COMPARED PROPERTIES OF AROMATIC POLYAMIDES CONTAINING SILICON IN THE MAIN-CHAIN

Two series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups have been sy nthesized and their properties have been characterized and compared wi th those of related polymers. These polymers are easily soluble in pol ar amidic solvents such as N-methyl-2-pyrrolidinone and dimethylformam ide, and in tetrahydrofuran, and can be cast into thin, transparent fi lms from solution. The polyamides have weight-and number-average molec ular weights in the range of 10 000-40 000 and 3 000-6 000, respective ly, and polydispersities in the range of 3-10. They show glass transit ion temperatures in the range of 236 degrees C-275 degrees C and decom position temperatures above 400 degrees C. The polymer films have low dielectric constants in the range of 3.26-3.68, and good mechanical pr operties (tensile strength 74-100 MPa, tensile modulus 180-386 MPa), t hus being comparable with other high performance dielectrics.