Multilevel core-shell strategies for improving mechanical properties of energetic polymeric composites by the grafting-from route

Weak interfacial interactions always restricted and weakened the properties of the composite materials and constituted a primary bottleneck. Herein, under the guidance of bioinspired engineering thought and inimitable structural features of hyperbranched polymers (HBPs), a series of designed multilevel core-shell 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) particles by in-situ grafting HBPs on polydopamine (PDA) surface via graftingfrom route was reported. Then, using water suspension granulation method, TATB based PBX composites were prepared by adding polymer binder solution dropwise into explosive suspension. The results displayed that a high efficiency mechanical enhancement of polymer bonded explosives (PBX) composites was achieved. After the incorporation of linear soft chains to regulate the outer shell of hyperbranched polyurethane (HBPU), the composites with multilevel core-shell-shell structure revealed the highest tensile and compressive strength at only 1.5 wt% polymer shell content. Based on morphology and structure characterization, contact angle measurement and small-angle neutron scattering (SANS) measurement, a mechanical reinforcement mechanism was proposed. This approach provides a promising project for design and preparation of high performance polymer composites.