Study of the Effects of Intramolecular and Intermolecular Hydrogen-Bonding Systems on the Polymerization of Amide-Containing Benzoxazines

Abstract

Pure para and ortho position amide benzoxazines, pHBA-a and oHBA-a, are synthesized. The hydrogen bonding interactions occurring in pHBA-a and oHBA-a are studied by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H NMR) spectroscopy. FT-IR results show that, while pHBA-a presents intermolecular hydrogen bonding interactions, oHBA-a exhibits an intramolecular five-membered-ring hydrogenbonding system between the NH in the amide group and the oxygen in the oxazine ring. Differential scanning calorimetry (DSC) is used to study the thermal properties of the resins and their respective polymers. A deeper understanding of the hydrogen bond interactions in this family of resins is attempted to have better insights on how these systems influence the polymerization behavior not only with respect to the polymerization temperature but also with respect to the propagation step.