새로운 polybenzoxazole(PBO) 전구체의 합성 및 특성

Abstract

Aromatic polyhydroxyamides(PHAs) having bulky groups and ether linkages in the polymer main chain were synthesized by solution polycondensation at low tem- perature. This precursor copolymers were studied by FT-IR, ¹H-NMR, DSC, TGA, and X-ray diffractometer. The inherent viscosities of the PHAs measured at 35℃ in DMAc solution were in the range of 0.36-0.61 dL/g. All PHAs were soluble in polar aprotic solvent, but became insoluble in any organic solvents after thermal cyclization reaction. The PHAs were converted to polybenzoxazoles(PBOs) by a thermal cyclization reaction, with heat of endotherm. All the PBOs, except PBO 5 and 6 showed glass-transiti- on(Tg) in the range of 149-217℃. Maximum weight loss temperature of the copolymers and PBOs were recorded in the range of 638℃-707℃ in nitrogen. Maximum weight loss temperature of PHA 5 and PBO 5 were 707℃ and 638℃, respectively, which were the highest temperatures among the corresponding copolymers. Copolymers and PBOs in nitrogen showed high char yields in the range of 54-61%, 63-70% at 900℃ respectively.