Nanoconfinement-Induced Phase Segregation of Binary Benzene-Cyclohexane Solutions within a Chemically Inert Matrix

Published

April 12, 2018

Author(s)

Kathryn Krycka, Joseph A. Dura, II Langston, Christopher M. Burba

Abstract

While a clear understanding of the effects of nanoconfinement on phase transitions of single components liquids is emerging, binary solutions hold promise to provide a fertile and detailed arena to probe intermolecular and molecular/surface interactions under nanoconfinement. Herein, the phase segregation of a binary solution comprised of 80% mole fraction benzene and 20% mole fraction cyclohexane solution confined within SiO₂ nanopores was evaluated using small-angle neutron scattering with hydrogen-deuterium contrast matching. While the benzene and cyclohexane are fully miscible at 303 K (30 °C), it is unambiguously demonstrated that they phase segregate by 153 K (-120 °C), which is below the cubic-to-monoclinic phase transition of cyclohexane. Specifically, the cyclohexane and benzene separate into a core/shell structure, with cyclohexane concentrated at the core. Additionally, a pure benzene solution is found to form a frozen core at 153 K with a thin shell of reduced density immediately adjacent to the SiO₂ nanopore wall.

Citation

Journal of Physical Chemistry C

Volume

122

Issue

14

Pub Type

Journals

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Keywords

Nano confinement, nano pores, phase segregation, interface, neutron diffraction, small angle neutron scattering, hydrogen-deuterium contrast

Citation

, K. , , J. , Langston, I. and , C. (2018), Nanoconfinement-Induced Phase Segregation of Binary Benzene-Cyclohexane Solutions within a Chemically Inert Matrix, Journal of Physical Chemistry C, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922061 (Accessed April 25, 2024)