3D-printed CL-20-based energetic composites with interpenetrating polymer networks for enhanced mechanical property and microscale detonation performance

This study presents a strategy for developing CL-20 (Hexanitrohexaazaisowurtzita-ne)-based energetic composites with enhanced mechanical properties and intrinsic safety through the synergistic design of PVA (polyvinyl alcohol) /PAA (polyacrylic acid) interpenetrating polymer networks (IPNs) and direct ink writing (DIW) technology. Based on the “hydrogen bond-covalent bond-plasticization” synergistic reinforcement strategy, an IPNs gel system with tunable mechanical properties was developed. After optimizing the polymer ratio (4:3), Crosslinking agent (1 %), and glycerol content (17.5 %), a balance between toughness, ductility, and strength was attained. The DIW-printed structure exhibited excellent molding accuracy and interfacial adhesion (0.924 MPa to aluminum). System characterization demonstrated that the IPN structure achieved uniform CL-20 distribution and controlled porosity, significantly enhancing its mechanical properties, safety, and detonation performance. Its elastic modulus is close to that of engineering plastics(4.504 GPa), the hardness is between soft rubber and hard plastics (0.107 GPa), and the compressive strength is higher than that of typical PBX explosives (15.64 MPa). By using PVA/PAA IPNs, a “topological entanglement-passivation defect” mechanism was established to suppress mechanical sensitivity. Compared to submicron ε-CL-20, the molded sample reduced impact sensitivity by 33.3 % and friction sensitivity by 128.6 %. Additionally, detonation propagation was achieved in a 1.2 × 1.2 mm charge slot within a 90°-160° corner range, with the critical detonation transmission size reaching 0.3 × 0.3 mm and the detonation velocity maintained at 7362 m/s (82.4 % theoretical detonation velocity). This study offers a scalable manufacturing framework for developing energetic devices that combine mechanical properties, intrinsic safety, and adaptability to complex structures.