Diblock, Triblock and Cyclic Amphiphilic Copolymers with CO2 Switchability: Effects of Topology.

The combination of topology and CO2 switchability could provide new options for amphiphilic copolymers. Cyclic molecules supply novel topologies, and CO2 switching provides stimulus responsiveness. Cyclic poly(2-(diethylamino)ethyl methacrylate)-b-poly(ethylene oxide) and their corresponding block copolymers were prepared from poly(ethylene oxide) and 2-(diethylamino)ethyl methacrylate via atom transfer radical polymerization and Keck allylation with a Hoveyda-Grubbs catalyst. Changes in conductivity, surface activity, and hydrodynamic size were examined to illustrate the switchability of the produced amphiphilic copolymers upon contact with CO2 in the presence of water. The reversible emulsification and switchable viscosity behaviors of the copolymers were also demonstrated.