Near-infrared laser induced direct ignition of 4,4′,5,5′-tetranitro-1H,1′H-[2,2′-biimidazole]-1,1′-diamine by constructing diverse crystal structures.

• Preparation of diverse DATNBI crystal structures through molecular self-assembly. • Introducing crystal defects to enhance the light absorption performance of DATNBI. • The self-sustaining combustion of DATNBI without photosensitizer under NIR laser is achieved. • The electron-hole recombination in the defect state is induced by laser radiation to enhance photothermal conversion. Although laser ignition is considered to be one of the most promising ways to detonate energetic materials due to its high safety and reliability, it is still a challenge to achieve direct ignition of energetic materials by a laser with low-power and near-infrared (NIR) band. In this paper, a molecular self-assembly strategy based on recrystallization was utilized to prepare 4,4′,5,5′-tetranitro-1H,1′H-[2,2′-biimidazole]-1,1′-diamine (DATNBI) crystals with various micro-nano structures. The characterization results suggest that DATNBI crystals with different degrees of roughness and defects by the induction of solvents and surfactants. The crystal defects can not only bring about the enhancement of light absorption of DATNBI in NIR band, but also advance its thermal decomposition, providing reliable support for direct laser ignition of DATNBI profit from the hot spot ignition theory. Combined with density functional theory, it is speculated that electrons of defect states achieve electron-hole recombination by laser radiation, thereby enhancing photothermal conversion. Compared with raw DATNBI, DATNBI crystals with rough surface and abundant defects can be directly ignited by a NIR laser and exhibits self-sustainable combustion. In summary, a direct NIR laser-ignitable energetic material has been prepared via appropriate crystal structure design. [ABSTRACT FROM AUTHOR]