Well-defined end-functionalized polystyrene, poly(alpha-methylstyrene), and polyisoprene with polymerizable aziridine groups were synthesized by the termination reactions of the anionic living polymers of styrene, alpha-methylstyrene, and isoprene with 1-[2(4-chlorobutoxy)ethyl]aziridine in tetrahydrofuran at -78 degrees C. The resulting polymers possessed the predicted molecular weights and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight < 1.1) as well as aziridine terminal moieties. The cationic ring-opening polymerization of the omega-monofunctionalized polystyrene having an aziridinyl group with Et3OBF4 gave the polymacromonomer, whereas the alpha,omega-difunctional polystyrene underwent crosslinking reactions to afford an insoluble gel. Crosslinking products were similarly obtained by the reaction of the alpha,omega-diaziridinyl polystyrene with poly(acrylic acid)-co-poly(butyl acrylate). (c) 2005 Wiley Periodicals, Inc.