Novel star-like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3-amino-1,2-propanediol (APD) with feed molar ratio of 1:2. H-1, C-13, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A-MPEO) and carboxylic acid-terminated poly(C-caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core-shell structures with poly(1TT-2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star-like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and H-1 NMR. (C) 2008 Wiley Periodicals, Inc.