Synthesis of pH-responsive polymers with amino groups by living cationic polymerization

Various pH-responsive polymers with amino groups were synthesized via living cationic polymerization of vinyl ethers in the presence of an added base. The synthesis starts with living cationic polymerization of 2-vinyloxyethyl phthalimide (PIVE) in CH₂Cl₂ in the presence of 1,4-dioxane at 0°C. The base-stabilized living system yields nearly monodispersed polymers (M_w/M_n < 1.1), which have never been obtained using other initiating systems. The deprotection of the pendant phthalimide groups gave well-defined pH-responsive polymers with pendant amino groups. In addition, various pH-responsive diblock copolymers and star-shaped polymers were also prepared.