For the precision synthesis of primary amino functional polymers, cationic polymerization of a phthalimide-containing vinyl ether monomer precursor, 2-vinyloxyethyl phthalimide (PIVE), was examined using a base-assisting initiating system. Living polymerization of PIVE in CH2Cl2 in the presence of 1,4-dioxane as an added base yielded nearly monodispersed polymers (M-w/M-n < 1.1) and higher molecular weight polymers, which have never been obtained using other initiating systems. Furthermore, block copolymers with hydrophobic or hydrophilic groups could be prepared. The deprotection of the pendant phthalimide groups gave well-defined pH-responsive polymers with pendant primary amino groups. Dual-stimuli-responsive block copolymers having a pH-responsive polyamine segment and a thermosensitive segment self-assembled in water in response to both pH and temperature. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48:1207-1213, 2010