Interfacial Engineering of Al-NH4CoF3@P(VDF-HFP) Core-Shell Energetic Composites via Electrostatic Spraying: Enhanced Stability and Combustion Performance

Al/NH 4 CoF 3 - Φ ( Φ = 0.5, 1.0, 1.5, 2.0 and 3.0) binary composites and Al-NH 4 CoF 3 @P(VDF-HFP) ternary composites are fabricated via ultrasonication-assisted blending and electrostatic spraying. The effect of equivalence ratio ( Φ ) on the reaction properties is systematically investigated in the binary Al/NH 4 CoF 3 system. For ternary systems, electrostatic spraying allows both components to be efficiently encapsulated by P(VDF-HFP) and to achieve structural stabilization and enhanced reactivity through synergistic interfacial interactions. Morphological analysis using SEM/TEM revealed that P(VDF-HFP) formed a protective layer on Al and NH 4 CoF 3 particles, improving dispersion, hydrophobicity (water contact angle increased by 80.5% compared to physically mixed composites) and corrosion resistance. Thermal decomposition of NH 4 CoF 3 occurred at 265 °C, releasing NH 3 and HF, which triggered exothermic reactions with Al. The ternary composites exhibited a narrowed main reaction temperature range and concentrated heat release, attributed to improved interfacial contact and polymer decomposition. Combustion tests demonstrated that Al-NH 4 CoF 3 @P(VDF-HFP) achieved self-sustaining combustion. In addition, a simple validation was done by replacing the Al component in the aluminium-containing propellant, demonstrating its potential application in the propellant field. This work establishes a novel strategy for designing stable, high-energy composites with potential applications in advanced propulsion systems.