Fabrication and characterisation of 2NDPA-loaded poly(lactide-co-glycolide) (PLG) microspheres for explosive safety

We demonstrate the microencapsulation of a double-base (DB) rocket propellant stabiliser, 2-nitrodiphenylamine (2-NDPA), that can potentially increase the shelf life of DB rocket propellants. Poly(lactide-co-glycolide) (PLG) microspheres loaded with 2-NDPA were prepared using the oil-in-water emulsion technique. The microsphere size was found to be inversely related to the mixing rate. It was also found that a higher theoretical loading of 2-NDPA resulted in larger microspheres. In addition, a Rosin Rammler distribution function gave an accurate representation of the microsphere size distribution, and the release rate 2-NDPA from PLG microspheres was found to be size dependent. We show that parameters such as the stirring speed and the percent loading of 2-NDPA can be varied to tailor the release of 2-NDPA from PLG microspheres. In addition, we have shown that temperature has a dramatic effect on the release of 2-NDPA from PLG microcapsules.