Simple and low energy consuming synthesis of cyanate ester functional naphthoxazines and their properties

Abstract

Naphthoxazines functionalized with a cyanate ester group are synthesized in high yield under moderate conditions, including room temperature synthesis, compared with general benzoxazine synthesis. Additionally, this synthesis can shorten reaction pathways for another cyanate ester functional benzoxazine whose polymer exhibits higher thermal properties than general polybenzoxazines. Catalytic polymerization evaluated by differential scanning calorimetry (DSC) indicates multiple exotherm maxima, seemingly including cyanate ester trimerization and polymerization of naphthoxazine. The nature of each exotherm is studied by Fourier transform infrared spectroscopy (FT-IR). Furthermore, their observed exothermic temperatures are lower than those of the reported normal benzoxazines, dicyanate ester blends and cyanate ester functional benzoxazines. Thermal properties determined by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), such as the char yield and glass transition temperature, are relatively high compared to those of ordinary polybenzoxazines, and polymerized blends of benzoxazines and dicyanate esters.