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Title: Ion-specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals

Abstract

The impact of pore geometry and functionality on the dynamics of water nanoconfined in porous media are the subject of some debate. Here, we report the synthesis and small-angle X-ray scattering (SAXS) characterization of a series of perdeuterated gemini surfactant lyotropic liquid crystals (LLCs), in which convex, water-filled nanopores of well-defined dimensions are lined with carboxylate functionalities. Quasielastic neutron scattering (QENS) measurements of the translational water dynamics in these dicarboxylate LLC nanopores as functions of the surfactant hydration state and the charge compensating counterion (Na +, K +, NMe 4 +) reveal that the measured dynamics depend primarily on surfactant hydration, with an unexpected counterion dependence that varies with hydration number. We rationalize these trends in terms of a balance between counterion-water attractions and the nanopore volume excluded by the counterions. On the basis of electron density maps derived from SAXS analyses of these LLCs, we directly show that the volume excluded by the counterions depends on both their size and spatial distribution in the water-filled channels. The translational water dynamics in the convex pores of these LLCs are also slower than those reported in the concave pores of AOT reverse micelles, implying that water dynamics also depend on themore » nanopore curvature.« less

Authors:
 [1];  [1];  [2];  [3];  [4];  [1];  [5]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry
  2. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Science Division
  5. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry; Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
Publication Date:
Research Org.:
Univ. of Minnesota, Minneapolis, MN (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); US Dept. of Defense (DOD); National Science Foundation (NSF); National Institutes of Health (NIH)
OSTI Identifier:
1473701
Grant/Contract Number:  
SC0010328; AC02-06CH11357; CHE-9974839; CHE-1048642; DMR-0832760; DMR-1121288; DMR-1420013; S10OD011952
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 122; Journal Issue: 43; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Jackson, Grayson L., Mantha, Sriteja, Kim, Sung A., Diallo, Souleymane O., Herwig, Kenneth W., Yethiraj, Arun, and Mahanthappa, Mahesh K. Ion-specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals. United States: N. p., 2018. Web. doi:10.1021/acs.jpcb.8b05942.
Jackson, Grayson L., Mantha, Sriteja, Kim, Sung A., Diallo, Souleymane O., Herwig, Kenneth W., Yethiraj, Arun, & Mahanthappa, Mahesh K. Ion-specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals. United States. doi:10.1021/acs.jpcb.8b05942.
Jackson, Grayson L., Mantha, Sriteja, Kim, Sung A., Diallo, Souleymane O., Herwig, Kenneth W., Yethiraj, Arun, and Mahanthappa, Mahesh K. Tue . "Ion-specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals". United States. doi:10.1021/acs.jpcb.8b05942. https://www.osti.gov/servlets/purl/1473701.
@article{osti_1473701,
title = {Ion-specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals},
author = {Jackson, Grayson L. and Mantha, Sriteja and Kim, Sung A. and Diallo, Souleymane O. and Herwig, Kenneth W. and Yethiraj, Arun and Mahanthappa, Mahesh K.},
abstractNote = {The impact of pore geometry and functionality on the dynamics of water nanoconfined in porous media are the subject of some debate. Here, we report the synthesis and small-angle X-ray scattering (SAXS) characterization of a series of perdeuterated gemini surfactant lyotropic liquid crystals (LLCs), in which convex, water-filled nanopores of well-defined dimensions are lined with carboxylate functionalities. Quasielastic neutron scattering (QENS) measurements of the translational water dynamics in these dicarboxylate LLC nanopores as functions of the surfactant hydration state and the charge compensating counterion (Na+, K+, NMe4+) reveal that the measured dynamics depend primarily on surfactant hydration, with an unexpected counterion dependence that varies with hydration number. We rationalize these trends in terms of a balance between counterion-water attractions and the nanopore volume excluded by the counterions. On the basis of electron density maps derived from SAXS analyses of these LLCs, we directly show that the volume excluded by the counterions depends on both their size and spatial distribution in the water-filled channels. The translational water dynamics in the convex pores of these LLCs are also slower than those reported in the concave pores of AOT reverse micelles, implying that water dynamics also depend on the nanopore curvature.},
doi = {10.1021/acs.jpcb.8b05942},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = 43,
volume = 122,
place = {United States},
year = {2018},
month = {9}
}

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