Perfluoroalkyl Acid-Functionalized Aluminum Nanoparticles for Fluorine Fixation and Energy Generation

Aluminum nanoparticle (nAl) has a promising application prospect in energetic materials (EMs) due to its high reactivity. However, some issues like agglomeration and oxide layers seriously affect its performances. To actualize the potential of nAl, perfluoroalkyl acids (PFAAs) with different molecular structures were introduced into nAl-based EMs for surface functionalization in the current work. The energy performances of nAl/PFAAs including flame propagation features and heat release were investigated in different atmospheres, and the related fluorine fixation ratio (FFR) was also obtained. Results show that both the energy performances and the FFR were improved with the increase of the skeleton chain length and the fluorine content of PFAAs. Although the heat release is higher in air, FFR in air is apparently lower than that in N2. Possible reaction mechanisms were probed by the in-situ monitoring of the gaseous and condensed products from thermal decomposition. This reveals that the oxide layer was first corroded by carboxyl, and fluorocarbons were generated succeeded by the fluorination of exposed Al. The most reactive intermediates are CFx free radicals, which dominates the initial interaction.