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Gale CD, Levinger NE. Predicting the Geometry of Core-Shell Structures: How a Shape Changes with Constant Added Thickness. J Phys Chem B 2024; 128:1317-1324. [PMID: 38288994 DOI: 10.1021/acs.jpcb.3c07652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
The core-shell assembly motif is ubiquitous in chemistry. While the most obvious examples are core/shell-type nanoparticles, many other examples exist. The shape of the core/shell constructs is poorly understood, making it impossible to separate chemical effects from geometric effects. Here, we create a model for the core/shell construct and develop proof for how the eccentricity is expected to change as a function of the shell. We find that the addition of a constant thickness shell always creates a relatively more spherical shape for all shapes covered by our model unless the shape is already spherical or has some underlying radial symmetry. We apply this work to simulated AOT reverse micelles and demonstrate that it is remarkably successful at explaining the observed shapes of the chemical systems. We identify the three specific cases where the model breaks down and how this impacts eccentricity.
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Affiliation(s)
- Christopher D Gale
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Nancy E Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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2
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Volumetric determination of reverse micelle structural properties and the validity of commonplace approximations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Gale CD, Derakhshani-Molayousefi M, Levinger NE. How to Characterize Amorphous Shapes: The Tale of a Reverse Micelle. J Phys Chem B 2022; 126:953-963. [PMID: 35080415 DOI: 10.1021/acs.jpcb.1c09439] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Aerosol-OT reverse micelles represent a chemical construct where surfactant molecules self-assemble to stabilize water nanodroplets 1-10 nm in diameter. Although commonly assumed to adopt a spherical shape, all-atom molecular dynamics simulations and some experimental studies predict a nonspherical shape. If these aggregates are not spherical, then what shape do they take? Because the tools needed to evaluate the shape of something that lacks regular structure, order, or symmetry are not well developed, we present a set of three intuitive metrics─coordinate-pair eccentricity, convexity, and the curvature distribution─that estimate the shape of an amorphous object, and we demonstrate their use on a simulated aerosol-OT reverse micelle. These metrics are all well-established methods and principles in mathematics, and each provides unique information about the shape. Together, these metrics provide intuitive descriptions of amorphous shapes, facilitate ways to quantify those shapes, and follow their changes over time.
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Affiliation(s)
- Christopher D Gale
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | | | - Nancy E Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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Liu D, Du C, Chen Z, Wang X, Shen W. The stability boundaries of droplets of water/AOT/Dynol-604/isooctane mixed microemulsions. J DISPER SCI TECHNOL 2019. [DOI: 10.1080/01932691.2019.1650758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Doudou Liu
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Changfei Du
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Zhiyun Chen
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Xue Wang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Weiguo Shen
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
- Department of Chemistry, Lanzhou University, Lanzhou, China
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Chen Z, Yu S, Liu D, Shi S, Shen W. Solvation Behaviors of Poly(acrylic acid) in Mixed Solvents of 2-Butoxyethanol + Water. J SOLUTION CHEM 2018. [DOI: 10.1007/s10953-018-0809-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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7
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Cantero-López P, Yañez-Osses O, Páez-Meza MS, López JE, Páez-Hernández D, Arratia-Pérez R. Theoretical and experimental approach on the molecular interactions of the DL-Alanine with an electrolytic environment. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.08.067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Volumetric Studies on Aqueous Solutions of Dodecyltrimethylammonium Bromide and 1-Dodecyl-3-methylimidazolium Bromide. J SOLUTION CHEM 2017. [DOI: 10.1007/s10953-017-0686-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Wang X, Chen Z, Shen W. The volumetric properties of water/AOT/isooctane microemulsions with small-size droplets. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.06.076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Yin T, Wang M, Tao X, Shen W. Liquid-Liquid Phase Equilibria and Interactions between Droplets in Water-in-Oil Microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13464-13471. [PMID: 27936772 DOI: 10.1021/acs.langmuir.6b03496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The liquid-liquid phase equilibria of [water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/n-decane] with the molar ratio w0 of water to AOT being 37.9 and [water/AOT/ethoxylated-2,5,8,11-tetramethyl-6-dodecyne-5,8-diol(Dynol-604)/n-decane] with w0 = 37.9 and the mole fraction α of Dynol-604 in the total surfactants being 0.158 were measured in this study. From the data collected in the critical region, the critical exponent β corresponding to the width of the coexistence curve was determined, which showed good agreement with the 3D-Ising value. A thermodynamic approach based on the Carnahan-Starling-van der Waals type equation was proposed to describe the coexistence curves and to deduce the interaction properties between droplets in the microemulsions. The interaction enthalpies were found to be positive for the studied systems, which evidenced that the entropy effect dominated the phase separations as the temperature increased. The addition of Dynol-604 into the (water/AOT/n-decane) microemulsion resulted in the decrease in the critical temperature and the interaction enthalpy. Combining the liquid-liquid equilibrium data for (water/AOT/n-decane) microemulsions with various w0 values determined previously, it was shown that the interaction enthalpy decreased with w0 and tended to change its sign at low w0, which coincided with the results from the isothermal titration calorimetry investigation. All of these behaviors were interpreted by the effects of entropy and enthalpy and their competition, which resulted from the release of solvent molecules entrapped in the interface of microemulsion droplets and were dependent on the rigidity of the surfactant layers and the size of the droplet.
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Affiliation(s)
- Tianxiang Yin
- School of Chemistry and Molecular Engineering, East China University of Science and Technology , Shanghai 200237, China
| | - Mingjie Wang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology , Shanghai 200237, China
| | - Xiaoyi Tao
- School of Chemistry and Molecular Engineering, East China University of Science and Technology , Shanghai 200237, China
| | - Weiguo Shen
- School of Chemistry and Molecular Engineering, East China University of Science and Technology , Shanghai 200237, China
- Department of Chemistry, Lanzhou University , Lanzhou, Gansu 730000, China
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Abstract
Reverse micelles (RMs) made from water and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) are commonly studied experimentally as models of aqueous microenvironments. They are small enough for individual RMs to also be studied by molecular dynamics (MD) simulation, which yields detailed insight into their structure and properties. Although RM size is determined by the water loading ratio (i.e., the molar ratio of water to AOT), experimental measurements of RM size are imprecise and inconsistent, which is problematic when seeking to understand the relationship between water loading ratio and RM size, and when designing models for study by MD simulation. Therefore, a systematic study of RM size was performed by MD simulation with the aims of determining the size of an RM for a given water loading ratio, and of reconciling the results with experimental measurements. Results for a water loading ratio of 7.5 indicate that the interaction energy between AOT anions and other system components is at a minimum when there are 62 AOT anions in each RM. The minimum is due to a combination of attractive and repulsive electrostatic interactions that vary with RM size and the dielectric effect of available water. Overall, the results agree with a detailed analysis of previously published experimental data over a wide range of water loading ratios, and help reconcile seemingly discrepant experimental results. In addition, water loss and gain from an RM is observed and the mechanism of water exchange is outlined. This kind of RM model, which faithfully reproduces experimental results, is essential for reliable insights into the properties of RM-encapsulated materials.
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Affiliation(s)
- Gözde Eskici
- Department of Biochemistry & Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia 19104, United States
| | - Paul H Axelsen
- Departments of Pharmacology, Biochemistry and Biophysics, and Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Lin H, Zhu H, Guo J, Wang N. Interactions between bromophenol blue and cetyl- trimethylammonium bromide in aqueous solutions and microemulsions. J DISPER SCI TECHNOL 2016. [DOI: 10.1080/01932691.2016.1250215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Hong Lin
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
| | - Hongzhe Zhu
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
| | - Juan Guo
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
| | - Nong Wang
- School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou, P. R. China
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Du C, Wu J, Wang X, Zheng P, Shen W. The Thermodynamic Properties of Dynol-604/AOT Mixed Reverse Micelles in Isooctane. J SOLUTION CHEM 2016. [DOI: 10.1007/s10953-016-0485-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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