Structural Evolution of Poly(acrylonitrile-co-itaconic acid) during Thermal Oxidative Stabilization for Carbon Materials

Fourier transform infrared spectroscopy (FT-IR) is employed for the quantitative tracking of the structural evolution of poly(acrylonitrile-co-itaconic acid) (PAI) with different itaconic acid (IA) contents during its thermal oxidative stabilization (TOS). The TOS process includes cyclization, oxidation and tautomerization, as characterized by the evolution of the overlapping peaks of cyclic CC, CN, N–H and CO vibrations in FT-IR. The second derivatives of the spectra facilitate the identification of the position of each contributing structure. The following peak-fitting operations and the determination of the molar absorption coefficients using model compounds allow the quantitative tracking of the extent of the TOS process. PAI containing approximately 3 mol % IA exhibits the most efficient TOS process in terms of cyclization, oxygen uptake and dehydrogenation reactions. A quantitative investigation of the evolution of PAI using FT-IR is an efficient way to determine the optimal structural characteristics of the precursors for carbon materials.