Hyperbranched Poly(N-(2-hydroxypropyl) methacrylamide) via RAFT Self-Condensing Vinyl Polymerization

We report the first synthesis of hyperbranched poly(N-(2-hydroxypropyl) methacrylamide) (HB-PHPMA) using reversible addition–fragmentation chain transfer (RAFT) self-condensing vinyl polymerization (SCVP). The synthesis of these complex, well-defined architectures involved the copolymerization of HPMA with a chain transfer monomer (CTM). The polymerization kinetics, as well as the effects of initiator concentration and the ratio of monomer to CTM were studied. The resulting polymers show high molecular weights and controlled branching frequencies. Due to their inherent amphiphilic nature, these hyperbranched structures self-assemble into aggregates in water. Additionally, we determined the cloud point of the HB-PHPMA to be in the range of sub-ambient temperature to 40 °C. This approach provides access to a new class of thermoresponsive PHPMA polymers with potential to be used in drug delivery and other biological applications