The salt curve revisited - Electrostatic charges govern the viscoelastic properties of micellar solutions
July 31-August 4, 2017
In ionic surfactant micelles, interactions among surfactant monomers, their counterion, and additives are fundamental to tune molecular self-assembly and thus the rheological properties (see Figure 1). Here we propose a combination of 1H-NMR, integrated small-angle neutron scattering (SANS) and small-angle X-ray scattering, and rheology to probe the molecular arrangements of the individual molecules within the micelle and the resulting flow properties [1, 2]. Shifts in the 1H-NMR signal show the penetration of counterions and additives into the micellar surfactant structure while SANS and SAXS determine specific intramicellar length scales and intermicellar interactions. SANS signals are sensitive to the contrast between the solvent (deuterium) and the hydrocarbonic tails in the micellar core (hydrogen) and SAXS access the inner structure of the polar shell because the headgroups, counterions, and penetrated salt have higher electron densities compared to the solvent and to the micellar core.
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Peter Fischer, Marianne Liebi, Rosanna Pasquino, Joachim Kohlbrecher, and Viviane Lutz-Bueno, "The salt curve revisited - Electrostatic charges govern the viscoelastic properties of micellar solutions" in "Association in Solution IV", Ulf Olsson, Lund University, Sweden Norman Wagner, University of Delaware, USA Anand Yethiraj, Memorial University of Newfoundland, Canada Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/assoc_solution_iv/48