemical resistance, possess rigid backbones that prevent intrinsic self-healing and promote progressive surface degradation. In this work, semi-aromatic branched copolyimides (coPIs) with intrinsic self-healing ability are developed by tailoring the stoichiometric ratio between aromatic and aliphatic monomers. The aromatic fraction enhances thermo-mechanical stability, whereas the aliphatic fraction promotes chain mobility and self-healing through supramolecular interactions. The thermo-optical properties were investigated in terms of solar absorptance and emittance. The chemical structure was confirmed by Fourier transform infrared spectroscopy (FTIR), whereas thermal stability and self-healing performance were investigated by thermogravimetric analysis (TGA) and confocal microscopy, respectively. The self-healing capability of the membranes was also investigated after VUV irradiation and thermal cycling (20 cycles from -80 °C to 125 °C). The developed coPIs combine good thermal stability, and efficient thermally activated intrinsic self-healing, demonstrating their potential as multifunctional materials for long-duration lunar exploration missions.