Polyimide-g-nylon 6 copolymers were prepared by the polymerization of phenyl 3,5-diaminobenzoate with several diamines and dianhydrides with a one-step method. The polyimides containing pendant ester moieties were then used as activators for the anionic polymerization of molten epsilon-caprolactam. In the graft copolymer syntheses, the phenyl ester groups reacted quickly with caprolactam anions at 120 degrees C to generate N-acyllactam moieties, which activated the anionic polymerization. The thermal stability and chemical resistance were dramatically increased by the incorporation of only 5 wt % polyimide in the graft copolymers. (c) 2005 Wiley Periodicals, Inc.