Fluorinated Polyimide/Sepia Eumelanin Nanocomposites for Aerospace Applications

Natural marine sepia eumelanin-derived additives (ASE) were used as a filler to modify highly fluorinated polyimide (FPI), acquiring the enhanced comprehensive performance by chemical bonding and pore structure construction. Stress-strain curves indicated an optimal tensile strength of 108.25 MPa and a fracture elongation of 4.83% (1 wt % ASE), respectively, 1.30 and 1.34x that of pure FPI. Thermal analysis showed that Tg was as high as 360.1, 14.4 degrees C higher than that of pristine FPI. The exceptional UV-shielding capabilities of the FPI/ASE films were confirmed by measurements of curcumin photodegradation, durability, and so on. FTIR and AFM manifested their superior photostability with basically unchanged carbonyl absorption peaks and much less variation in surface roughness after UV exposure for 720 h. To sum up, the covalent network structure between FPI and ASE contributed to the improvement of mechanical and thermal properties. The mechanisms, such as synergistic UV absorption of FPI and ASE, photothermal conversion, and ASE's free radical trapping ability, were responsible for the remarkable UV-shielding and light stability. The above remarkable comprehensive performance makes the FPI/ASE film a candidate for UV shielding in aerospace applications.