1
|
Dou J, Liu J, Wang Y, Zhi L, Shen J, Wang G. Surface Activity, Wetting, and Aggregation of a Perfluoropolyether Quaternary Ammonium Salt Surfactant with a Hydroxyethyl Group. Molecules 2023; 28:7151. [PMID: 37894630 PMCID: PMC10608880 DOI: 10.3390/molecules28207151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/13/2023] [Accepted: 10/15/2023] [Indexed: 10/29/2023] Open
Abstract
This paper reports the synthesis of a novel quaternary surfactant containing a hydroxyethyl group (PFPE-C) and the surface properties of its aqueous solution (investigated by comparisons with two structurally similar chemicals, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC) and PFPE-A). The minimum surface tension (γCMC) and critical micelle concentration (CMC) of the PFPE-C aqueous solution were 17.35 mN/m and 0.024 mmol/L, respectively. This study confirms that surfactants containing hydroxyethyl groups efficiently reduce the surface tension of aqueous solutions, and fluorocarbon surfactants exhibit better surface activity than ordinary hydrocarbon surfactants with similar structures. The micellization, aggregation, air-water interfacial adsorption, and wettability of PFPE-C aqueous solutions have been systematically investigated. Highly concentrated PFPE-C aqueous solutions exhibit good wettability on PTFE and paraffin films. Moreover, the aggregates of PFPE-C in the aqueous solution were clearly seen as vesicles on Cryo-TEM micrographs. Primary biodegradation results indicate that 19% of PFPC-C can be degraded within one week.
Collapse
Affiliation(s)
- Jiangxun Dou
- School of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China; (J.D.); (J.L.); (L.Z.)
| | - Jiaoyan Liu
- School of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China; (J.D.); (J.L.); (L.Z.)
| | - Yan Wang
- School of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China; (J.D.); (J.L.); (L.Z.)
| | - Lifei Zhi
- School of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China; (J.D.); (J.L.); (L.Z.)
| | - Jixian Shen
- China Research Institute of Daily Chemical Industry, Taiyuan 030001, China;
| | - Guoyong Wang
- School of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China; (J.D.); (J.L.); (L.Z.)
| |
Collapse
|
2
|
Molecular self-assemblies in water and brine and solution properties for a hybrid fluorocarbon surfactant. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
3
|
Zhang Y, Li J, Yin Z, Zhang J, Guo W, Wang M. Quantum Chemical Study of the Carbon Dioxide-Philicity of Surfactants: Effects of Tail Functionalization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15352-15361. [PMID: 33300802 DOI: 10.1021/acs.langmuir.0c02789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Carbon dioxide (CO2)-philic surfactants have broad application prospects in organic synthesis, fracture-enhanced oil recovery, polymerization, extraction, and other fields and can be used to enhance the viscosity of supercritical CO2 (scCO2). In this work, the relationship between the functional group of the surfactant tail and CO2-philicity is studied from a new perspective using density functional theory. Three common functional group types (fluorinated, oxidative, and methyl groups) were investigated. The analysis of binding energy demonstrates that all three types of functional groups can improve the CO2-philicity of the surfactant. Among these three kinds of functional groups, the strongest interaction with CO2 molecules is observed for oxidative functional groups followed by semifluorinated, fluorinated, and methyl groups. However, the CO2 molecules tend to be adsorbed onto the middle segment of the oxidative group, and the intrusion of the CO2 molecules results in the low solubility of oxidative surfactants. In contrast, fluorinated and methyl groups interact with CO2 at the end of the surfactant tail. As a result, the fluorinated surfactants show the best solubility in CO2. Therefore, the solubility of a surfactant in CO2 is not only related to the interaction strength between the surfactant and CO2, it also depends on the interaction structure. The results of this study provide a new strategy for evaluating surfactant CO2-philicity and provide guidance for the design of surfactants with high solubility in scCO2.
Collapse
Affiliation(s)
- Yingnan Zhang
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Jiawei Li
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Zhipeng Yin
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Jun Zhang
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Wenyue Guo
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Muhan Wang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266000, China
| |
Collapse
|
4
|
Peng YY, Liao YF, Gan W, Tong QX, Yuan QH. Hydroxyl group modifies aggregation behavior of a non-ionic hydro-fluorocarbon hybrid surfactant by disrupting interfacial water. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2006092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ying-ying Peng
- Flexible Printed Electronics Technology Center, and School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
- Department of Chemistry, and Key Laboratory for Preparation and Application of Ordered Structural Material of Guangdong Province, Shantou University, Shantou 515063, China
| | - Yi-fan Liao
- Department of Chemistry, and Key Laboratory for Preparation and Application of Ordered Structural Material of Guangdong Province, Shantou University, Shantou 515063, China
| | - Wei Gan
- Flexible Printed Electronics Technology Center, and School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Qing-xiao Tong
- State Key Laboratory of Advanced Welding and Joining, and School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Qun-hui Yuan
- State Key Laboratory of Advanced Welding and Joining, and School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| |
Collapse
|
5
|
Sagisaka M, Ono S, James C, Yoshizawa A, Mohamed A, Guittard F, Enick RM, Rogers SE, Czajka A, Hill C, Eastoe J. Anisotropic reversed micelles with fluorocarbon-hydrocarbon hybrid surfactants in supercritical CO 2. Colloids Surf B Biointerfaces 2018; 168:201-210. [PMID: 29276082 DOI: 10.1016/j.colsurfb.2017.12.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/28/2017] [Accepted: 12/09/2017] [Indexed: 11/19/2022]
Abstract
Previous work (M. Sagisaka, et al. Langmuir 31 (2015) 7479-7487), showed the most effective fluorocarbon (FC) and hydrocarbon (HC) chain lengths in the hybrid surfactants FCm-HCn (sodium 1-oxo-1-[4-(perfluoroalkyl)phenyl]alkane-2-sulfonates, where m = FC length and n = HC length) were m and n = 6 and 4 for water solubilization, whereas m 6 and n 6, or m 6 and n 5, were optimal chain lengths for reversed micelle elongation in supercritical CO2. To clarify why this difference of only a few methylene chain units is so effective at tuning the solubilizing power and reversed micelle morphology, nanostructures of water-in-CO2 (W/CO2) microemulsions were investigated by high-pressure small-angle neutron scattering (SANS) measurements at different water-to-surfactant molar ratios (W0) and surfactant concentrations. By modelling SANS profiles with cylindrical and ellipsoidal form factors, the FC6-HCn/W/CO2 microemulsions were found to increase in size with increasing W0 and surfactant concentration. Ellipsoidal cross-sectional radii of the FC6-HC4/W/CO2 microemulsion droplets increased linearly with W0, and finally reached ∼39 Å and ∼78 Å at W0 = 85 (close to the upper limit of solubilizing power). These systems appear to be the largest W/CO2 microemulsion droplets ever reported. The aqueous domains of FC6-HC6 rod-like reversed micelles increased in size by 3.5 times on increasing surfactant concentration from 35 mM to 50 mM: at 35 mM, FC6-HC5 formed rod-like reversed micelles 5.3 times larger than FC6-HC6. Interestingly, these results suggest that hybrid HC-chains partition into the microemulsion aqueous cores with the sulfonate headgroups, or at the W/CO2 interfaces, and so play important roles for tuning the W/CO2 interfacial curvature. The super-efficient W/CO2-type solubilizer FC6-HC4, and the rod-like reversed micelle forming surfactant FC6-HC5, represent the most successful cases of low fluorine content additives. These surfactants facilitate VOC-free, effective and energy-saving CO2 solvent systems for applications such as extraction, dyeing, dry cleaning, metal-plating, enhanced oil recovery and organic/inorganic or nanomaterial synthesis.
Collapse
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.
| | - Shinji Ono
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Craig James
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Atsushi Yoshizawa
- Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Azmi Mohamed
- Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia; Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia
| | | | - Robert M Enick
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, 940 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, United States
| | - Sarah E Rogers
- ISIS-CCLRC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, UK
| | - Adam Czajka
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Christopher Hill
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Julian Eastoe
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
| |
Collapse
|
6
|
Wang M, Wang J, Fang T, Yan Y, Wang Z, Zhang J. Shape transition of water-in-CO2 reverse micelles controlled by the surfactant midpiece. Phys Chem Chem Phys 2018; 20:15535-15542. [DOI: 10.1039/c8cp01844h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Designing CO2-philic surfactants for generating wormlike reverse micelles (RMs) is an effective approach to enhance the viscosity of supercritical CO2 (scCO2), however this remains challenging.
Collapse
Affiliation(s)
- Muhan Wang
- College of Science, China University of Petroleum
- 266580 Qingdao
- China
| | - Junfeng Wang
- College of Science, China University of Petroleum
- 266580 Qingdao
- China
| | - Timing Fang
- College of Science, China University of Petroleum
- 266580 Qingdao
- China
| | - Youguo Yan
- College of Science, China University of Petroleum
- 266580 Qingdao
- China
| | - Zhiyuan Wang
- School of Petroleum Engineering
- China University of Petroleum
- 266580 Qingdao
- China
| | - Jun Zhang
- College of Science, China University of Petroleum
- 266580 Qingdao
- China
| |
Collapse
|
7
|
Wang M, Fang T, Wang P, Yan Y, Zhang J, Liu B, Sun X. Molecular-Scale Design of Hydrocarbon Surfactant Self-Assembly in Supercritical CO 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5291-5297. [PMID: 28485950 DOI: 10.1021/acs.langmuir.7b01176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Forming wormlike reverse micelles (RMs) by hydrocarbon surfactant self-assembly is an economic and environmental strategy to improve the physicochemical properties of supercritical carbon dioxide (scCO2), but it remains challenging. Introducing cosurfactant in hydrocarbon surfactant self-assembly system is a potential method to generate wormlike RMs. Here, adopting molecular dynamics simulations, we performed hydrocarbon surfactant (TC14) self-assembly with introducing cosurfactants (C8Benz). It is found that adding the C8Benz molecules will induce the spherical RMs to a short rodlike form. In this case, the microstructure of the short rodlike RMs shows a dumbbell-like form that is composed by three parts including a middle part of C8Benz and two parts of TC14 aggregation at both ends of rodlike RMs, which is regarded as the origin of RMs shape transition. Further, the analysis of free energy for RMs fusion indicates that the high fusion ability of C8Benz aggregation drives the formation of the dumbbell-like RMs. Accordingly, enhancing the affinity of the C8Benz is found to be effective strategy to further fusion of rodlike RMs in end-to-end manner, yielding a wormlike RMs with a beads-on-a-string structure. It is expected that this work will provide a valuable information for design the hydrocarbon wormlike RMs and facilitate the potential application of scCO2.
Collapse
Affiliation(s)
- Muhan Wang
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Timing Fang
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Pan Wang
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Youguo Yan
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Jun Zhang
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Bing Liu
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| | - Xiaoli Sun
- College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China
| |
Collapse
|
8
|
Wang M, Fang T, Wang P, Tang X, Sun B, Zhang J, Liu B. The self-assembly structure and the CO 2-philicity of a hybrid surfactant in supercritical CO 2: effects of hydrocarbon chain length. SOFT MATTER 2016; 12:8177-8185. [PMID: 27714309 DOI: 10.1039/c6sm01584k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hybrid surfactants containing both fluorocarbon (FC) and hydrocarbon (HC) chains, as effective CO2-philic surfactants, could improve the solubility of polar substances in supercritical CO2. Varying the length of the HC of hybrid surfactants is an effective way to improve the CO2-philicity. In this paper, we have investigated the effects of the HC length on the self-assembly process and the CO2-philicity of hybrid surfactants (F7Hn, n = 1, 4, 7 and 10) in water/CO2 mixtures using molecular dynamics simulations. It is found that the self-assembly time of F7Hn exhibits a maximum when the length of the HC is equal to that of the FC (F7H7). In this case, the investigation of H-bonds between the water core and CO2 phase shows that F7H7 has the strongest CO2-philicity because it has the best ability to separate water and CO2. To explain the origin of the differences in separation ability, the analysis of the structures of the reverse micelles shows that there are two competing mechanisms with a shortening HC. Firstly, the volume of F7Hn is reduced, which thus decreases the separation ability. Moreover, this also leads to the curved conformation of the FC. As a result, the separation ability is enhanced. These two mechanisms are balanced in F7H7, which has the best ability to separate water and CO2. Our simulation results demonstrate that the increased volume and the curved conformation of the hybrid surfactant tail could enhance the CO2-philicity in F7Hn surfactants. It is expected that this work will provide valuable information for the design of CO2-philic surfactants.
Collapse
Affiliation(s)
- Muhan Wang
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China.
| | - Timing Fang
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China.
| | - Pan Wang
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China.
| | - Xinpeng Tang
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China.
| | - Baojiang Sun
- School of Petroleum Engineering, China University of Petroleum, 266580 Qingdao, Shandong, China
| | - Jun Zhang
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China. and Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum, 266580 Qingdao, Shandong, China
| | - Bing Liu
- College of Science, China University of Petroleum, 266580 Qingdao, Shandong, China.
| |
Collapse
|
9
|
Sagisaka M, Ono S, James C, Yoshizawa A, Mohamed A, Guittard F, Rogers SE, Heenan RK, Yan C, Eastoe J. Effect of Fluorocarbon and Hydrocarbon Chain Lengths in Hybrid Surfactants for Supercritical CO2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7479-87. [PMID: 26080002 DOI: 10.1021/acs.langmuir.5b01737] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Hybrid surfactants containing both fluorocarbon (FC) and hydrocarbon (HC) chains have recently been shown to solubilize water and form elongated reversed micelles in supercritical CO2. To clarify the most effective FC and HC chain lengths, the aggregation behavior and interfacial properties of hybrid surfactants FCm-HCn (FC length m/HC length n = 4/2, 4/4, 6/2, 6/4, 6/5, 6/6, and 6/8) were examined in W/CO2 mixtures as functions of pressure, temperature, and water-to-surfactant molar ratio (W0). The solubilizing power of hybrid surfactants for W/CO2 microemulsions was strongly affected by not only the FC length but also by that of the HC. Although the surfactants having short FC and/or HC tails (namely, m/n = 4/2, 4/4, and 6/2) did not dissolve in supercritical CO2 (even at ∼17 mM, ≤400 bar, temperature ≤ 75 °C, and W0 = 0-40), the other hybrid surfactants were able to yield transparent single-phase W/CO2 mixtures identified as microemulsions. The solubilizing power of FC6-HCm surfactants reached a maximum (W0 ∼ 80 at 45 °C and 350 bar) with a hydrocarbon length, m, of 4. The W0 value of 80 is the highest for a HC-FC hybrid surfactant, matching the highest value reported for a FC surfactant which contained more FC groups. High-pressure small-angle neutron scattering measurements from FCm-HCn/D2O/CO2 microemulsions were consistent with growth of the microemulsion droplets with increasing W0. In addition, not only spherical reversed micelles but also nonspherical assemblies (rodlike or ellipsoidal) were found for the systems with FC6-HCn (n = 4-6). At fixed surfactant concentration and W0 (17 mM and W0 = 20), the longest reversed micelles were obtained for FC6-HC6 where a mean aspect ratio of 6.3 was calculated for the aqueous cores.
Collapse
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
| | - Shinji Ono
- †Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Craig James
- †Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Atsushi Yoshizawa
- †Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | | | - Frédéric Guittard
- ∥Univ. Nice Sophia-Antipolis, CNRS, Equipe Surfaces et Interfaces, Parc Valrose, 06100 Nice, France
| | - Sarah E Rogers
- ⊥ISIS-CCLRC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom
| | - Richard K Heenan
- ⊥ISIS-CCLRC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom
| | - Ci Yan
- #School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Julian Eastoe
- #School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| |
Collapse
|
10
|
Bardhan S, Kundu K, Chakraborty G, Saha SK, Paul BK. The Schulman Method of Cosurfactant Titration of the Oil/Water Interface (Dilution Method): A Review on a Well-Known Powerful Technique in Interfacial Science for Characterization of Water-in-Oil Microemulsions. J SURFACTANTS DETERG 2015. [DOI: 10.1007/s11743-015-1694-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
11
|
Investigation of mixed fluorinated and triblock copolymer liquid crystals: Imprint for mesostructured bimodal silica. J Colloid Interface Sci 2015; 446:170-6. [DOI: 10.1016/j.jcis.2015.01.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/14/2015] [Accepted: 01/14/2015] [Indexed: 11/17/2022]
|
12
|
Economical and Efficient Hybrid Surfactant with Low Fluorine Content for the Stabilisation of Water-in-CO2 Microemulsions. J Supercrit Fluids 2015. [DOI: 10.1016/j.supflu.2015.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
13
|
Sagir M, Tan IM, Mushtaq M, Nadeem M. CO2Mobility and CO2/Brine Interfacial Tension Reduction by Using a New Surfactant for EOR Applications. J DISPER SCI TECHNOL 2014. [DOI: 10.1080/01932691.2013.859087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
14
|
Ren G, Sanders AW, Nguyen QP. New method for the determination of surfactant solubility and partitioning between CO2 and brine. J Supercrit Fluids 2014. [DOI: 10.1016/j.supflu.2014.04.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
15
|
Sagir M, Tan IM, Mushtaq M, Ismail L, Nadeem M, Azam MR, Hashmet MR. Novel Surfactant for the Reduction of CO2/Brine Interfacial Tension. J DISPER SCI TECHNOL 2014. [DOI: 10.1080/01932691.2013.794111] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
16
|
Kundu K, Guin G, Paul BK. Interfacial composition, thermodynamic properties, and structural parameters of water-in-oil microemulsions stabilized by 1-pentanol and mixed surfactants. J Colloid Interface Sci 2012; 385:96-110. [DOI: 10.1016/j.jcis.2012.06.057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/28/2022]
|
17
|
Interfacial composition, thermodynamic properties and structural parameters of water-in-oil microemulsions stabilized by 1-pentanol and mixed anionic + polyoxyethylene type nonionic surfactants. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2763-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
18
|
Mohamed A, Sagisaka M, Hollamby M, Rogers SE, Heenan RK, Dyer R, Eastoe J. Hybrid CO2-philic surfactants with low fluorine content. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:6299-6306. [PMID: 22455477 DOI: 10.1021/la3005322] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The relationships between molecular architecture, aggregation, and interfacial activity of a new class of CO(2)-philic hybrid surfactants are investigated. The new hybrid surfactant CF2/AOT4 [sodium (4H,4H,5H,5H,5H-pentafluoropentyl-3,5,5-trimethyl-1-hexyl)-2-sulfosuccinate] was synthesized, having one hydrocarbon chain and one separate fluorocarbon chain. This hybrid H-F chain structure strikes a fine balance of properties, on one hand minimizing the fluorine content, while on the other maintaining a sufficient level of CO(2)-philicity. The surfactant has been investigated by a range of techniques including high-pressure phase behavior, UV-visible spectroscopy, small-angle neutron scattering (SANS), and air-water (a/w) surface tension measurements. The results advance the understanding of structure-function relationships for generating CO(2)-philic surfactants and are therefore beneficial for expanding applications of CO(2) to realize its potential using the most economic and efficient surfactants.
Collapse
Affiliation(s)
- Azmi Mohamed
- School of ChemistryUniversity of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
A semi-fluorinated hybrid amphiphile, pentadecafluoro-5-dodecyl (F7H4) sulfate, has been shown to form reversed micelles in dense CO(2); the aggregates evolve to form water-in-CO(2) (w/c) microemulsion droplets on addition of water. Aggregation structures in these w/c phases have been characterised by small-angle neutron scattering (SANS), showing the presence of cylindrical droplets, which change into dispersed lamellar phases at even higher water loadings. Other systems are also introduced, being high internal phase emulsions (HIPEs) with brine, and liquid and supercritical CO(2), stabilized by certain commercially available nonylphenol ethoxylates (Dow Tergitol NP-, and Huntsman Surfonic N- amphiphiles). These dispersions have been characterised by SANS for the first time. Quantitative analyses of the HIPEs SANS profiles show that they behave similarly to hydrocarbon-water emulsion analogues, with regard to total interfacial areas and the effects of amphiphile concentration on the underlying structures. Finally, the advantages and disadvantages of both approaches for controlling the physico-chemical properties of liquid/supercritical CO(2) in potential applications are compared and contrasted. These results highlight the importance of using specially designed CO(2)-philic amphiphiles for generating self-assembly structures in dense CO(2).
Collapse
|
20
|
Physicochemical Studies on the Interfacial and Micellization Behavior of CTAB in Aqueous Polyethylene Glycol Media. J SURFACTANTS DETERG 2011. [DOI: 10.1007/s11743-011-1261-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
21
|
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.
Collapse
Affiliation(s)
- Stephen Cummings
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | | | | | | |
Collapse
|
22
|
Blakey I, Thurecht KJ, Whittaker AK. High-pressure real-time 129Xe NMR: monitoring of surfactant conformation during the self-assembly of reverse micelles in supercritical carbon dioxide. Chem Commun (Camb) 2010; 46:2850-2. [DOI: 10.1039/b927029a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
23
|
Abstract
Recent advances in design of surfactants and polymers for liquid and supercritical carbon dioxide, and partially fluorinated alkanes, are reviewed. The focus is on surfactant structure-performance relationships, development of non-fluorinated surfactants, and applications of CO2 continuous dispersions for nanoparticle and organic synthesis. Future prospects for these emerging technologies are discussed, including the need for economically viable and environmentally friendly stabilizers for CO2 dispersions.
Collapse
Affiliation(s)
- Julian Eastoe
- School of Chemistry, University of Bristol, Bristol, UK BS8 1TS.
| | | |
Collapse
|
24
|
Rodrı´guez A, Mar Graciani MD, Fernández G, Moyá ML. Effects of glycols on the thermodynamic and micellar properties of TTAB in water. J Colloid Interface Sci 2009; 338:207-15. [DOI: 10.1016/j.jcis.2009.06.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Revised: 06/01/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
|
25
|
Wang L, Tabor R, Eastoe J, Li X, Heenan RK, Dong J. Formation and stability of nanoemulsions with mixed ionic-nonionic surfactants. Phys Chem Chem Phys 2009; 11:9772-8. [PMID: 19851556 DOI: 10.1039/b912460h] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple, low-energy two-step dilution process has been applied with binary mixtures of ionic-nonionic surfactants to prepare nanoemulsions. The systems consist of water/DDAB-C(12)E(5)/decane. Nanoemulsions were obtained by dilution of concentrates located in bicontinuous microemulsion or lamellar liquid crystal phase regions. The nanoemulsions generated were investigated both by contrast-variation small-angle neutron scattering (SANS) and dynamic light scattering (DLS). The SANS profiles show that C(12)E(5) nanodroplets suffer essentially no structural change on incorporation of the cationic DDAB surfactant, except for increased electrostatic repulsive interactions. Interestingly, SANS indicated that the preferred droplet sizes were hardly affected by the surfactant mixture composition (up to a DDAB molar ratio (m(DDAB)/(m(DDAB) + m(C(12)E(5))) of 0.40) and droplet volume fraction, phi, between 0.006 and 0.120. No notable changes in the structure or radius of nanoemulsion droplets were observed by SANS over the test period of 1 d, although the droplet number intensity decreased significantly in systems stabilized by C(12)E(5) only. However, the DLS sizing shows a marked increase with time, with higher droplet volume fractions giving rise to the largest changes. The discrepancy between apparent nanoemulsion droplet size determined by DLS and SANS data can be attributed to long-range droplet interactions occurring outside of the SANS sensitivity range. The combined SANS and DLS results suggest flocculation is the main mechanism of instability for these nanoemulsions. The flocculation rate is shown to be significantly retarded by addition of the charged DDAB, which may be due to enhanced electrostatic repulsive forces between droplets, leading to improved stability of the nanoemulsions.
Collapse
Affiliation(s)
- Lijuan Wang
- College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China
| | | | | | | | | | | |
Collapse
|
26
|
Debbabi K, Guittard F, Eastoe J, Rogers S, Geribaldi S. Reverse water-in-fluorocarbon microemulsions stabilized by new polyhydroxylated nonionic fluorinated surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8919-8926. [PMID: 19344159 DOI: 10.1021/la803579b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
New polyhydroxylated nonionic perfluorosurfactants CnF2n+1-CH2-O-SO2-NHCONH-C(CH2OH)3 have been synthesized, and their capacity for stabilization of reverse water-in-fluorocarbon microemulsions has been extensively studied. These investigations showed that, regardless of the composition used, transparent one-phase systems could not be obtained if the fluorinated surfactants were used without a sufficient amount of a semifluorinated alcohol. The mixed oil phase used to prepare microemulsions consisted of a 9:1 mixture of perfluorohexane and 1H,1H,2H,2H-perfluorohexan-1-ol. Various scattering techniques, dynamic light scattering (DLS), small-angle X-ray (SAXS), and neutron scattering (SANS) have been used for structural characterization of these fluorinated microemulsions. Valuable information on the size, shape, and internal colloidal structure in these novel fluorinated microemulsions is described and discussed.
Collapse
Affiliation(s)
- Khaled Debbabi
- Institut de Chimie de Nice FR 3037 CNRS, Laboratoire de Chimie des Matériaux Organiques et Métalliques, CMOM, UFR Sciences, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 02, France
| | | | | | | | | |
Collapse
|
27
|
Wang L, Mutch KJ, Eastoe J, Heenan RK, Dong J. Nanoemulsions prepared by a two-step low-energy process. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:6092-6099. [PMID: 18489188 DOI: 10.1021/la800624z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A simple low-energy two-step dilution process has been applied in oil/surfactant/water systems with pentaoxyethylene lauryl ether (C12E5), dodecyldimethylammonium bromide, sodium bis(2-ethylhexyl)sulfosuccinate, sodium n-dodecyl sulfate-pentanol, and hexadecyltrimethylammonium bromide-pentanol. Appropriate formulations were chosen for the concentrate to be diluted with water to generate oil-in-water (O/W) emulsions or nanoemulsions. For the system of decane/C12E5/water, bluish, transparent nanoemulsions having droplet radii of the order of 15 nm were formed, only when the initial concentrate was a bicontinuous microemulsion, whereas opaque emulsions were generated if the concentrate began in an emulsion-phase region. Nanoemulsions generated in the system decane/C12E5/water have been investigated both by dynamic light scattering (DLS) and contrast-variation small-angle neutron scattering (SANS). The SANS profiles show that nanodroplets exist as spherical core-shell (decane-C12E5) particles, which suffer essentially no structural change on dilution with water, at least for volume fractions phi down to 0.060. These results suggest that the nanoemulsion droplet structure is mainly controlled by the phase behavior of the initial concentrate and is largely independent of dilution. A discrepancy between apparent nanoemulsion droplet sizes was observed by comparing DLS and SANS data, which is consistent with long-range droplet interactions occurring outside of the SANS sensitivity range. These combined phase behavior, SANS, and DLS results suggest a different reason for the stability/instability of nanoemulsions compared with earlier studies, and here it is proposed that a general mechanism for nanoemulsion formation is homogeneous nucleation of oil droplets during the emulsification.
Collapse
Affiliation(s)
- Lijuan Wang
- College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China
| | | | | | | | | |
Collapse
|
28
|
Gao N, Dong J, Zhang G, Zhou X, Eastoe J, Mutch KJ, Heenan RK. Surface and micelle properties of novel multi-dentate surfactants. J Colloid Interface Sci 2007; 314:707-11. [PMID: 17644106 DOI: 10.1016/j.jcis.2007.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 06/01/2007] [Accepted: 06/01/2007] [Indexed: 10/23/2022]
Abstract
Novel multi-dentate surfactants, based on alkyl amines of varying hydrophobicity were synthesized, and molecular structures were characterized by IR, UV-vis, NMR and FAB-MS. The new surfactants have good water solubility and are highly efficient at reducing aqueous surface tension. Small-angle neutron scattering (SANS) studies were carried out with aqueous solutions in D(2)O to study aggregation. Spherical micelles were shown to form, and these grow with increasing alkyl chain length; their conformation is unusual compared to conventional linear chain surfactants.
Collapse
Affiliation(s)
- Nan Gao
- College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China
| | | | | | | | | | | | | |
Collapse
|
29
|
Szajdzinska-Pietek E, Sulak K, Dragutan I, Schlick S. ESR study of aqueous micellar solutions of perfluoropolyether surfactants with the use of fluorinated spin probes. J Colloid Interface Sci 2007; 312:405-12. [PMID: 17434178 DOI: 10.1016/j.jcis.2007.03.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/14/2007] [Accepted: 03/15/2007] [Indexed: 11/17/2022]
Abstract
Fluoroalkyl esters of 3-carboxy pyrroline nitroxide, FPn (n=8 and 12), containing (n-2) CF(2) groups in the side-chain, were used as novel ESR spin probes of fluorinated micellar systems. The method was applied to study aqueous solutions of perfluoropolyether surfactants of the general formula Cl(C(3)F(6)O)(2)CF(2)COOX, consisting of two perfluoroisopropoxy units and the counterion X = Na(+) or NH(+)(4). By measuring the change of (14)N hyperfine splitting with surfactant concentration the critical micellar concentration of the ammonium salt was determined at temperatures of 297, 313 and 333 K. The ESR line shape was also examined as a function of surfactant concentration and of temperature in the range 120-360 K. The results are discussed in terms of solubilization and local environment of the probes in micelles of different size and shape, depending on the surfactant concentration and the kind of the counterion.
Collapse
Affiliation(s)
- Ewa Szajdzinska-Pietek
- Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz, Poland.
| | | | | | | |
Collapse
|
30
|
Zheng O, Zhao JX, Yan H, Gao SK. Dilution method study on the interfacial composition and structural parameters of water/C12––C12⋅2Br/n-hexanol/n-heptane microemulsions: Effect of the oxyethylene groups in the spacer. J Colloid Interface Sci 2007; 310:331-6. [PMID: 17303155 DOI: 10.1016/j.jcis.2007.01.056] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 01/10/2007] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
The interfacial composition and the structure of the water/C(12)-EO(x)-C(12).2Br/n-hexanol/n-heptane microemulsion have been investigated by the dilution method. The results showed that C(12)-EO(x)-C(12).2Br formed a stable water/oil microemulsion with the assistance of n-hexanol. Owing to the relatively large size of the head group, more n-hexanol molecules are populated on the droplet surface than in the C(12)-2-C(12).2Br system. The radius of the water pool of the C(12)-EO(3)-C(12).2Br system is not as sensitive to W(0) as in the C(12)-2-C(12).2Br system. Another feature of the present system is that its droplet size is considerably smaller than that of the C(12)-2-C(12).2Br system, and also those of the CPC and CTAB systems at relative high water content. This provides a potential application for the synthesis of nanoparticles with small size.
Collapse
Affiliation(s)
- Ou Zheng
- Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, People's Republic of China
| | | | | | | |
Collapse
|
31
|
Eastoe J, Gold S, Steytler DC. Surfactants for CO2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9832-42. [PMID: 17106970 DOI: 10.1021/la060764d] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
For some 15 years the attainment of efficient, nonfluorinated CO2-active surfactants has been a Holy Grail for researchers spanning pure and applied chemical sciences. This article tells the story of small-molecule CO2-active surfactants, from the first tentative observations with fluorinated compounds in 1991 up to recently discovered fluorine-free oxygenated amphiphiles.
Collapse
Affiliation(s)
- Julian Eastoe
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | | |
Collapse
|
32
|
Rodríguez A, del Mar Graciani M, Muñoz M, Robina I, Moya ML. Effects of ethylene glycol addition on the aggregation and micellar growth of gemini surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9519-25. [PMID: 17073474 DOI: 10.1021/la062225e] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Micellization of three didodecyl dicationic dibromide gemini surfactants with different methylene spacer lengths, 12-s-12,2Br- where s = 3-5 methylene groups, has been investigated in water-ethylene glycol, EG, mixtures with weight percentages of EG up to 50%. Subsequently, effects of the addition of the organic solvent on the micellar growth of these surfactants and on the surfactant concentration range where sphere-to-rod transitions occur were studied by means of steady-state and time-resolved fluorescence quenching and spectroscopic measurements. Results show that an increase in the weight percentage of ethylene glycol added to aqueous 12-s-12,2Br- (s = 3-5) micellar solutions causes the sphere-to-rod transition to occur at higher surfactant concentrations than in pure water. The diminution in the average aggregation number, N(agg), when wt % EG increases, provoked by the decrease in the interfacial Gibbs energy contribution to DeltaG degrees M, is the main factor responsible for this observation. The decrease in N(agg) is accompanied by a decrease in the ionic interactions and the extra packing contribution to the deformation of the surfactants tails, making formation of cylindrical micelles less favorable. Besides, an increase in the solvent content and polarity of the interfacial region does not favor formation of direct ion pairs, decreasing the tendency of micelles to grow.
Collapse
Affiliation(s)
- Amalia Rodríguez
- Departamento de Química Física, Universidad de Sevilla, C/Profesor García Gonzalez 2, 41012 Sevilla. Spain
| | | | | | | | | |
Collapse
|
33
|
Bowers J, Amos KE, Bruce DW, Heenan RK. Surface and aggregation behavior of aqueous solutions of Ru(II) metallosurfactants: 4. Effect of chain number and orientation on the aggregation of [Ru(bipy)2(bipy')]Cl2 complexes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:5696-706. [PMID: 15952812 DOI: 10.1021/la050241q] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The structure of aggregates formed by eight surfactant [Ru(bipy)2(p,p'-dialkyl-2,2'-bipy)]Cl2 complexes-which we express as Ru(p)(q)Cn, where n (=12 or 19) is the alkyl chain length, p (=4 or 5) refers to the substitution position on the bipyridine ligand, and q (=1 or 2) is the number of substituted alkyl chains-in aqueous solutions has been examined using small-angle neutron scattering for a range of concentrations close to the critical micelle concentration and for several combinations of n, p, and q. A number of general results emerge. The double-chain surfactants possess a smaller headgroup charge but a larger aggregate size than their single-chain analogues. Over the concentration range studied, the micelles of the single-chain surfactants grow as the concentration is increased, whereas for the double-chain systems, the aggregate size remains unchanged. For both single- and double-chain surfactants, an increase in alkyl chain length is accompanied by an expected increase in aggregate size and an increase in average headgroup charge. The aggregates formed in solutions of resolved double-chain complexes are larger than those found in solutions of racemic mixtures. The Ru(4)(1)C12 and Ru(5)(1)C12 systems form aggregates with high water content. Variation of the substitution position for the single-chain surfactants produces dramatic changes in the structure of the micelles. The aggregates formed in solutions of Ru(4)(1)C19 and Ru(5)(1)C19 display particularly different structures. The Ru(4)(1)C19 system forms essentially spherical aggregates. In contrast, in the Ru(5)(1)C19 system, wormlike aggregates are formed in which the rigid rodlike sections appear to undergo a transition from a noninterdigitated to an interdigitated structure as the concentration is increased. For double-chain surfactants, the aggregation number for p = 4 surfactants is considerably larger than that for p = 5 surfactants.
Collapse
Affiliation(s)
- James Bowers
- Department of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD, United Kingdom.
| | | | | | | |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- Audrey Dupont
- School of Chemistry, University of Bristol, Bristol, BS8 1TS United Kingdom
| | | | | | | | | | | | | |
Collapse
|