ANIONIC SYNTHESIS AND CHARACTERIZATION OF POLY(STYRENE-BLOCK-ETHYLENE OXIDE) POLYMERS WITH FLUORESCENT-PROBES AT THE BLOCK JUNCTIONS

Fluorescent-labeling reactions of poly(styryl)lithium were effected with either 2-(1-phenylethenyl)naphthalene or 1-phenyl-1-(1-pyrenyl)ethylene followed by functionalization of the resulting 1-phenyl-1-arylalkyllithium species with ethylene oxide. The resulting polymeric alkoxylithiums were used to initiate the anionic polymerization of ethylene oxide in a mixture of benzene and dimethyl sulfoxide. A series of block copolymers [M(n)(PS) = 5.1 x 10(3) g/mol);M(W)/M(n) = 1.02] with 20-40wt% ethylene oxide were characterized by thin-layer chromatography, size exclusion chromatography, H-1 NMR and quantitative UV-visible spectroscopy. Fluorescence measurements on the block copolymers were carried out in 1,2-dichloroethane with varying amounts of methanol. No excimer formation was detected for either naphthalene- or pyrene-labeled block copolymers. Energy transfer from the naphthalene- to the pyrene-labeled polymers was observed at about 80 vol.% methanol. These results are discussed in relationship to the interfacial boundary distances in the block copolymer micelles as deduced by application of the "Spectroscopic Ruler".