Constructing Porous Energetic Spherulites via Solvation‐Growth Coupling for Enhanced Combustion

Abstract

The fabrication of materials with hierarchical structures has garnered great interest, owing to the potential for significantly enhancing their functions. Herein, a strategy of coupling molecular solvation and crystal growth is presented to fabricate porous spherulites of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20), an important energetic material. With the addition of polyvinylpyrrolidone in the antisolvent crystallization, the metastable solvate of CL‐20 is formed and grows spherulitically, and spontaneously desolvates to obtain the porous spherulite when filtration, in which the characteristic peak of the nitro group of CL‐20 shifts detected by the in situ micro‐confocal Raman spectroscopy. The effect of polyvinylpyrrolidone is thought to induce the solvation of CL‐20, confirmed by density functional theory calculations, meanwhile acting on the (020) face of CL‐20 to trigger spherulitic growth, demonstrated through infrared spectroscopy and Rietveld refinement of powder X‐ray diffraction. Moreover, compared to common CL‐20 crystals, porous spherulites exhibit enhanced combustion with increases of 6.24% in peak pressure, 40.21% in pressurization rate, and 9.63% in pressure duration effect, indicating the capability of hierarchical structures to boost the energy release of energetic crystals. This work demonstrates a new route via solvation‐growth coupling to construct hierarchical structures for organic crystals and provides insight into the structure‐property relations for material design.