Eco-friendly synthesis of high-performance polyimide materials using bio-based greener solvents. Towards sustainable technologies in space environment

Polyimide-based materials offer high thermal stability, mechanical strength, and resistance to UV and solar radiation, making them ideal candidates for use in demanding space missions. In particular, polyimide membranes find practical application in large deployable and inflatable structures, as well as in solar propulsion sails for deep space missions. In this work, thermally stable polyimides with fully aromatic structure and trifluoromethyl functional groups were synthesized by a two-step method using bio-based alternative solvents, namely dimethyl isosorbide (DMI) and dihydrolevoglucosenone (Cyrene). These solvents are considered environmentally friendly and greener alternatives compared to conventional dipolar aprotic solvents like dimethylacetamide (DMAc). Using the in-house-made aromatic polyimides, membranes were fabricated and their properties were compared to those made of PI synthesized using conventional routes in DMAc. Different routes for solvent removal were investigated during membrane fabrication. Several key characteristics were considered to assess the effect of using greener solvents on the final properties of the polyimide materials, including hydrophobicity degree from water contact angle (WCA), thermal behavior from differential scanning calorimetry (DSC), and viscoelastic properties from dynamic-mechanical analysis (DMA). These analyses provide insights into the thermal and mechanical response of the PI materials under varying temperatures and loads, which is essential for designing structures that can withstand the harsh conditions of space, such as in solar sail propulsion systems.