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Garrett P, Baiz CR. Hidden Beneath the Layers: Extending the Core/Shell Model of Reverse Micelles. J Phys Chem B 2023; 127:9399-9404. [PMID: 37870992 DOI: 10.1021/acs.jpcb.3c04978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Reverse micelles (RMs) provide a unique and highly tunable model system to study water in confined environments. The complex properties of water within RMs arise from the disruption of extended hydrogen bond (H-bond) networks that mediate local and long-range dynamics in bulk aqueous systems. Modulating the water pool size influences its H-bond dynamics, with smaller RMs increasingly restricting the H-bond network rearrangements leading to slower dynamics; however, within small confined systems, the dynamics of the surfactants also influence the water dynamics. Using ultrafast two-dimensional infrared spectroscopy, we investigate the effects of RM size on the surfactant headgroup rotamer populations and picosecond interfacial H-bond dynamics of aerosol-OT surfactants. We find that the increased water penetration accelerates H-bond dynamics, with larger RMs showing faster dynamics. These results imply that the changes in the RM structure alter the physical structure of the RM interface and thus alter the solvation dynamics. The findings in this study can be used for developing models for structure-specific solvation dynamics that account for the surfactant packing and hydration at the interface.
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Affiliation(s)
- Paul Garrett
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, United States
| | - Carlos R Baiz
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, United States
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2
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Garrett P, Shirley JC, Baiz CR. Forced Interactions: Ionic Polymers at Charged Surfactant Interfaces. J Phys Chem B 2023; 127:2829-2836. [PMID: 36926899 DOI: 10.1021/acs.jpcb.2c08636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Characterizing electrostatic interactions at heterogeneous interfaces is critical for developing a fundamental description of the dynamic processes at charged interfaces. Water-in-oil reverse micelles (RMs) offer a high degree of tunability across composition, polarity, and temperature, making them ideal systems for studying interactions at heterogeneous liquid-liquid interfaces. In the present study, we use a combination of ultrafast two-dimensional infrared spectroscopy and molecular dynamics (MD) simulations to determine the picosecond interfacial dynamics in RMs containing binary compositions of sorbitan monostearate and anionic or cationic cosurfactants, which are used to tune the ratio of charged to nonionic surfactants at the interface. The positively charged polyethylenimine (PEI) polymer is encapsulated within the RMs, and the carbonyl stretching mode of sorbitan monostearate reports on the interfacial hydrogen-bond populations and dynamics. The results show that hydrogen-bond populations are altered through the inclusion of both negatively and positively charged cosurfactants. Charged surfactants increase interfacial water penetration into the surfactant layer, and the surface localization of polymers decreases water penetration. Local hydrogen-bond dynamics undergo a slowdown with the inclusion of charged surfactants, and the encapsulation of polymers results in similar effects, irrespective of the charge.
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Affiliation(s)
- Paul Garrett
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Joseph C Shirley
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Carlos R Baiz
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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3
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Ni H. On the hydrophobic hydration, solvation and interface: A thought essay (I). J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Lin L, Liu Z, Premadasa UI, Li T, Ma YZ, Sacci RL, Katsaras J, Hong K, Collier CP, Carrillo JMY, Doughty B. The Unexpected Role of Cations in the Self-Assembly of Positively Charged Amphiphiles at Liquid/Liquid Interfaces. J Phys Chem Lett 2022; 13:10889-10896. [PMID: 36394318 DOI: 10.1021/acs.jpclett.2c02921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Conventional wisdom suggests that cations play a minimal role in the assembly of cationic amphiphiles. Here, we show that at liquid/liquid (L/L) interfaces, specific cation effects can modulate the assemblies of hydrophobic tails in an oil phase despite being attached to cationic headgroups in the aqueous phase. We used oligo-dimethylsiloxane (ODMS) methyl imidazolium amphiphiles to identify these specific interactions at hexadecane/aqueous interfaces. Small cations, such as Li+, bind to the O atoms in the ODMS tail and pin it to the interface, thereby imposing a kinked conformation─as evidenced by vibrational sum frequency generation spectroscopy and molecular dynamics simulations. While larger Cs+ ions more readily partition to the interface, they do not form analogous complexes. Our data not only point to ways for controlling amphiphile structure at L/L interfaces but also suggest a means for the separation of Li+, or related applications, in soft-matter electronics.
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Affiliation(s)
- Lu Lin
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Zening Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Uvinduni I Premadasa
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Tianyu Li
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Ying-Zhong Ma
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Robert L Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - John Katsaras
- Laboratories and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Kunlun Hong
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Jan-Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
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Zuo H, Wang F, Huang Z, Wang Q, Li J, Rozga P. Synergistic effect of electric field and temperature on POSS modified natural ester insulating oil: A molecular dynamics study. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118923] [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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6
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Garrett P, Baiz CR. Dynamic effect of polymers at the surfactant-water interface: an ultrafast study. SOFT MATTER 2022; 18:1793-1800. [PMID: 35170620 DOI: 10.1039/d1sm01651b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Interfaces play a role in controlling the rates and outcomes of chemical processes. Characterizing the interactions at heterogeneous interfaces is critical to developing a comprehensive model of the role of interfaces and confinement in modulating chemical reactions. Reverse micelles are an ideal model system for exploring the effect of encapsulated species on interfacial environments. Here, we use a combination of ultrafast two-dimensional infrared (2D IR) spectroscopy and molecular dynamics (MD) simulations to characterize the picosecond interfacial dynamics in reverse micelles (RMs) containing acrylamide monomers and polyacrylamide polymers within the aqueous phase. The ester carbonyl vibrations of the sorbitan monostearate surfactants are examined to extract interfacial hydrogen-bonding populations and dynamics. Hydrogen bond populations at the ester carbonyl positions remain unchanged with the inclusion of either polymer or monomer species. Hydrogen-bond dynamics are not altered with the addition of monomer but are slowed down twofold in the presence of encapsulated polyacrylamide polymer species as a result of polymer chains partially localizing to the interface. These findings imply that kinetics of reactions that occur at interfaces or in confined environments could be modulated by interfacial localization of the different components.
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Affiliation(s)
- Paul Garrett
- Department of Chemistry, The University of Texas at Austin, Austin, TX, USA.
| | - Carlos R Baiz
- Department of Chemistry, The University of Texas at Austin, Austin, TX, USA.
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Son Y, Kim BH, Choi BK, Luo Z, Kim J, Kim GH, Park SJ, Hyeon T, Mehraeen S, Park J. In Situ Liquid Phase TEM of Nanoparticle Formation and Diffusion in a Phase-Separated Medium. ACS APPLIED MATERIALS & INTERFACES 2022; 14:22810-22817. [PMID: 35129321 DOI: 10.1021/acsami.1c20824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Colloidal nanoparticles are synthesized in a complex reaction mixture that has an inhomogeneous chemical environment induced by local phase separation of the medium. Nanoparticle syntheses based on micelles, emulsions, flow of different fluids, injection of ionic precursors in organic solvents, and mixing the metal organic phase of precursors with an aqueous phase of reducing agents are well established. However, the formation mechanism of nanoparticles in the phase-separated medium is not well understood because of the complexity originating from the presence of phase boundaries as well as nonuniform chemical species, concentrations, and viscosity in different phases. Herein, we investigate the formation mechanism and diffusion of silver nanoparticles in a phase-separated medium by using liquid phase transmission electron microscopy and many-body dissipative particle dynamics simulations. A quantitative analysis of the individual growth trajectories reveals that a large portion of silver nanoparticles nucleate and grow rapidly at the phase boundaries, where metal ion precursors and reducing agents from the two separated phases react to form monomers. The results suggest that the motion of the silver nanoparticles at the interfaces is highly affected by the interaction with polymers and exhibits superdiffusive dynamics because of the polymer relaxation.
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Affiliation(s)
- Youngju Son
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea
| | - Byung Hyo Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Organic Materials and Fiber Engineering, Soongsil University, Seoul 06978, Republic of Korea
| | - Back Kyu Choi
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea
| | - Zhen Luo
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Joodeok Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea
| | - Ga-Hyun Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - So-Jung Park
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea
| | - Shafigh Mehraeen
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Jungwon Park
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Process, Seoul National University, Seoul 08826, Republic of Korea
- Institute of Engineering Research, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea
- Advanced Institutes of Convergence Technology, Seoul National University, 145, Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16229, Republic of Korea
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Dan L, Zhang K, Huang Z, Wang F, Wang Q, Li J. Molecular-level evaluation of ionic transport under external electric fields in biological dielectric liquids. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Baryiames CP, Garrett P, Baiz CR. Bursting the bubble: A molecular understanding of surfactant-water interfaces. J Chem Phys 2021; 154:170901. [PMID: 34241044 DOI: 10.1063/5.0047377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Surfactant science has historically emphasized bulk, thermodynamic measurements to understand the microemulsion properties of greatest industrial significance, such as interfacial tensions, phase behavior, and thermal stability. Recently, interest in the molecular properties of surfactants has grown among the physical chemistry community. This has led to the application of cutting-edge spectroscopic methods and advanced simulations to understand the specific interactions that give rise to the previously studied bulk characteristics. In this Perspective, we catalog key findings that describe the surfactant-oil and surfactant-water interfaces in molecular detail. We emphasize the role of ultrafast spectroscopic methods, including two-dimensional infrared spectroscopy and sum-frequency-generation spectroscopy, in conjunction with molecular dynamics simulations, and the role these techniques have played in advancing our understanding of interfacial properties in surfactant microemulsions.
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Affiliation(s)
- Christopher P Baryiames
- Department of Chemistry, University of Texas at Austin, 105 E 24th St. Stop A5300, Austin, Texas 78712-1224, USA
| | - Paul Garrett
- Department of Chemistry, University of Texas at Austin, 105 E 24th St. Stop A5300, Austin, Texas 78712-1224, USA
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, 105 E 24th St. Stop A5300, Austin, Texas 78712-1224, USA
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von Domaros M, Liu Y, Butman JL, Perlt E, Geiger FM, Tobias DJ. Molecular Orientation at the Squalene/Air Interface from Sum Frequency Generation Spectroscopy and Atomistic Modeling. J Phys Chem B 2021; 125:3932-3941. [DOI: 10.1021/acs.jpcb.0c11158] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael von Domaros
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Yangdongling Liu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Jana L. Butman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Eva Perlt
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Franz M. Geiger
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Douglas J. Tobias
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
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11
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Baryiames CP, Ma E, Baiz CR. Ions Slow Water Dynamics at Nonionic Surfactant Interfaces. J Phys Chem B 2020; 124:11895-11900. [DOI: 10.1021/acs.jpcb.0c09086] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher P. Baryiames
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Emily Ma
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Carlos R. Baiz
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
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