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Issue 15, 2011
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Structural changes in block copolymer micelles induced by cosolvent mixtures

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Abstract

We investigated the influence of tetrahydrofuran (THF) addition on the structure of poly(1,2-butadiene-b-ethylene oxide) [PB-PEO] micelles in aqueous solution. Our studies showed that while the micelles remained starlike, the micelle core-corona interfacial tension and micelle size decreased upon THF addition. The detailed effects of the reduction in interfacial tension were probed using contrast variations in small angle neutron scattering (SANS) experiments. At low THF contents (high interfacial tensions), the SANS data were fit to a micelle form factor that incorporated a radial density distribution of corona chains to account for the starlike micelle profile. However, at higher THF contents (low interfacial tensions), the presence of free chains in solution affected the scattering at high q and required the implementation of a linear combination of micelle and Gaussian coil form factors. These SANS data fits indicated that the reduction in interfacial tension led to broadening of the core-corona interface, which increased the PB chain solvent accessibility at intermediate THF solvent fractions. We also noted that the micelle cores swelled with increasing THF addition, suggesting that previous assumptions of the micelle core solvent content in cosolvent mixtures may not be accurate. Control over the size, corona thickness, and extent of solvent accessible PB in these micelles can be a powerful tool in the development of targeting delivery vehicles.

Graphical abstract: Structural changes in block copolymer micelles induced by cosolvent mixtures

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Publication details

The article was received on 24 Mar 2011, accepted on 23 May 2011 and first published on 23 Jun 2011


Article type: Paper
DOI: 10.1039/C1SM05506B
Citation: Soft Matter, 2011,7, 7094-7102
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    Structural changes in block copolymer micelles induced by cosolvent mixtures

    E. G. Kelley, T. P. Smart, A. J. Jackson, M. O. Sullivan and T. H. Epps, Soft Matter, 2011, 7, 7094
    DOI: 10.1039/C1SM05506B

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