Facile fabrication of metastable aluminum/fluoropolymer composite films by spin-coating and their thermal properties

Fluoropolymers such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) have served as potent oxidizers for aluminum (Al)-based pyrolant designs with adequate gas output and heat release. In this study, nano-Al was modified by silane coupling agent KH-570 to improve the agglomeration phenomenon, and then Al/PTFE/PVDF composite films were fabricated by a simple spin-coating method. The crystal structure, micro morphology, thermal property, and kinetic process were characterized and analyzed in detail. The results showed that Al particle size had a significant influence on the thermal property of the composite film. Micro-Al (1 μm) had an exothermic reaction with PTFE, but hardly reacted with PVDF in Al/PTFE/PVDF composite films. However, thermal decomposition reaction of PVDF occurred under the catalysis of surface Al₂O₃ when nano-Al was used. Composite films with nano-Al (50 nm and 100 nm) exhibited similar thermal behaviors. In addition, with the increase of Al content, the reaction temperature of Al₂O₃-PVDF and Al-PTFE increased slightly, and so did the total reaction heat release. Thermal kinetics calculation revealed that the apparent activation energy of Al-PTFE reaction was the highest of 139.96 kJ⋅mol⁻¹, while the reaction of Al₂O₃-PVDF occurred relatively easily. The spin-coating method used in this study was proved to have a potential application in the preparation of energetic composite films.