Preparation of poly(p-phenylenbenzobisoxazole) polymerization by 4, 6-diamino-1, 3-benzenediol/terephthalate (TA salt)

4, 6-diamino-1, 3-benzenediol/terephthalate (TA salt) was prepared from 4, 6-diamino-1, 3-benzenediol and terephthalic acid. Poly(p-phenylenebenzobisoxazole) (PBO) was prepared from TA salt in polyphosphoric acid by a solution polycondensation. Polymerization reaction achieved in a kettle reactor and in the Twin-screw extruder. The obtained produces at each reaction steps was characterized by FT-IR, UV, TG-DTG, and its inherent viscosity is 21.58 dL/g. This method of polymerization can shorten the reaction time and obtain PBO with high molecular weight. The growth process of the molecular weight has been studied and the polymerization mechanism has been discussed. The experimental results indicate that high molecular weight polymer can be prepared by using the method of the complex salt. The polymerization proceeds in the twin-screw extruder to increase the uniformity and the molecular weight of polymer in the late reaction. Liquid crystal phase polymerization is controlled by the pervasion.