SYNTHESIS AND PROCESSING OF POLY(P-PHENYLENE) VIA THE PHOSPHORIC ACID-CATALYZED PYROLYSIS OF A STEREOREGULAR PRECURSOR POLYMER - A CHARACTERIZATION STUDY

Flexible, free-standing films of high molecular weight, structurally r egular poly(p-phenylene) (PPP) were prepared via the thermal conversio n of a stereoregular precursor polymer using o-phosphoric acid as an a romatization catalyst. Approximately 83-90 wt.% of the resulting polym etaphosphoric acid formed during pyrolysis can be removed from the as- synthesized PPP films by washing in dilute aqueous HCl. The small amou nt of residual polymetaphosphoric acid left in the free-standing films acts as a plasticizer by imparting a degree of flexibility to the oth erwise brittle polymer. The resulting PPP films are amorphous by X-ray diffraction. Infrared and W-Vis-NIR analyses of the films are consist ent with high molecular weight, completely 1,4-linked polyphenylene ch ains. The washed PPP films exhibit remarkable thermal and thermal oxid ative stability. They also can be doped by 98% H2SO4 to form air-stabl e conducting complexes that can be subsequently undoped by diluting th e acid with water.