RIGID-ROD POLYQUINOLINES: SYNTHESIS, STRUCTURE-PROPERTY RELATIONSHIPS AND HIGH-STRENGTH FIBERS

Synthesis of 3,3'-dibenzoylbenzidine, a monomer needed for the preparation of rigid-rod polyquinolines, was accomplished by a bis(1,5-cyclooctadiene)nickel(0) promoted coupling of 2-amino-5-bromobenzophenone. The synthesis of a diacetyl monomer, p,p'''-diacetylquaterphenyl, was accomplished by the nickel(0) promoted coupling of 4-acetyl-4'-bromobiphenyl.; The Friedlander condensations of 3,3'-dibenzoylbenzidine with a variety of diacetyl and diphenacetyl aromatic compounds were carried out in a m-cresol/di-m-cresyl phosphate medium to afford rigid-rod; ; polyquinolines that had limited solubilities, high Tg's (345-370(DEGREES)C), and the retention of a high percentage of mechanical properties above Tg. The polymers were crystalline and showed crystalline transition temperatures of (GREATERTHEQ) 500(DEGREES)C.; Semirigid polyquinolines were prepared by the polymerizations of 3,3'-dibenzoylbenzidine with 4,4'-diacetyldiphenyl ether or 4,4'-diphenacetyldiphenyl ether. Semirigid-rod polyquinolines containing ether links between the quinoline units were prepared by the condensation of 4,4'-diamino-3,'-dibenzoyldiphenyl ether with p,p''-diacetylterphenyl or p'''-diacetylquaterphenyl. The semirigid polymers had improved solubilities, lower Tg's (260-330(DEGREES)C), and lost a significant percentage of mechanical properties above Tg. None of the semirigid polymers exhibited crystalline transition temperatures.; The semirigid- and rigid-rod polyquinolines exhibited excellent thermal (PDT = 540-600(DEGREES)C) and thermoxidative (PDT = 520-580(DEGREES)C) stabilitiesin nitrogen and air atmospheres. Films of poly{lcub}2,2'-(p,p'-biphenyl)-6,6'-bis(4-phenylquinoline){rcub} showed only a 15% weight loss at 371(DEGREES)C in air after 100 h.; Tough flexible films and fibers of the rigid-rod polymers were obtained directly from the polymerization dopes. Anisotropic solutions (18.5%) of poly{lcub}2,2'-(p,p'-biphenyl)-6,6'-bis(4-phenylquinoline){rcub} in m-cresol/di-m-cresyl phosphate (5:1 molar ratio) were jet-dry wet spun into fibers which, after heat treatment, possessed tenacities and moduli of up to 9.0 and 340 g/d, respectively.