Thermal conversion of t-butyloxycarbonyloxy attached polyamides to polybenzoxazoles

A series of t-butyloxycarbonyloxy (t-boc-oxy) attached polyamide (t-bocPA) as a polybenzoxazole (PBO) precursor was synthesized from poly(o-hydroxyamide) (PAOH) and its thermal conversion to PBO was investigated by using FT-IR, TGA and DSC. Most of the protecting group of t-bocPA was decomposed at 250 degrees C and the polymer converted to PBO at 350 degrees C. The thermal reaction for PBO formation was accelerated by the strong acid such as p-toluenesulfonic acid. It was revealed that photo-acid generator (PAG) can act not only as an acid generator on UV exposure, but also as a catalyst to lower the temperature of PBO formation.