Heat Stable Polymers: Polyphenylene and Other Aromatic Polymers.

The Diels-Alder reaction of cyclopentadienones with acetylenic dienophiles provides a unique synthesis of polyphenylenes. High molecular weight 60 - 100,000 phenylated polyphenylenes are amorphous and soluble in common organic solvents. Isomer studies on model compounds indicate that about 50 of the new linkages in the phenylated polyphenylene are meta catenated which may account in part for their good solubility. A new phenylated polyphenylated polyphenylene containing fewer pendant phenyls per repeating unit has been synthesized. Its thermal and solubility properties are similar to previous phenylated polyphenylenes. A new synthetic route to p-bis-2-pyrone has been developed allowing larger quantities of monomer to be prepared. The Diels-Alder reaction of the bis-2-pyrone with p-diethynylbenzene provides an unequivocal synthesis of polyp-phenylene. The model reaction of 3,4-diphenylthiophene dioxide with phenylacetylene demonstrated that this reaction is not a suitable polymer forming reaction since dimerization of the sulfone competes with acetylene addition. Model reactions leading to polyp-phenylene containing removable chromium tricarbonyl arene complexes to improve solubility during polymer formation were studied. Modified author abstract