Fabrication and investigation of ignition and combustion characteristics of CL-20/CDs composite energetic micro-units

Introducing “0D” CDs as photosensitizers to enhance the laser responsiveness • Constructing photothermal conversion interface micro-units using hydrogen bonding • CDs regulate the pore size distribution of porous micro-units • Establishment of the ignition-combustion model and mechanistic elucidation Composite energetic micro-units are integrated energetic systems in which synergistic components and structural design enable functional coupling and controllable energy release, offering a crucial assembly strategy for efficient laser ignition of high-energy explosives. A key scientific challenge lies in constructing photosensitive micro-units with stable photothermal conversion interfaces and effective energy transfer pathways. In this work, CL-20 is used as the primary energy releasing component, while carbon dots (CDs) are innovatively introduced as photosensitive materials. Sodium alginate (SA) and polyvinyl alcohol (PVA) form the network framework to construct spherical composite energetic micro-units with a three-dimensional porous architecture. Characterization of chemical composition, morphology, and pore size distribution reveals that CDs induce the formation of intermolecular hydrogen bonds and the rearrangement of the hydrogen-bonding network between SA and PVA, which anchoring the boundaries of the 3D network, suppressing the formation of large pores (>50 μm), and enabling controlled regulation of pore size distribution. Laser ignition tests demonstrate that both ignition threshold and ignition delay decrease with increasing CDs content, reaching minima of 166.66 W·cm −2 and 35.4 ms, respectively, confirming the high photothermal conversion efficiency. Furthermore, increasing CDs content (1–9%) induces a pore-migration effect, where large pores gradually disappear and small pores (<50 μm) become dominant. This small porous structure shortens heat and mass transfer distances during combustion and enhances energy release efficiency. For instance, the combustion duration of sample C 7 (7% CDs) is 3.37 times shorter than that of C 1 (1% CDs). These findings provide valuable guidance and data support for the photosensitized design of composite energetic micro-units and for advancing the understanding of their laser ignition and combustion propagation characteristics in high-energy explosive systems.