Mesoscale Phenomena in Solutions of 3-methylpyridine, Heavey Water, and an Antagonistic Salt

Published

July 16, 2013

Author(s)

Jan Leys, Deepa Subramanian, Eva Rodezno, Boualem Hammouda, Mikhail A. Anisimov

Abstract

We have investigated controversial issues regarding the mesoscale behavior or 3-methylpyridine 93MP), heavy water, and sodium tetraphenylborate (NaBPh₄) solutions by combining results obtained from dynamic light scattering (DLS) and small-angle neutron scattering (SANS). We have addressed three questions: (i) What is the origin of the mesoscale inhomogeneities (order of 100 nm in size) manifested by the "slow mode" in DLS? (ii) Is the periodic structure observed from SANS an inherent property of this system? (iii) What is the universality class of critical behavior in this system? Our results confirm that the "slow mode" observed from DLS experiments corresponds to long-lived, highly stable mesoscale droplets (order of 100 nm in size), which occur only when the solute (3MP) is contaminated by hydrophobic impurities. SANS data confirm the presence of a periodic structure with a periodicity of about 10 nm. This periodic structure cannot be eliminated by nanopore filtration and thus is indeed an inherent solution property. The critical behavior of this system in the range of concentration and temperatures investigated by DLS experiments indicates that the criticality belongs to the universality class of the 3-dimensional Ising model.

Citation

Soft Matter

Volume

9

Pub Type

Journals

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Keywords

Mesoscale phenomena, small-angle neutron scattering, dynamic light scattering

Citation

Leys, J. , Subramanian, D. , Rodezno, E. , Hammouda, B. and Anisimov, M. (2013), Mesoscale Phenomena in Solutions of 3-methylpyridine, Heavey Water, and an Antagonistic Salt, Soft Matter, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=914127 (Accessed October 14, 2025)