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Atomistic structure of a micelle in solution determined by wide Q-range neutron diffraction


Reference:

Hargreaves, R., Bowron, D. T. and Edler, K., 2011. Atomistic structure of a micelle in solution determined by wide Q-range neutron diffraction. Journal of the American Chemical Society, 133 (41), pp. 16524-16536.

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    Official URL:

    http://dx.doi.org/10.1021/ja205804k

    Abstract

    The accepted picture of the structure of a micelle in solution arises from the idea that the surfactant molecules self-assemble into a spherical aggregate, driven by the conflicting affinity of their head and tail groups with the solvent. It is also assumed that the micelle's size and shape can be explained by simple arguments involving volumetric packing parameters and electrostatic interactions. By using wide Q-range neutron diffraction measurements of H/D isotopically substituted solutions of decyltrimethylammonimum bromide (C(10)TAB) surfactants, we are able to determine the complete, atomistic structure of a micelle and its surroundings in solution. The properties of the micelle we extract are in agreement with previous experimental studies. We find that similar to 45 surfactant molecules aggregate to form a spherical micelle with a radius of gyration of 14.2 angstrom and that the larger micelles are more ellipsoidal. The surfactant tail groups are hidden away from the solvent to form a central dry hydrophobic core. This is surrounded by a disordered corona containing the surfactant headgroups, counterions, water, and some alkyl groups from the hydrophobic tails. We find a Stern layer of 0.7 bromide counterion per surfactant molecule, in which the bromide counterions maintain their hydration shells. The atomistic resolution of this technique provides us with unprecedented detail of the physicochemical properties of the micelle in its solvent.

    Details

    Item Type Articles
    CreatorsHargreaves, R., Bowron, D. T. and Edler, K.
    DOI10.1021/ja205804k
    DepartmentsFaculty of Science > Chemistry
    Publisher StatementEdler_JACS_2011_133_41_16524.pdf: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/ja205804k
    RefereedYes
    StatusPublished
    ID Code27284

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