Study on thermal oxidative stabilization reactions of poly(acrylonitrile-co-itaconic acid) copolymers synthesized at different polymerization stages

The structural evolution of poly(acrylonitrile-co-itaconic acid) (PAI) copolymers synthesized at different polymerization stages during thermal oxidative stabilization (TOS) are quantitatively tracked by the attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) technology. The evolution of β-amino nitrile and conjugated nitrile are quantitatively tracked by peak-fitting technique during TOS. A procedure is developed to get the fine information of TOS reactions, especially to value qualitatively the length of cyclic or ladder structures. There is no distinguished difference of structural evolution of PAI copolymers synthesized at different polymerization stages during TOS process. The length of cyclic or ladder structures for all PAI copolymers possesses almost the same values and decreases gradually as the TOS proceeding. The termination of cyclization and the oxidative dehydrogenation become dominant in the late of TOS process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45245.