Experimental and simulation study on hydrogen-bond-induced crystallization of spherical ammonium dinitramide Li Jingjing

The effects of hydrogen bonding between solvents (ethanol, ethanol-acetone and ethanol-ethyl acetate) and ammonium dinitramide (ADN) crystal faces on the morphology of ADN are studied experimentally and by molecular dynamics (MD) simulation. Scanning electron microscopy shows that ADN recrystallized from ethanol, ethanol-acetone and ethanol-ethyl acetate takes the form of a slice, a sheet aggregate and a sphere, respectively. The MD results show that the order of the standard deviation (E dev) of the hydrogen-bonding energy (E b) in the three solvent systems is as follows: ethanol > ethanol-acetone > ethanol-ethyl acetate. The larger the E dev, the larger the difference of each crystal plane size. The radial distribution function reveals that the carbonyl group of ethyl acetate promotes hydrogen-bond formation between O atoms in the nitro groups of ADN and H atoms in ethanol; meanwhile the O atom in the C - O bond of ethyl acetate forms a hydrogen bond with an H atom in ADN. Therefore, the E dev of each crystal face is further lowered, and finally a spherical ADN is obtained.