Highly stable nano aluminum coated by self-assembled metal-phenolic network and enhancing energetic performance of nanothermite

Nano aluminum (nAl) is widely used as fuel in energetic materials owing to its high energy density. However, the highly reactive nAl is vulnerable to humidity and aqueous environment, leading to degradation of energy and limitations in practical application. Herein, the highly stable Al@TAM (M = Cu, Fe, Co, Bi) composites were prepared by coordination of tannic acid (TA) and metal ions on the surface of nAl. SEM and XRD results show that the Al@TAM composites maintain their morphology and phase composition after 14 days of immersion in water. Besides, TG tests also indicate that the Al@TAM can retain over 95 % of its active aluminum content. Molecular dynamics simulation reveals that the stable TAM layers can isolate H2O and Al2O3 and the hydrogen bonds between TA and H2O molecules can inhibit the diffusion process, thereby enhancing the stability of nano aluminum. In terms of energetic performance of Al@TAM in nanothermites, DSC results and product analyses show that the CuO/Al@TAM nanothermites exhibit higher energy release and reaction extent than that of CuO/ Al. In addition, the CuO/Al@TAM composites show higher flame intensity and maximum pressure compared to CuO/Al. Therefore, the facile coating strategy of metal-phenolic network (MPN) can stabilize aluminum in water without sacrificing the energetic performance of aluminum in CuO/Al nanothermite.