Computational screening of oxetane monomers for novel hydroxy terminated polyethers.

Abstract

Energetic hydroxy terminated polyether prepolymers find paramount importance in search of energetic binders for propellant applications. In the present study, density functional theory (DFT) has been employed to screen the various novel energetic oxetane derivatives, which usually construct the backbone for these energetic polymers. Molecular structures were investigated at the B3LYP/6-31G* level, and isodesmic reactions were designed for calculating the gas phase heats of formation. The condensed phase heats of formation for designed compounds were calculated by the Politzer approach using heats of sublimation. Among the designed oxetane derivatives, T4 and T5 possess condensed phase heat of formation above 210 kJ mol(-1). The crystal packing density of the designed oxetane derivatives varied from 1.2 to 1.6 g/cm(3). The detonation velocities and pressures were evaluated using the Kamlet-Jacobs equations, utilizing the predicted densities and HOFCond. It was found that most of the designed oxetane derivatives have detonation performance comparable to the monomers of benchmark energetic polymers viz., NIMMO, AMMO, and BAMO. The strain energy (SE) for the oxetane derivatives were calculated using homodesmotic reactions, while intramolecular group interactions were predicted through the disproportionation energies. The concept of chemical hardness is used to analyze the susceptibility of designed compounds to reactivity and chemical transformations. The heats of formation, density, and predicted performance imply that the designed molecules are expected to be candidates for polymer synthesis and potential molecules for energetic binders.