With the aim to get a clear understanding of this category of polymerizations, the Michael addition polymerizations of trifunctional amines, i.e. 4-aminomethyl piperidine (AMPD), N-methyl ethylenediamine (MEDA), and 1-(2-aminoethyl) piperazine (AEPZ), with an equimolar diacrylamide, N,N'-methylene diacrylamide (MDA), were investigated. Similar to the polymerizations of these amines with an equimolar diacrylate, novel linear poly(amido amine)s containing secondary and tertiary amines in the backbones are obtained from these polymerizations as reflected by C-13 NMR (INVGATE). In situ monitoring the polymerization processes using NMR shows that the reactivity sequence of three types amines in the trifunctional amines is 2 degrees amine (original) > 1 degrees amine >> 2 degrees amine (formed), and the 2 degrees amine (formed) is kept out of the reaction. But these results are different from those reported for the polymerizations of the similar amines with an equimolar divinyl sulfone and some diacrylates. The molecular weights and properties of poly(amindo amine)s obtained were characterized by GPC, DSC and TGA, respectively. (c) 2005 Published by Elsevier Ltd.