Kinetics and mechanism of thermal decomposition reaction of BAMO/GAP tri-block copolymer

Thermogravimetry-infrared spectrum-mass spectrometry(TG-IR-MS) simultaneous techniques was used to study the thermal decomposition mechanism of poly 3, 3-bis(azidomethyl) oxetane/glycidyl azide polymer(PBAMO/GAP) tri-block copolymer. The activation energy E_a and the pre-exponential factor A calculated by Kissinger and Ozawa method are 148.40 kJ/mol and lnA=33.5 s^-1, respectively. The order of the decomposition reaction obtained by Crane's method is n=1. The IR/MS characteristic peaks of gas products of the decomposition were assigned. Results show that the gas products consist of CH₄/CH₃⁺, N₂O, NO₂, N₃/HN₃, HCN⁺, CHO⁺ and NH²⁺. The mechanism of thermal decomposition of the copolymer is consistent with that of common azide compounds. These typical courses could be expressed as follow: nitrene was released after the decomposition of CH₂-N₃, and then rearrangement occurred, imine was released, and then NH₃. But during the decomposition of PBAMO/GAP tri-block copolymer, another routine was observed, which is the release of CH₂-N₃, and then the release of N₃ and HN₃.