Energetic composites based on nano-Al and energetic coordination polymers (ECPs): The “father-son” effect of ECPs

The limited gas production of Al/metal oxide-based thermites due to lack of gas elements (e.g., C, H, and N) greatly hinders its practical application. By contrast, energetic coordination polymers (ECPs) are rich in gas elements from organic ligands and have the potential to rapidly decompose into corresponding metal oxides with a large amount of heat output. In this work, a novel high-performance energetic material based on Al/ECPs is presented. Al/ECPs binary energetic composites have enhanced heat release, pressure production, and combustion performance owing to the contribution of the “father” ECPs’ thermal decomposition reaction and the “son” metal oxide's thermite reaction with nano-Al. [Mn(BTO)(H₂O)₂]_n (BTO = 1H,1′H-[5,5′-bitetrazole]-1,1′-bis(olate)) is used as a typical ECP and composited with nano-Al. The exothermic peak of the thermite reaction between 520 °C and 730 °C on the differential scanning calorimetry curves contributes to the high heat output of the Al/[Mn(BTO)(H₂O)₂]_n energetic composites, especially when the molar ratio of Al/Mn is 1.0 (2189.6 J/g). The peak pressure of this composite (3.6 MPa) is 1.5 times as high as that of traditional nanothermite (Al/CuO) with much longer high-pressure duration in the closed bomb experiments. It also exhibits very intense burning and long duration (around 300 ms) in opening burning experiments. These results prove that the father-son effect of ECPs is highly significant in developing new-concept Al/ECPs energetic materials for gas generation, heat release and combustion.