This article is focused on the synthesis of a new type of graft PA6, which contained alternating styrene/maleimide copolymer main chains and PA6 grafts, by anionic polymerization. The preprepared styrene/maleimide Copolymers with acylated caprolactam (ACL) pendants were used as macroactivators for the polymerization of molten epsilon-caprolactam (CL). Because of the low activating energy for the initial nucleophilic attack of CL anion on the N-ACL, the polymerization took place in a few minutes. The macro-activators were characterized by H-1-NMR. And the thermal properties, dimensional stability, crystallinity, and solvent resistance ability of the graft PA6 were studied, using DSC, TGA, XRD, water absorption measurement, and solubility experiment. (c) 2008 Wiley Periodicals, Inc.