Micro-seeding and soft template effects on the control of polymorph and morphology of HMX micro particles in solvent-antisolvent process

Abstract

A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine (HMX) explosive micro-particles by solvent-antisolvent method, to control their polymorphs from dangerous gamma (γ) type to the desired and standard beta (β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly (ethylene glycol)-400 (PEG-400) polymer and coconut fatty acid diethanolamide (lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.

Keywords

• Micro seeding
• Polymorph
• HMX
• Explosive
• Micro-particle
• Solvent-antisolvent process