Synthesis and characterization of carboxylated PBAMO copolymers as promising prepolymers for energetic binders.

The carboxylated poly[3,3-bis(3-azidomethyl)oxetane] (PBAMO) copolymers (poly(BAMO-carboxylate)) were synthesized by substitution of poly[3,3-bis(3-chloromethyl)oxetane] (PBCMO) with potassium carboxylate and sodium azide in DMSO. The synthesized compounds were characterized using various analytical techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, inverse-gated decoupling 13C-nuclear magnetic resonance (13C NMR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), calorimetry, friction, and impact sensitivity analysis. These poly(BAMO-carboxylate) compounds have better thermal properties, with lower glass transition temperatures (ranging from -43 °C to -51 °C) than PBAMO (-37 °C) and higher thermal decomposition temperatures (233-237 °C) than PBAMO (211 °C). Moreover, poly(BAMO0.80-octanoate0.20) and poly(BAMO0.78-decanoate0.22) have higher heats of combustion (5226 and 5665 kJ mol-1, respectively) and negative formation enthalpies (-0.17 and -0.55 kJ g-1, respectively), while PBAMO has lower heat of combustion (3125 kJ mol-1) and positive formation enthalpy (0.06 kJ g-1). The poly(BAMO-carboxylate) compounds have higher values (38-50 J) than that of PBAMO (14 J) in the impact sensitivities. This is a valuable study for improving the properties of PBAMO, which is a high energetic polymeric binder but difficult to handle because of its sensitivity. Therefore, poly(BAMO-carboxylate) could be a good candidate as a prepolymer for designing the energetic polymeric binder.

Ecofriendly synthesis and characterization of carboxylated GAP copolymers.

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 13C-nuclear magnetic resonance (13C 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 °C to -55 °C, compared to glycidyl azide polymer (GAP) (-49 °C) and similar first thermal decomposition temperatures (228-230 °C) in comparison to GAP (227 °C), regardless of the introduction of the carboxylate group in GAP. Moreover, poly(GA0.8-butyrate0.2) and poly(GA0.8-decanoate0.2) 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.