Interpenetrating Poly(urethane–urea)/Epoxy Networks for Superior Blast Shock Wave Attenuation

Protection against blast shock waves requires materials that combine high strength, high toughness, and efficient energy dissipation under extreme dynamic loading, yet these attributes are intrinsically difficult to achieve simultaneously in conventional polyurea. Herein, we report rigid-flexible interpenetrating polymer networks (IPNs) constructed from a poly(urethane-urea) (PUU) prepolymer and an epoxy resin (EP) prepolymer through a solvent-free, one-pot casting process. The optimized formulation, PUU75EP25, delivers a tensile strength of 60.41 MPa and a toughness of 260.35 MJ m-3 and attenuates 81% of the blast shock wave peak overpressure, ranking among the highest values reported for polymeric materials. Split Hopkinson pressure bar tests at a strain rate of 3200 s-1 reveal that PUU75EP25 combines the highest energy absorption efficiency (η ≈ 0.93) with a stable flow-stress plateau up to a true strain of 0.95, demonstrating efficient energy absorption under blast-relevant dynamic loading. In the Sprague-Dawley (SD) rat model, PUU75EP25 achieved a 100% survival rate (vs. 60% for the unprotected group) and reduced the lung injury area from 85.21% (unprotected group) to 16.71% (vs. 46.22% for poly(urethane-urea) protection). This high attenuation arises from the coupling of microscopic dissipation (sacrificial hydrogen-bond breakage and stress-wave scattering at the microphase-separated interfaces) with a macroscopic large-deformation zone that absorbs the shock energy through stable, failure-free deformation. This work establishes network interpenetration as a simple, scalable design principle for blast-protective polymers.