A branched cationic polymer was synthesized by polyaddition of 4-chloromethyl-1,3-dioxolan-2-one and diethylenetriamine in molten salts. The polyaddition proceeded through nucleophilic addition of the primary amino group to the cyclic carbonate structure and quarternization of the secondary amino group with the chloromethyl group. The resulting cationic polymer was a good and recyclable catalyst for the reaction of carbon dioxide and epoxides owing to the ammonium structure. The complexation with DNA was confirmed by dynamic light scattering and zeta potential measurements, and it suggests the potential application as a carrier for drug delivery system. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 47-51, 2012