Pickering emulsion-templated encapsulation of ammonium dinitramide by graphene sheets for hygroscopic inhibition

Abstract

Ammonium dinitramide (ADN) has received great attention as a green oxidizer used in propellants, but its high hygroscopic nature makes it very challenging for practical applications. Herein, we report a facile method to encapsulate ADN by using Pickering emulsion as a soft template, and alkylated graphene oxide nanosheets (AmGO) as particle surfactant. We demonstrate that the encapsulation of ADN aqueous droplets by AmGO nanosheets (ADN@AmGO) can be successfully achieved in a water-in-toluene emulsion, and we studied the influence of factors such as AmGO concentration, and toluene/water ratio on the morphologies of Pickering emulsion. The ADN@AmGO composites were obtained through vacuum assisted solvents extraction, and the compositional and morphological characterizations were performed by using optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), Raman spectra, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Furthermore, the thermal behaviors were examined by differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. We found that ADN encapsulated by 1.0 wt% of AmGO shows more than 60% decrease in water adsorption. Besides, AmGO reveals pronounced catalytic efficiency on the thermal decomposition of ADN. These outstanding properties make ADN@AmGO promising alternative to be used in the fabrication of high energetic, low signature and eco-friendly propellants.