방향족 폴리히드록시아미드의 합성과 열적 고리화 거동(II) -플루오르 치환체의 영향-

Abstract

Polyhydroxyamide (PHA) was synthesized via low-temperature solution polymerization of 3,3'-dihydroxybenzidine with isophthaloyl chloride, and the derivatives of PHA containing fluoro-substituents were investigated for exploring their potential application as new thermally stable polymer material. The structural properties, solubility, and thermal cyclization of the PHA and its derivatives were characterized using FT-IR, DSC, and TGA to derive the relationship between the structure of the PHA derivatives and the thermal properties and cyclization behavior of the polymer. The PHA derivatives containing fluoro-substituents were readily soluble in a variety of solvents without LiCl, whereas the pristine PHA was soluble only in the presence of LiCl. The DSC analyses under isothermal conditions showed that the PHA derivatives exhibited a faster cyclization rate than the pristine PHA at <TEX>$220^{\circ}C$</TEX> and <TEX>$250^{\circ}C$</TEX>. In addition, the DSC and TGA results revealed that the PHA derivatives could be cyclized into the corresponding polybenzoxazoles at lower temperatures than the pristine PHA; this could be attributed to the lower thermal activation energy of the derivatives owing to the introduction of the fluoro-substituents.