Change in Morphology of Polyhydroxyamide, Polybenzoxazole and Carbon Particles by Thermal Treatments

Polyhydroxyamide particles consisting of 4,4’-diamino-3,3’-dihydroxybiphenyl and m-phthalyl chloride were prepared by a precipitation polymerization method. The particles were porous spherical particles with an average diameter of ca. 1 μm. And the polyhydroxyamide particles were transformed into polybenzoxazole particles through the ringclosing reactions by the thermal treatment at 360 °C for 3 h. The polybenzoxazole particles were the rugged spherical particles, but remained unchanged in the size. The thermal decoposition temperature at 5wt% loss was estiamted to be 607 °C. Also, the degrees of crystallinity for the polyhydroxyamide and polybenzoxazole particles were high. Further, the polybenzoxazole particles were transformed into carbon particles by the thermal treatment up to 1000 °C. The morphology changed from rugged surface to smooth surface. However, the diameter was almost kept. Thus, the submicron-sized polyhydroxyamide, polybenzoxazole and carbon particles obtained were found to change the morphology and property by thermal treatments.