Fluorene end-labeled polystyrene was prepared by atom transfer radical polymerization with 9-bromofluorene as the initiator. Reactions were carried out in bulk or tetrahydrofuran solutions at temperatures of 80 8C or above. Analysis by gel permeation chromatography indicated that the polymers formed had low polydispersities with molecular weights consistently 2-5 times higher than calculated based on monomer-to-initiator ratios. Coupling of two fluorenyl radicals, formed by activation of the 9-bromofluorene, was found to compete with initiation, leading to the higherthan-expected molecular weight values while giving rise to a fluorene dimer. UV-vis spectrometry indicated near-quantitative fluorene labeling of the polystyrene. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2657-2665, 2005

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This laboratory experiment is designed to allow undergraduate students to gain experience in polymer synthesis and characterization. Polystyrene quantitatively end-labeled with fluorene is produced via atom transfer radical polymerization run under a nitrogen atmosphere, using unpurified reagents and solvents. Molecular weight characterization of the polymers is performed using UV–vis spectroscopy, eliminating the need for specialized equipment such as gel permeation chromatography. Number average molecular weight values are obtained using Beer–Lambert's law, which is used to determine the molarity of fluorene-labeled polymers in THF solutions. These calculated values consistently agreed within 11% of molecular weights obtained using calibrated gel permeation chromatography systems, demonstrating the accuracy of the results. This laboratory exercise is suitable for undergraduate students in an organic or polymer chemistry course and requires no previous experience in polymer synthesis or characterization.

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