Synthesis and Modification of Carboxylated Polyphenylenes and Phenylated Polyimides.

Carboxylated and phenylated biscyclopentadienones have been copolymerized with aromatic dialkynes to afford a series of carboxylated phenylated-polyphenylenes. The polyphenylenes were converted to the corresponding potassium, magnesium, and barium salts to afford a series of aromatic ionomers. Thermogravimetric analyses of the barium ionomer show no weight loss until near 500 C. A phenylated biscyclopentadienone containing a pyridine linkage has also been prepared and polymerized with p-diethynylbenzene. Several phenylated polyimides have been prepared by the polymerization of phenylated diahydrides with aromatic diamines. The polyimides are soluble in chloroform and can be cast into thin films that are flexible, slightly yellow, and transparent. Finally, acetylene-terminated polyphenylene oligomers were prepared from a biscyclopentadienone and excess p-diethynylbenzene. These oligomers undergo thermal crosslinking near 250 C without the evolution of volatiles to afford insoluble, thermally-stable resins.