Acceleration and Selective Monomer Addition during Aqueous RAFT Copolymerization of Ionic Monomers at 25 °C

An acceleration effect and selective monomer addition during RAFT copolymerization of the oppositely-charged ionic monomers in dilute aqueous solution at 25 degrees C are reported. The reaction is conducted using a non-ionic water-soluble polymer as a macromolecular chain transfer agent under visible light irradiation. A fast iterative polymerization can be induced, even in dilute solution, by the favorable ionic interactions and in situ self-assembly of zwitterionic growing chains. Selelctive monomer addition is achieved in the statistical copolymerization due to the ion-pairing of the oppositely-charged monomers, such as precisely the same reaction rates at a 1: 1 of monomer ratio, otherwise a faster reaction of the minor monomer component over the major one. These behaviors open up an avenue towards the rapid synthesis of sequence-controlled zwitterionic polyelectrolytes that can satisfy the demands of emerging biological applications.