THERMAL RIGIDIFICATION OF POLYQUINOLINES BY THERMOLYTIC ELIMINATION OF ETHYLENE FROM A 9,10-DIHYDRO-9,10-ETHANOANTHRACENE UNIT

Polyquinolines 7 and 8 containing the 9,10-dihydro-9,10-ethanoanthracene unit as the connecting group between bis(4-phenylquinoline) units were prepared by the condensation of 2,6-diacetyl-9,10-dihydro-9,10-ethanoanthracene (4) with 4,4ʹ-diamino-3,3ʹ-dibenzoyldiphenyl ether (5) and 3,3ʹ-dibenzoyl-benzidine (6), respectively, in the presence of diphenyl phosphate and m-cresol. Both of the polymers were soluble in chloroform and tetrachloroethane, exhibiting Tgs of 270 and 295 °C, respectively. Heating 7 or 8 at 200 °C for 6 h followed by 300 °C for 2 h resulted in the extrusion of ethylene via a retro [4 + 2] reaction to yield polyquinolines 9 and 10, now containing the 2,6-diacetylanthracene connecting group. These thermally stable polymers were insoluble in chloroform and tetrachloroethane, exhibited Tgs at 308 and 360 °C, respectively, and showed increased storage moduli over the uncured samples. © 1990, American Chemical Society. All rights reserved.