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Shim Y. Computer simulation study of fluorocarbon phosphate surfactant based aqueous reverse micelle in supercritical CO 2: roles of surfactant functional groups, ionic strength, and phase changes in CO 2. Phys Chem Chem Phys 2020; 22:3434-3445. [PMID: 31984986 DOI: 10.1039/c9cp06613f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Structural and dynamic properties of an aqueous micelle organized from fluorocarbon phosphate surfactant molecules in supercritical carbon dioxide (CO2) are investigated via molecular dynamics computer simulations. The roles of the functional groups and ionic strength of the surfactants on the formation of reverse micelles in supercritical CO2, and related water dynamics characterized as translational and reorientational dynamics, are systematically demonstrated by employing three different phosphate-based surfactants paired with sodium cations. The strong electrostatic interactions between the phosphate head groups and sodium cations result in formation of an aqueous core inside the surfactant aggregates, where water molecules are bonded together with loss of the tetrahedral hydrogen bonded network found in bulk water. It is found that all the three surfactants with CO2-philic fluorocarbon double tails build up well-stabilized reverse micelles in supercritical CO2, avoiding direct contacts between CO2 and water molecules. Despite this, the surfactant with a carboxylic ester linkage between the phosphate head and fluorocarbon tail group tends to coordinate water molecules toward sustaining the inter-water hydrogen bonds, indicating better efficiency at covering the aqueous core with hydrophobic groups compared to one without a carboxylic ester group. As for water molecules confined in the reverse micelle, their translational and reorientational motions, and fluctuating dynamics of the inter-water hydrogen bonds, significantly slow down compared to bulk water at ambient temperature. The water dynamics become more restricted with an increase in ionic strength of the anionic surfactant; this is attributed to divalent surfactant heads and sodium cations being more tightly bound together with bonding to water compared to monovalent ones. Lastly, the structural and dynamic changes of the reverse micelle caused by a phase change in CO2 are monitored with gradually decreasing temperature and pressure from the supercritical to gaseous state for CO2. The average reverse micelle structure equilibrated in supercritical CO2 is found to remain stable over a time period of 0.2 ms through a depressurization process to gaseous CO2. We note that the diverse pathways of surfactant self-aggregation in gaseous CO2 could be controlled by the preceding solvation procedure in the supercritical regime which governs the final aggregated structures in gaseous CO2.
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Affiliation(s)
- Youngseon Shim
- CAE Group, Autonomous Material Development Laboratory, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon, Gyeonggi 16678, Korea.
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2
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Applicability of nonionic surfactant alkyl polyglucoside in preparation of liquid CO2 emulsion. J CO2 UTIL 2018. [DOI: 10.1016/j.jcou.2018.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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3
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Zhang C, Li Z, Sun Q, Wang P, Wang S, Liu W. CO2 foam properties and the stabilizing mechanism of sodium bis(2-ethylhexyl)sulfosuccinate and hydrophobic nanoparticle mixtures. SOFT MATTER 2016; 12:946-956. [PMID: 26563818 DOI: 10.1039/c5sm01408e] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work, we have prepared CO2-in-water foam by mixing partially hydrophobic SiO2 nanoparticles and sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and studied its properties. The observation of the appearance of the foam revealed that, with the continuous addition of AOT, the phase behavior of the SiO2 nanoparticle and the AOT mixed system transformed from that of a two-phase system of aggregated nanoparticles into that of a uniform dispersed phase. Both foaming ability and foam stability were optimized when the nanoparticles and the AOT were mixed in a proportion of 1 : 5. On the basis of our findings from measurements of the dispersion properties, including measurements of the adsorption isotherm of the surfactant on the nanoparticles, zeta potentials, interfacial tension and the three-phase contact angle, we concluded that the synergistic interactions between the SiO2 nanoparticles and the AOT led to the adsorption of nanoparticles around the bubble surface and the formation of a spatial network structure of nanoparticles in the film, thereby enhancing the mechanical strength of the bubble and improving the resistance to outside disturbances, deformation and drainage. Laser scanning confocal microscopy (LCSM) analysis of the same foams further confirmed the existence of a "viscoelastic shell" wrapped around and protecting the bubble.
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Affiliation(s)
- Chao Zhang
- College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, Shandong, China.
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James C, Hatzopoulos MH, Yan C, Smith GN, Alexander S, Rogers SE, Eastoe J. Shape transitions in supercritical CO2 microemulsions induced by hydrotropes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:96-102. [PMID: 24364680 DOI: 10.1021/la404144a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The ability to induce morphological transitions in water-in-oil (w/o) and water-in-CO2 (w/c) microemulsions stabilized by a trichain anionic surfactant 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulfonate (TC14) with simple hydrotrope additives has been investigated. High-pressure small-angle neutron scattering (SANS) has revealed the addition of a small mole fraction of hydrotrope can yield a significant elongation in the microemulsion water droplets. For w/o systems, the degree of droplet growth was shown to be dependent on the water content, the hydrotrope mole fraction, and chemical structure, whereas for w/c microemulsions a similar, but less significant, effect was seen. The expected CO2 viscosity increase from such systems has been calculated and compared to related literature using fluorocarbon chain surfactants. This represents the first report of hydrotrope-induced morphology changes in w/c microemulsions and is a significant step forward toward the formation of hydrocarbon worm-like micellar assemblies in this industrially relevant solvent.
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Affiliation(s)
- Craig James
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K
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Sagisaka M, Iwama S, Ono S, Yoshizawa A, Mohamed A, Cummings S, Yan C, James C, Rogers SE, Heenan RK, Eastoe J. Nanostructures in water-in-CO2 microemulsions stabilized by double-chain fluorocarbon solubilizers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:7618-7628. [PMID: 23701401 DOI: 10.1021/la400376g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
High-pressure small-angle neutron scattering (HP-SANS) studies were conducted to investigate nanostructures and interfacial properties of water-in-supercritical CO2 (W/CO2) microemulsions with double-fluorocarbon-tail anionic surfactants, having different fluorocarbon chain lengths and linking groups (glutarate or succinate). At constant pressure and temperature, the microemulsion aqueous cores were found to swell with an increase in water-to-surfactant ratio, W0, until their solubilizing capacities were reached. Surfactants with fluorocarbon chain lengths of n = 4, 6, and 8 formed spherical reversed micelles in supercritical CO2 even at W0 over the solubilizing powers as determined by phase behavior studies, suggesting formation of Winsor-IV W/CO2 microemulsions and then Winsor-II W/CO2 microemulsions. On the other hand, a short C2 chain fluorocarbon surfactant analogue displayed a transition from Winsor-IV microemulsions to lamellar liquid crystals at W0 = 25. Critical packing parameters and aggregation numbers were calculated by using area per headgroup, shell thickness, the core/shell radii determined from SANS data analysis: these parameters were used to help understand differences in aggregation behavior and solubilizing power in CO2. Increasing the microemulsion water loading led the critical packing parameter to decrease to ~1.3 and the aggregation number to increase to >90. Although these parameters were comparable between glutarate and succinate surfactants with the same fluorocarbon chain, decreasing the fluorocarbon chain length n reduced the critical packing parameter. At the same time, reducing chain length to 2 reduced negative interfacial curvature, favoring planar structures, as demonstrated by generation of lamellar liquid crystal phases.
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Affiliation(s)
- Masanobu Sagisaka
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561, Japan.
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Worthen AJ, Bryant SL, Huh C, Johnston KP. Carbon dioxide-in-water foams stabilized with nanoparticles and surfactant acting in synergy. AIChE J 2013. [DOI: 10.1002/aic.14124] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Andrew J. Worthen
- Dept. of Chemical Engineering; The University of Texas at Austin; Austin; TX; 78712
| | - Steven L. Bryant
- Dept. of Petroleum & Geosystems Engineering; The University of Texas at Austin; Austin; TX; 78712
| | - Chun Huh
- Dept. of Petroleum & Geosystems Engineering; The University of Texas at Austin; Austin; TX; 78712
| | - Keith P. Johnston
- Dept. of Chemical Engineering; The University of Texas at Austin; Austin; TX; 78712
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Yu W, Zhou D, Yin JZ, Gao JJ. Selective solubilization of 1,3-propanediol using a water–supercritical CO2 microemulsion with Ls-45 as surfactant. RSC Adv 2013. [DOI: 10.1039/c3ra23429k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Sagisaka M, Iwama S, Hasegawa S, Yoshizawa A, Mohamed A, Cummings S, Rogers SE, Heenan RK, Eastoe J. Super-efficient surfactant for stabilizing water-in-carbon dioxide microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5772-5780. [PMID: 21486003 DOI: 10.1021/la104990c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The fluorinated double-tailed glutarate anionic surfactant, sodium 1,5-bis[(1H,1H,2H,2H-perfluorodecyl)oxy]-1,5-dioxopentane-2-sulfonate (8FG(EO)(2)), was found to stabilize water-in-supercritical CO(2) microemulsions with high water-to-surfactant molar ratios (W(0)). Studies were carried out here to obtain detailed information on the phase stability and nanostructure of the microemulsions by using a high-pressure UV-vis dye probe and small-angle neutron scattering (SANS) measurements. The UV-vis spectra, with methyl orange as a reporter dye, indicated a maximum attainable W(0) of 60 at 45 and 75 °C, and SANS profiles indicated regular droplet swelling with a linear relationship between the water core nanodroplet radius and W(0). This represents the highest water solubilization reported to date for any water-in-CO(2) microemulsion. Further analysis of the SANS data indicated critical packing parameters for 8FG(EO)(2) at the microemulsion interface >1.34, representing approximately 1.1 times the value for common aerosol-OT in water-in-heptane microemulsions under equivalent conditions.
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Affiliation(s)
- Masanobu Sagisaka
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
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Abstract
This article reviews approaches for modification of solvent properties of supercritical carbon dioxide (scCO(2)), with particular reference to self-assembly of oligomeric and polymeric solute additives. Of special interest are viscosity modifiers for scCO(2) based on molecular self-assembly. Background on polymers and surfactants with CO(2)-compatible functionalities is covered, leading on to the attempts made so far to increase the scCO(2) viscosity, which are described in detail. The significance of this field, and the implications a breakthrough could bring environmentally and economically will be addressed.
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Affiliation(s)
- Stephen Cummings
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
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Adkins SS, Chen X, Nguyen QP, Sanders AW, Johnston KP. Effect of branching on the interfacial properties of nonionic hydrocarbon surfactants at the air–water and carbon dioxide–water interfaces. J Colloid Interface Sci 2010; 346:455-63. [DOI: 10.1016/j.jcis.2009.12.059] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 12/23/2009] [Accepted: 12/29/2009] [Indexed: 11/30/2022]
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11
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Fanun M. Microstructure of Mixed Nonionic Surfactants Microemulsions Studied By SAXS and DLS. J DISPER SCI TECHNOL 2009. [DOI: 10.1080/01932690802483817] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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Sagisaka M, Hino M, Oasa J, Yamamoto M, Yoda S, Takebayashi Y, Furuya T, Yoshizawa A, Ochi K, Otake K. Characterization of Water/Supercritical CO2 Microemulsion by UV-visible Spectroscopy and Dynamic Light Scattering. J Oleo Sci 2009; 58:75-83. [DOI: 10.5650/jos.58.75] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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13
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Takebayashi Y, Mashimo Y, Koike D, Yoda S, Furuya T, Sagisaka M, Otake K, Sakai H, Abe M. Fourier Transform Infrared Spectroscopic Study of Water-in-Supercritical CO2 Microemulsion as a Function of Water Content. J Phys Chem B 2008; 112:8943-9. [DOI: 10.1021/jp802578y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshihiro Takebayashi
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Yasuaki Mashimo
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Daisuke Koike
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Satoshi Yoda
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Takeshi Furuya
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Masanobu Sagisaka
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Katsuto Otake
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Hideki Sakai
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
| | - Masahiko Abe
- Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Graduate School of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan, Faculty of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki, Aomori 036-8561, Japan, and Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjyuku-ku, Tokyo 162-8601, Japan
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Kitchens CL, Bossev DP, Roberts CB. Solvent Effects on AOT Reverse Micelles in Liquid and Compressed Alkanes Investigated by Neutron Spin−Echo Spectroscopy. J Phys Chem B 2006; 110:20392-400. [PMID: 17034223 DOI: 10.1021/jp063844z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neutron Spin-Echo (NSE) spectroscopy has been employed to study the interfacial properties of reverse micelles formed with the common surfactant sodium bis-2-ethylhexyl-sulfosuccinate (AOT) in liquid alkane solvents and compressed propane. NSE spectroscopy provides a means to measure small energy transfers for incident neutrons that correspond to thermal fluctuations on the nanosecond time scale and has been applied to the study of colloidal systems. NSE offers the unique ability to perform dynamic measurements of thermally induced shape fluctuation in the AOT surfactant monolayer. This study investigates the effects of the bulk solvent properties, water content, and the addition of octanol cosurfactant on the bending elasticity of AOT reverse micelles and the reverse micelle dynamics. By altering these solvent properties, specific trends in the bending elasticity constant, k, are observed where increasing k corresponds to an increase in micelle rigidity and a decrease in intermicellar exchange rate, k(ex). The observed corresponding trends in k and k(ex) are significant in relating the dynamics of microemulsions and their application as a reaction media. Compressed propane was also examined for the first time with a high-pressure, compressible bulk solvent where variations in temperature and pressure are used to tune the properties of the bulk phase. A decrease in the bending elasticity is observed for the d-propane/AOT/W = 8 reverse micelle system by simultaneously increasing the temperature and pressure, maintaining constant density. With isopycnic conditions, a constant translational diffusion of the reverse micelles through the bulk phase is observed, conforming to the Stokes-Einstein relationship.
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Bharatwaj B, Rocha SRP. Interfacial phenomena at the compressed co2-water interface. BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING 2006. [DOI: 10.1590/s0104-66322006000200004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Meziani MJ, Pathak P, Beacham F, Allard LF, Sun YP. Nanoparticle formation in rapid expansion of water-in-supercritical carbon dioxide microemulsion into liquid solution. J Supercrit Fluids 2005. [DOI: 10.1016/j.supflu.2004.10.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Sirard S, Castellanos H, Green P, Johnston K. Spectroscopic ellipsometry of grafted poly(dimethylsiloxane) brushes in carbon dioxide. J Supercrit Fluids 2004. [DOI: 10.1016/j.supflu.2004.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Dupont A, Eastoe J, Martin L, Steytler DC, Heenan RK, Guittard F, Taffin de Givenchy E. Hybrid fluorocarbon-hydrocarbon CO2-philic surfactants. 2. formation and properties of water-in-CO2 microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:9960-9967. [PMID: 15518481 DOI: 10.1021/la0483820] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Hybrid fluorocarbon-hydrocarbon (F-H) sulfate surfactants are shown to be efficient stabilizers in water-in-CO2 (w/c) microemulsions. The chain structure and F-H ratio affect the regions of P-T phase stability and aggregation structure in these w/c phases. High-pressure near-infrared spectroscopy and small-angle neutron scattering measurements of microemulsified water provide evidence for the stabilization of w/c microemulsion droplets. The relative lengths of the two chains were found to influence the favored aggregation structure: for symmetric chain surfactants (F8H8, F7H7) spherical reverse micelles are present, but for asymmetric chain surfactants (F7H4, F8H4) extended cylinder aggregates form. These changes in aggregation are consistent with different surfactant packing parameters owing to the controlled variations in molecular structure. Furthermore, the general order of w/c phase transition pressures (F8H8 < F7H7 and F8H4 < F7H4) is in line with estimations of surfactant fractional free volume, as proposed by Johnston et al. (J. Phys. Chem. B 2004, 108, 1962-1966). Studies of adsorption at the poly(dimethylsiloxane)-water interface are shown to be valuable for assessing the CO2-philicity of new surfactants. All in all, the symmetric F8H8 and F7H7 analogues are seen to be the most efficient compounds from this class for applications in CO2.
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Affiliation(s)
- Audrey Dupont
- School of Chemistry, University of Bristol, Bristol, BS8 1TS United Kingdom
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19
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Bromberg L, Temchenko M, Moeser GD, Hatton TA. Thermodynamics of temperature-sensitive polyether-modified poly(acrylic acid) microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:5683-92. [PMID: 16459580 DOI: 10.1021/la0359530] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The temperature-induced structural changes and thermodynamics of ionic microgels based on poly(acrylic acid) (PAA) networks bonded with poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) (Pluronic) copolymers have been studied by small-angle neutron scattering (SANS), ultra-small-angle neutron scattering (USANS), differential scanning calorimetry (DSC), and equilibrium swelling techniques. Aggregation within microgels based on PAA and either the hydrophobic Pluronic L92 (average composition, EO8PO52EO8; PPO content, 80%) or the hydrophilic Pluronic F127 (average composition, EO99PO67EO99; PPO content, 30%) was studied and compared to that in the solutions of the parent Pluronic. The neutron scattering results indicate the formation of micelle-like aggregates within the F127-based microgel particles, while the L92-based microgels formed fractal structures of dense nanoparticles. The microgels exhibit thermodynamically favorable volume phase transitions within certain temperature ranges due to reversible aggregation of the PPO chains, which occurs because of hydrophobic associations. The values of the apparent standard enthalpy of aggregation in the microgel suspensions indicate aggregation of hydrophobic clusters that are more hydrophobic than the un-cross-linked PPO chains in the Pluronic. Differences in the PPO content in Pluronics L92 and F127 result in a higher hydrophobicity of the resulting L92-PAA-EGDMAmicrogels and a larger presence of hydrophobic, densely cross-linked clusters that aggregate into supramolecular structures rather than micelle-like aggregates such as those formed in the F127-PAA-EGDMA microgels.
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Affiliation(s)
- Lev Bromberg
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Lim KT, Hwang HS, Ryoo W, Johnston KP. Synthesis of TiO2 nanoparticles utilizing hydrated reverse micelles in CO2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:2466-2471. [PMID: 15835711 DOI: 10.1021/la035646u] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Titanium dioxide nanoparticles were produced by the controlled hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of reverse micelles formed in CO2 with the surfactants ammonium carboxylate perfluoropolyether (PFPECOO-+NH4) (Mw = 587) and poly(dimethyl amino ethyl methacrylate-block-1H,1H,2H,2H-perfluorooctyl methacrylate) (PDMAEMA-b-PFOMA). Based on dynamic light scattering measurements, the amorphous TiO2 particles formed by injection of TTIP are larger than the reverse micelles, indicating surfactant reorganization. The size of the particles and the stability of dispersions in CO2 were affected by the molar ratio of water to surfactant headgroup (w(o)), precursor concentration, and injection rate. The amorphous particle size did not change upon depressurization and redispersion in CO2. PDMAEMA-b-PFOMA provided greater stability against particle aggregation at higher reactant concentration compared with PFPECOO-+NH4. The crystallite size after calcination, which was examined by X-ray diffraction and transmission electron microscopy, increased with w(o).
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Stone MT, Smith, PG, da Rocha SRP, Rossky PJ, Johnston KP. Low Interfacial Free Volume of Stubby Surfactants Stabilizes Water-in-Carbon Dioxide Microemulsions. J Phys Chem B 2004. [DOI: 10.1021/jp036224w] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew T. Stone
- Department of Chemical Engineering and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - P. Griffin Smith,
- Department of Chemical Engineering and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Sandro R. P. da Rocha
- Department of Chemical Engineering and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Peter J. Rossky
- Department of Chemical Engineering and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Keith P. Johnston
- Department of Chemical Engineering and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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22
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Semifluorinated Block Copolymer Surfactants for Water-in-CO2 Microemulsions. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s0167-2991(04)80258-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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23
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Sirard SM, Castellanos HJ, Hwang HS, Lim KT, Johnston KP. Steric Stabilization of Silica Colloids in Supercritical Carbon Dioxide. Ind Eng Chem Res 2003. [DOI: 10.1021/ie030543s] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen M. Sirard
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and Department of Photographic Science and Engineering, Pukyong National University, Pusan 608-739, South Korea
| | - Hector J. Castellanos
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and Department of Photographic Science and Engineering, Pukyong National University, Pusan 608-739, South Korea
| | - Ha S. Hwang
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and Department of Photographic Science and Engineering, Pukyong National University, Pusan 608-739, South Korea
| | - Kwon-Taek Lim
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and Department of Photographic Science and Engineering, Pukyong National University, Pusan 608-739, South Korea
| | - Keith P. Johnston
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, and Department of Photographic Science and Engineering, Pukyong National University, Pusan 608-739, South Korea
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24
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Senapati S, Berkowitz ML. Molecular Dynamics Simulation Studies of Polyether and Perfluoropolyether Surfactant Based Reverse Micelles in Supercritical Carbon Dioxide. J Phys Chem B 2003. [DOI: 10.1021/jp035128s] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sanjib Senapati
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Max L. Berkowitz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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25
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Preparation and properties of semifluorinated block copolymers of 2-(dimethylamino)ethyl methacrylate and fluorooctyl methacrylates. POLYMER 2003. [DOI: 10.1016/s0032-3861(03)00566-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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26
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Keiper JS, Simhan R, DeSimone JM, Wignall GD, Melnichenko YB, Frielinghaus H. New phosphate fluorosurfactants for carbon dioxide. J Am Chem Soc 2002; 124:1834-5. [PMID: 11866579 DOI: 10.1021/ja0122142] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anionic phosphate fluorosurfactants were shown to self-assemble into water-in-carbon dioxide microemulsions. The surfactants, having either two fluorinated chains or one fluorinated chain and one hydrocarbon chain, facilitated significant water uptake in CO2. Small angle neutron scattering (SANS) measurements of surfactant/water/CO2 solutions confirmed the presence of nanometer-scale aggregates, indicative of microemulsion formation.
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Affiliation(s)
- Jason S Keiper
- Forschungszentrum Jülich GmbH, Institut für Festkörperforschung, D-52425 Jülich, Germany
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27
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Psathas PA, Sander EA, Lee MY, Lim KT, Johnston KP. Mapping the Stability and Curvature of Emulsions of H2O and Supercritical CO2with Interfacial Tension Measurements. J DISPER SCI TECHNOL 2002. [DOI: 10.1080/01932690208984190] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Psathas PA, Sander EA, Ryoo W, Mitchell D, Lagow RJ, Lim KT, Johnston KP. Interfacial Studies of the Formation of Microemulsions of Water in Carbon Dioxide with Fluorinated Surfactants. J DISPER SCI TECHNOL 2002. [DOI: 10.1080/01932690208984191] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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29
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Dong X, Erkey C, Dai HJ, Li HC, Cochran HD, Lin JS. Phase Behavior and Micelle Size of an Aqueous Microdispersion in Supercritical CO2 with a Novel Surfactant. Ind Eng Chem Res 2001. [DOI: 10.1021/ie010342t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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