Can the gradient distribution and antimigration of deterrents in nitrocellulose-based propellant be balanced?: A strategy for small molecule diffusion followed by UV-induced curing

Abstract

To address the issue of deterrent migration in current nitrocellulose-based propellant, this study designed a UV-curable deterrent. The deterrent precursor penetrates the propellant to a certain depth, after which UV irradiation induces a curing reaction, producing a UV-curable deterrent propellant. Scanning electron microscopy, energy-dispersive spectroscopy, and confocal laser Raman spectroscopy (Raman) were employed to observe the surface morphology of the UV-cured deterrent propellant and analyze the elemental distribution of its surface and internal structural composition. Additionally, thermogravimetric–differential scanning calorimetry was used to investigate the impact of the UV-curable deterrent on the thermal decomposition performance of the propellant and to evaluate its compatibility with the propellant. Molecular dynamics simulations were further conducted to examine the diffusion behavior of the deterrent within the propellant system before and after curing, explore the diffusion mechanism, and compare the diffusion rates before and after curing. The results indicate that the UV-curable deterrent effectively reduced the concentration of energetic nitro groups (–NO₂) on the propellant surface. When the deterrent concentration was 7%, the nitrogen content on the surface decreased from 13.5 to 12.82%. Confocal laser Raman spectroscopy revealed that the I₁₁₀₃-to-I₁₂₈₅ ratio (I₁₁₀₃/I₁₂₈₅) of the UV-polymer deterrent gradually decreased from 53.09% at 5 μm to 16.48% at 80 μm, establishing a gradient distribution of the deterrent within the propellant. The molecular dynamics simulation results demonstrated that, following UV-induced curing, the deterrent diffusion coefficient decreased from 41.0 × 10⁻¹⁰ and 18.8 × 10⁻¹⁰ to 3.5 × 10⁻¹⁰ m²s⁻¹, indicating that the UV-curable deterrent provides excellent antimigration properties while achieving efficient precursor penetration.