Synthesis and characterization of fluorene end-labeled polymers prepared by nitroxide-mediated polymerization

The fluorene-based alkoxyamine 9-(2,2,6,6-tetramethyl-4-hydroxypiperidinyloxy)fluorene was prepared and investigated as a unimolecular initiator in the nitroxide-mediated polymerization (NMP) of styrene. Reactions performed in either bulk or ethereal solvents at 125 °C generated polymers possessing low polydispersity indices (PDIs) and number average molecular weight (Mn) values close to those anticipated based on monomer-to-initiator ratios. A linear relationship between monomer conversion and Mn values was observed by analysis of reaction aliquots with 1H NMR and gel permeation chromatography (GPC), while PDI values remained low throughout. Analysis of the polymers by UV-vis spectroscopy indicated that approximately 80% of the polymer chains were labeled with the fluorene chromophore, while fluorescence spectroscopy was used to verify that the fluorene was polymer-bound.