High molecular weight poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) prepared by mixed solvent polymerization I. effect of monomer feed ratios on polymerization and stabilization

Abstract

In order to improve the pre-oxidation performance and molecular weight of polyacrylonitrile (PAN). In this work, 3-aminocarbonyl-3-butenoic acid methyl ester) (ABM) was used as comonomers to formulate high molecular weight poly(acrylonitrile-co-3-amino-carbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] copolymer by radical polymerization in the mixed solvent of dimethyl sulfoxide/deionized water =60/40 (wt/wt). The highest molecular weight of resultant P(AN-co-ABM) is 4.87 × 105 g/mol, 5 times larger than that prepared by solution polymerization under the same reaction conditions. The monomer reactivity ratios are calculated by Fineman-Ross and Kelen-Tudos methods based on the elemental analysis results. Thermal properties of P(AN-co-ABM) copolymer with different monomer feed ratios were studied by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry in detail. The results show that the stabilization of P(AN-co-ABM) has been significantly improved by ABM, confirmed by the lower initiation temperature and broader exothermic peak in DSC curves, larger extent of stabilization from FTIR and XRD studies, and smaller Ea of cyclization, which is due to the initiation of ABM through ionic mechanism. This study clearly shows that high molecular weight P(AN-co-ABM) copolymer is a better material for carbon fiber precursor.