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Octanol‐rich and water‐rich domains in dynamic equilibrium in the pre‐ouzo region of ternary systems containing a hydrotrope
Author(s) -
Diat Olivier,
Klossek Michael L.,
Touraud Didier,
Deme Bruno,
Grillo Isabelle,
Kunz Werner,
Zemb Thomas
Publication year - 2013
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s002188981302606x
Subject(s) - scattering , chemistry , ternary operation , octanol , neutron scattering , small angle neutron scattering , radius , analytical chemistry (journal) , crystallography , thermodynamics , partition coefficient , chromatography , physics , optics , programming language , computer security , computer science
Ternary mixtures of medium‐chain fatty alcohols, water and a hydrotrope (such as ethanol), near the immiscibility gap, make stable single phases at constant temperature. Interestingly, in this `pre‐ouzo region' these single phases consist of two distinct nanoscopic pseudo‐phases, one octanol‐rich and one water‐rich. This domain of composition, which is known to produce strong light scattering and to separate under ultracentrifugation into two phases, has been studied using contrast variation in small‐angle neutron scattering (SANS) combined with small‐ and wide‐angle X‐ray scattering (SWAXS). The existence of fatty alcohol‐rich domains of well defined size of the order of 2 nm radius is proven. The scattering can be approximated by an Ornstein–Zernike function, which is close to the general expression of Choi, Chen, Sottmann & Strey [ Physica B , (1998), 241–243 , 976–978] with vanishing quadratic Porod term. Exploitation of the relative intensities at the vanishing scattering angle in SANS demonstrates that the distribution coefficient of ethanol between the octanol‐rich and the water‐rich domains is close to one. WAXS of the two coexisting pseudo‐phases is compared with the corresponding binary water–ethanol and octanol–ethanol samples.