Traceless Staudinger–Bertozzi Ligation for Postpolymerization Modification

Click chemistry is an integral component of the modern polymer synthesis toolbox. It can be used to create functional materials with precise control over structure. Many click chemistries have been investigated, including azide–alkyne cycloadditions, thiol–ene chemistry, and Staudinger-Bertozzi ligations (SBL). However, traceless Staudinger–Bertozzi ligation, which yields materials free of potentially toxic and reactive phosphorus-containing residues, is virtually unexplored in the polymer materials arena. Herein, we prepare styrene-based polymers with pendant phosphines on each repeating unit capable of undergoing traceless SBL using reversible addition–fragmentation chain-transfer (RAFT) polymerization. These polymers undergo efficient traceless SBL with a variety of azides. Our proof-of-concept study includes the preparation of redox-active, water-solubilizing, and fluorescent polymers as well as styrene-functionalized polymers that cannot be accessed by direct polymerization. Our fluorescent polymers were effective as conjugates for the design of live-cell imaging probes, demonstrating the potential of this class of polymers as a platform for the straightforward synthesis of polymeric cell imaging agents. In conducting this study, we have made a valuable addition to the click chemistry toolbox for polymer synthesis.