Synthesis and Characterization of Azido Esters as Green Energetic Plasticizers

Abstract

Three azido-esters based green energetic plasticizers were synthesized from their chlorides including DEGBAA (diethyleneglycol bis(azidoacetate)), DPGBAA (dipropyleneglycol bis(azidoacetate)) and HETTAA (hexanetriol tris(azidoacetate)). The syntheses were carried out in a two-step process: the first step was esterification of glycol or triol using chloroacetyl chloride, and the second step was substitution of chloracetate with sodium azide that yields corresponding azido derivatives. The parameters of synthesis such as molar ratio of hydroxyl and acyl groups, and amount and type of solvent (dimethyl sulfoxide and dimethyl formamide) were optimized to achieve maximal conversion and purity of the products. The obtained products were characterized by elemental analysis, nuclear magnetic resonance (NMR), and infrared vibrational spectroscopy (IR). Thermal and rheological properties were determined using DSC and Modular Compact Rheometer. Condensed phase heat of formation and several properties important for high-energy materials were predicted from quantum chemical calculations using CBS-4M method. Detonation and combustion performance of energetic compounds were calculated with the thermochemical computer code EXPLO5V06.05. using the predicted heats of formation and experimentally determined densities as input. The energetic and physical properties of the synthesized compounds were compared to the literature data for common plasticizers.