A series of soluble aromatic polyamide copolymers were prepared by the one-step polymerization or two-step polymerization of p-phenylene diamine (A2 monomer)

trimesic acid (B3 monomer)

and p-aminobenzoic acid (AB monomer).The structure of resulting polymers was confirmed by IR

1H-

and 13C-NMR measurements.The copolymerization behavior was investigated by IR and 1H-NMR.1H-NMR spectra of the polymers indicated that the AB monomer reacted by inches with the increasing of reaction time.The copolymers synthesized by two-step polymerization had different structures as compared with the one-step copolymer.The influence of three different monomers on the polymerization was investigated.