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Probing solubilization sites in block copolymer micelles using fluorescence quenching
journal contributionposted on 28.10.2014 by Andres F. Olea, Patricio Silva, Irma Fuentes, Francisco Martinez, David Worrall
Any type of content formally published in an academic journal, usually following a peer-review process.
The solubilization sites provided by micelles formed by a diblock copolymer with one neutral hydrophobic block, polystyrene, and one charged hydrophilic block, poly(acrylic acid) or poly(methacrylic acid), have been studied by fluorescence quenching of pyrene by polar and nonpolar quenchers. Pyrene solubilized into these micelles is distributed between the inner corona and the micelle core. The fraction of pyrene residing in the inner corona is almost unity for star micelles, where the corona-forming blocks are larger than the core-forming blocks, and around 0.5 for crew-cut micelles where the opposite situation prevails. The kinetics of the quenching process depends on the pyrene location, i.e. is static in the micelle core, and largely dynamic in the inner corona at low quencher concentration. The rate constants for fluorescence quenching by nitromethane are shown to increase with increasing pH.
This work has been supported by FONDECYT grant 1070371 and The Royal Society. I. Fuentes acknowledges a Ph.D. fellowship from CONICYT.