Preparation and some properties of diamine-diacid type alternating copolyamides

The polycondensations of N,N′-bis-(6-aminohexyl)oxamide, N,N′-bis-(6-aminohexyl) succinimide and N,N′-bis(6-aminohexyl)-sebacamide, with p-nitrophenyl adipate in 1,2,4-trichlorobenzene solution, using relatively low temperature (100°) to avoid the amide exchange reactions, gave alternating copolyamides corresponding to (6-6) (6-2), (6-6) (6-4) and (6-6) (6–10) nylons. These copolymers have melting points between those of their corresponding homopolyamides, whereas the random copolymers melt lower than either of the homopolymers. The microstructure of the copolymers seems to be modified by heat treatment below the melting points. Amide exchange reactions occur when they are heated to melting. C¹³ spectra allowed differentiation between the CO groups of the two constituent units of the copolymers, but not between the alternating and the random copolymers.