Extended Poly(Phenylquinoxalines) Containing Earbonyl and Sulfide Connecting Groups

Abstract

Novel poly(phenylquinoxalines) (PPQs) containing carbonyl and sulfide connecting groups between the aromatic rings were prepared by condensation of various aromatic bis(o-diamines) with novel extended bis(phenyl-1.2-diketones) in m-cresol. An objective of the work was to determine the effect of replacing oxygen by sulfur in extended PPQs. The polymers prepared were soluble in m-cresol, dimethylsulfoxide, N,Ndimethylacetamide, 1-methyl-2-pyrrolidinone and chlorinated hydrocarbon solvents, and had inherent viscosities as high as 1.23 dl g-1. The PPQs exhibited glass transition temperatures ranging from 217 to 245 C and polymer decomposition temperatures (10% weight loss) as measured by thermogravimetric analysis of 526-568 in air and 510-549 CC in helium. A tough transparent yellow fingernail creasable film with a tensile strength of 94.7 MPa, a tensile modulus of 2562 MPa and elongation at break of 6.4% at 25 "C was cast from a chloroform solution of the polymer prepared from 1,3-bis(phenylglyoxalyl-4phenylthio-4'-benzoyl)benzene and 3,3'-diaminobenzidine. Little difference in properties was observed in the PPQs prepared as compared to the PPQs containing carbonyl and ether connecting groups between the aromatic rings, in spite of the difference in the bonding characteristics of carbon to sulfur and to oxygen.