Structure-Engineered Mesoporous AlSi/P(VDF-HFP) Energetic Composites with Diffusion-Enhanced Reactivity

Aluminum (Al)-based alloys have emerged as promising solid fuels for energetic composites (ECs) owing to their multi-metallic properties. However, their energy release efficiency is severely limited by diffusion-controlled reaction kinetics. In this work, a novel functionalized mesoporous AlSi alloy fuel is designed via a sequential etching and fluorination strategy and combined with P(VDF-HFP) to form AlSi/P(VDF-HFP) ECs. This structure-engineered design effectively overcomes the kinetic constraints imposed by sluggish diffusion. The mesoporous Si framework catalyzes the decomposition of P(VDF-HFP) and provides abundant channels for gas transport. Moreover, the dissociation and recombination of F^- on the fluorinated surface are analyzed by XPS, and molecular dynamics calculation shows a stronger binding capability between grafted fluorinated chains and P(VDF-HFP) through intensive C─F···F─C and C─F···H─C interactions. Remarkably, the optimized ECs exhibit a significant increase in reaction heat compared to the pristine composites, accompanied by a reduction in activation energy. Ignition and closed-bomb tests further demonstrate substantially enhanced combustion performance and pressurization capability. Based on experimental evidence, a reaction mechanism is proposed. This work provides an accessible pathway for improving the reactivity of alloy-based ECs.