Preparation of spherical HMX@PDA-based PBX by co-axial droplet microfluidic technology: Enhancing the interfacial effect and safety performance of composite microspheres

Surface engineering plays a crucial role in improving the performance of high energy materials, and polydopamine (PDA) is widely used in the field of energetic materials for surface modification and functionalization. In order to obtain high-quality HMX@PDA-based PBX explosives with high sphericity and a narrow particle size distribution, composite microspheres were prepared using co-axial droplet microfluidic technology. The formation mechanism, thermal behavior, mechanical sensitivity, electrostatic spark sensitivity, compressive strength, and combustion performance of the microspheres were investigated. The results show that PDA can effectively enhance the interfacial interaction between the explosive particles and the binder under the synergistic effect of chemical bonds and the physical "mechanical interlocking" structure. Interface reinforcement causes the thermal decomposition temperature of the sample microspheres to move to a higher temperature, with the sensitivity to impact, friction, and electrostatic sparks (for S-1) increasing by 12.5%, 31.3%, and 81.5% respectively, and the compressive strength also increased by 30.7%, effectively enhancing the safety performance of the microspheres. Therefore, this study provides an effective and universal strategy for preparing high-quality functional explosives, and also provides some reference for the safe use of energetic materials in practical applications.