Carboxylic acid- and hydroxy-functionalized alkoxyamine initiators for nitroxide mediated radical polymerization

A carboxylic acid-functionalized alkoxyamine and a primary hydroxy-functionalized alkoxyamine were synthesized and used as initiators in nitroxide mediated radical polymerization. Both initiators were used to polymerize styrene and t-butyl acrylate, resulting in polymers with well controlled molecular weights and low polydispersities (<1.3). Post-polymer coupling of the carboxylic acid and hydroxy end groups to pyrene dyes was used to verify end group fidelity. UV absorption measurements and gel permeation chromatography using dual refractive index and UV detectors was used to confirm that over 90% of these functional endgroups were available for post-polymer modification. Both pre- and post-polymer modification of these alkoxyamine initiators were demonstrated. Poly(dimethylacrylamide) formed using the carboxylic acid-functionalized initiator was covalently linked to lysozyme to form a protein-polymer conjugate.