Synthesis and thermal decomposition of GAP-Poly(BAMO) copolymer

An energetic copolymer of glycidyl azide polymer (GAP) and poly(bis(azidomethyl)oxetane (Poly(BAMO)) was synthesized using the Borontrifluoride-dimethyl ether complex/diol initiator system. The synthesized copolymer exhibited the characteristics of an energetic thermoplastic elastomer (ETPE). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the thermal decomposition behavior and the results were compared with that of the constituent homopolymers. The main weight loss step in all the polymers coincides with the exothermic dissociation of the azido groups in the side chain. In contrast with the behavior of the homopolymers, the copolymer shows a broad exothermic shoulder peak at 298 °C after the main exothermic decomposition peak at 228 °C. Kinetic analysis was performed by Vyazovkin's model-free method, which suggests that the activation energy of the main decomposition step is around 145 kJ/mol and for the second shoulder it is around 220 kJ/mol. Fourier transform infra red (FTIR) spectra of the degradation residues show that the azido groups in the copolymer decompose in two stages at different temperatures which is responsible for the double decomposition behavior.