Construction of core@double-shell structured energetic composites with simultaneously enhanced thermal stability and safety performance

Abstract

The poor thermal stability and high sensitivity severely hinder the practical application of hexanitrohexaazaisowurtzitane (CL-20). Herein, a kind of novel core@double-shell CL-20 based energetic composites were fabricated to address the above issues. The coordination complexes which consist of natural polyphenol tannic acid (TA) and FeIII were chosen to construct the inner shell, while the graphene sheets were used to build the outer shell. The resulting CL-20/TA-FeIII/graphene composites exhibited simultaneously improved thermal stability and safety performance with only 1 wt% double-shell content, which should be ascribed to the intense physical encapsulation effect from inner shell combined with the desensitization effect of carbon nano-materials from outer shell. The phase transition (ε to γ) temperature increased from 173.70 °C of pure CL-20 to 191.87 °C of CL-20/TA-FeIII/graphene composites. Meanwhile, the characteristic drop height (H50) dramatically increased from 14.7 cm of pure CL-20 to 112.8 cm of CL-20/TA-FeIII/graphene composites, indicating much superior safety performance after the construction of the double-shell structure. In general, this work has provided an effective and versatile strategy to conquer the thermal stability and safety issues of CL-20 and contributes to the future application of high energy density energetic materials.