Polyhydroxyamides(PHAs) having dimethylphenoxy and/or alkoxy pendant group were synthesized by condensation polymerization at room temperature for flame retarding applications. The resulting polymer precursors were characterized by FT-IR and 1H-NMR. PHAs were converted to polybenzoxazoles by thermal cyclization reaction. This reaction was highly endothermic and it was studied by TGA and DSC. To observe the cyclization condition of the polymer precursors, they were annealed in a muffle furnace under vacuum at various temperatures for 3 h. The polymer precursor having a dimethylphenoxy pendant group was the only one that was fully cyclized at the lowest temperature, 250 ℃. In case of the polymer having dialkoxy side chains, the polymer with a longer alkoxy chain was fully cyclized at a higher temperature than the polymer with a shorter alkoxy chain. Thus the cyclization reaction can be controlled by the combination of these two pendant groups. By means of wide-angle X-ray diffraction powder patterns, the fully extended alkoxy side chains formed crystalline domains between the layers of the main chains.

디메틸페녹시/알콕시 펜단트 그룹을 갖는 난연 폴리벤즈옥사졸 전구체를 상온축합중합으로 합성하여 FT-IR, NMR 을 사용하여 분석하였다. 합성된 전구체들은 열에 의하여 고리화 반응을 일으켜 안정한 폴리벤즈옥사졸로 전환되었으며, 이때 많은 발열을 동반하였다. 전구체들은 진공상태에서 온도를 달리하여 각각 3 h 동안 열처리한 후 TGA, DSC 분석을 한 결과, 디메틸페녹시 펜단트 그룹만을 갖는 전구체의 경우 가장 낮은 온도인 250 ℃에서 완전히 고리화 되었다. 알콕시 그룹이 긴 경우는 그 길이가 짧은 경우의 전구체 보다 더 높은 온도에서 고리화가 일어 났으며, X-ray 분석 결과, 이는 긴 알콕시 곁 사슬간의 결정화에서 기인되는 것으로 여겨진다.