Ecofriendly synthesis and characterization of carboxylated GAP copolymers

Abstract

Carboxylated GAP copolymers (polyGA-carboxylate) compounds (1-7), were synthesized by the simultaneous substitution reaction with PECH, sodium azide, and sodium carboxylate in DMSO. The synthesized compounds (1-7) were characterized by various analysis tools, such as Fourier transform infrared (FT-IR), inverse gated decoupling C-13-nuclear magnetic resonance (C-13 NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), calorimetry, and friction and impact sensitivity. These poly(GA-carboxylate) compounds (1-7) have better thermal properties owing to their lower glass transition temperatures, from -48 degrees C to -55 degrees C, compared to glycidyl azide polymer (GAP) (-49 degrees C) and similar first thermal decomposition temperatures (228-230 degrees C) in comparison to GAP (227 degrees C), regardless of the introduction of the carboxylate group in GAP. Moreover, poly(GA(0.8)-butyrate(0.2)) and poly(GA(0.8)-decanoate(0.2)) have higher heats of combustion (2331 and 2976 kJ mol(-1)) and negative formation enthalpies (-0.75 and -2.02 kJ g(-1)), while GAP has a lower heat of combustion (2029 kJ mol(-1)) and positive formation enthalpy (1.33 kJ g(-1)). Therefore, poly(GA-carboxylate) could be a good candidate for the polymeric binder in solid propellants.