Linear pH-sensitive poly(amido amine)s were synthesized via Michael addition polymerization of N-aminoethyl piperazine (AEPZ) or 4-aminomethyl piperidine (AMPD) with 1,12-dodecylene diacrylamide (DDA). Successive Michael addition reaction of acryl-terminated poly(ethylene oxide) (A-PEO) with the secondary amine of linear poly(DDA-AEPZ) that has one secondary amine in every repeating unit afforded PEO-grafted poly(amido amine). Variation of grafting degree could be obtained conveniently via tuning the feed molar ratio of acryl/secondary amine. When this ratio equals to 1.2, all the secondary amines on the backbone of poly(DDA-AEPZ) (or poly(DDA-AMPD)) were consumed and the comb-shaped polymers were formed. The amphiphilic comb-shaped poly(DDA-AEPZ)-g-PEO was molecularly dissolved in water at pH 2.0 (w/v = 0.25%), and micelles were formed when pH value of aqueous solution was adjusted to 6.5. H-1 NMR data verify the formation of micelles due to the disappearance of signals attributed to poly(DDA-AEPZ). The formation of micelles can be confirmed further by TEM photos, they show that all the particles are approximately spherical and their number-average diameter is around 95 nm. (c) 2006 Elsevier Ltd. All rights reserved.