Mechanistic Insights into Enhanced Combustion of a GAP-Coated Boron Nanoparticle

Boron nanoparticles hold great potential for applications in high-energy fuels, but their practical use suffers from limited combustion performance. Glycidyl azide polymer (GAP) is a promising coating material for boron that can improve its ignition and combustion characteristics. Here, ReaxFF-based molecular dynamics simulations are used to explore the fundamental mechanisms underlying the combustion enhancement of a boron nanoparticle (BNP) coated with GAP. The experimentally observed two-stage combustion behavior of both BNP and BNP@GAP was reproduced. The results show that the GAP coating enhances both Stages I and II of the reaction, thereby improving the overall combustion performance of BNP. The enhancement of Stage I is attributed to two factors. First, the energetic GAP decomposition releases substantial heat that accelerates the temperature rise and the oxide layer evaporation. Second, the initial reaction between the oxide layer and GAP enables the bonded portion of the oxide layer to be liberated along with the GAP decomposition products, thus facilitating the oxide layer consumption. The enhancement of Stage II arises from the surface reactions between GAP-derived intermediates and the nanoparticle, which promote the nanoparticle consumption and accelerate the combustion process. Additionally, the GAP-derived species also play crucial roles in gas-phase reactions in the BNP@GAP system. These atomic-scale findings provide a mechanistic basis for developing energetic-material-coated BNP in the field of high-energy fuels.