Oligopeptide-based amide functional initiators for ATRP

Polymer-peptide conjugates are receiving significant interest. Here, we show that, under the appropriate conditions, a small family of oligopeptide-based initiators can be used successfully to initiate the polymerization of methacrylic monomers by atom transfer radical polymerization (ATRP), generating new examples of such materials. However, the use of the peptidic amide-based initiators results in polymers which have a higher molecular weight than expected and a significantly higher polydispersity than those prepared from ester-based initiators. In many cases significant initiator remains, suggesting that either not all peptides successfully initiate polymerization or that significant termination reactions occur early in the reaction. This low initiator efficiency agrees with other reports for amino acid-based initiators. It therefore appears that such amide-based initiators can be used successfully, but have a significantly lower applicability than the more commonly used ester-based initiators. (C) 2008 Wiley Periodicals, Inc.