Hyperbranched Bisphosphonate‐Functional Polymers via Self‐Condensing Vinyl Polymerization and Postpolymerization Multicomponent Reactions

The synthesis of hyperbranched aminobisphosphonic acid polymers via reversible addition‐fragmentation chain transfer (RAFT) self‐condensing vinyl polymerization is reported. A novel acrylamide‐functional chain transfer monomer is synthesized and characterized by 1H and 13C NMR spectroscopy, elemental analysis, and mass spectrometry. The monomer is subsequently copolymerized with an acrylamide monomer bearing a pendent amine group to create hyperbranched amine‐functional polymers with degrees of branching dictated by changing the reaction stoichiometry. The aminobisphosphonate functional group is introduced via a 3‐component Kabachnik‐Fields reaction. An alternate functionalization of the amine polymers to create acid‐degradable imine hydrogels is also employed. This work demonstrates the application of multicomponent reactions to RAFT‐derived hyperbranched polymers and provides a new route to previously inaccessible polymers