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Tucker IM, Burley A, Petkova RE, Hosking SL, Webster J, Li P, Ma K, Doutch J, Penfold J, Thomas RK. Self-assembly in escin-nonionic surfactant mixtures: from micelles to vesicles. J Colloid Interface Sci 2022; 626:305-313. [DOI: 10.1016/j.jcis.2022.06.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/13/2022] [Accepted: 06/23/2022] [Indexed: 11/17/2022]
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Penfold J, Thomas RK. Neutron reflection and the thermodynamics of the air-water interface. Phys Chem Chem Phys 2022; 24:8553-8577. [PMID: 35352746 DOI: 10.1039/d2cp00053a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solution. Previously, adsorption at air-water interfaces has been determined by applying the Gibbs equation to surface tension (ST) measurements, which requires assumptions about the composition of the surface and about the activity of the solute in the bulk, which, in turn, means that in practice the surface is assumed to consist of the pure solute or of a mixture of pure solutes, and that the activity of the solute in the bulk solution is known. The use of NR in combination with ST-Gibbs measurements makes it possible to (i) avoid these assumptions and hence understand several patterns of ST behaviour previously considered to be anomalous and (ii) to start to analyse quantitatively the behaviour of mixed surfactants both below and above the critical micelle concentration. These two developments in our understanding of the thermodynamics of the air-water interface are described with recent examples.
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Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxon, UK. .,Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
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Penfold J, Thomas RK. Recent developments and applications of the thermodynamics of surfactant mixing. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1649489] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, UK
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Robert K. Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
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Surfactant-Amino Acid and Surfactant-Surfactant Interactions in Aqueous Medium: a Review. Appl Biochem Biotechnol 2015; 176:2077-106. [PMID: 26160314 DOI: 10.1007/s12010-015-1712-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
An overview of surfactant-amino acid interactions mainly in aqueous medium has been discussed. Main emphasis has been on the solution thermodynamics and solute-solvent interactions. Almost all available data on the topic has been presented in a lucid and simple way. Conventional surfactants have been discussed as amphiphiles forming micelles and amino acids as additives and their effect on the various physicochemical properties of these conventional surfactants. Surfactant-surfactant interactions in aqueous medium, various mixed surfactant models, are also highlighted to assess their interactions in aqueous medium. Finally, their applied part has been taken into consideration to interpret their possible uses.
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Liang CH, Yeh LH, Liao PW, Chou TH. Characterization and in vitro biocompatibility of catanionic assemblies formed with oppositely charged dicetyl amphiphiles. Colloids Surf B Biointerfaces 2015; 126:10-7. [DOI: 10.1016/j.colsurfb.2014.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 12/02/2014] [Accepted: 12/04/2014] [Indexed: 01/08/2023]
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Kawabata Y, Hayashi K, Kanao T, Ishikawa A. Bilayer structure of ester-amide-type cationic surfactants in a dilute aqueous solution. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.08.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Leclercq L, Lubart Q, Aubry JM, Nardello-Rataj V. Modeling of multiple equilibria in the self-aggregation of di-n-decyldimethylammonium chloride/octaethylene glycol monododecyl ether/cyclodextrin ternary systems. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:6242-6252. [PMID: 23627717 DOI: 10.1021/la400782c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The surface tension equations of binary surfactant mixtures (di-n-decyldimethylammonium chloride and octaethylene glycol monododecyl ether) are established by combining the Szyszkowski equation of surfactant solutions, the ideal or nonideal mixing theory, and the phase separation model. For surfactant mixtures, the surface tension at the air-water interface is calculated using nonideal theory due to synergism between the two adsorbed surfactant types. The incorporation of cyclodextrin complexation model to the surface tension equations gives a robust model for the description of the surface tension isotherms of binary, ternary, and more complex systems involving numerous inclusion complexes. The surface tension data obtained experimentally shows excellent agreement with the theoretical model below and above the formation of micelles. The strong synergistic effect observed between the two surfactants is disrupted by the presence of CDs, leading to ideal behavior of ternary systems. Indeed, depending on the nature of the cyclodextrin (i.e., α, β, or γ), which allows a tuning of the cavity size, the binding constants with the surfactants are modified as well as the surface properties due to strong modification of equilibria involved in the ternary mixture.
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Affiliation(s)
- Loïc Leclercq
- Université Lille 1 , EA Chimie Moléculaire et Formulation 4478, Equipe Oxydation et Physico-chimie de la Formulation, Bât. C6, F-59655 Villeneuve d'Ascq Cedex, France
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Penfold J, Thomas RK. The limitations of models of surfactant mixing at interfaces as revealed by neutron scattering. Phys Chem Chem Phys 2013; 15:7017-27. [DOI: 10.1039/c3cp00104k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rauwel G, Leclercq L, Criquelion J, Aubry JM, Nardello-Rataj V. Aqueous mixtures of di-n-decyldimethylammonium chloride/polyoxyethylene alkyl ether: dramatic influence of tail/tail and head/head interactions on co-micellization and biocidal activity. J Colloid Interface Sci 2012; 374:176-86. [PMID: 22402182 DOI: 10.1016/j.jcis.2012.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 02/02/2012] [Accepted: 02/04/2012] [Indexed: 11/30/2022]
Abstract
Mixed aggregate formation and synergistic interactions of binary surfactant mixtures of di-n-decyldimethylammonium chloride, [DiC(10)][Cl], with polyoxyethylene alkyl ethers, C(i)E(j) (i=10, 12, j=4, 6, 8), have been investigated for various [DiC(10)][Cl]/C(i)E(j) ratios. The critical aggregation concentration of the binary mixtures has been determined by tensiometry, and the aggregate characteristics (i.e., size and composition, free ammonium concentration) have been estimated using the pulsed field gradient NMR spectroscopy and a [DiC(10)]-selective electrode. Diffusion coefficient measurements of micelles confirmed the synergistic interaction between the surfactants. It is thus shown that the formation of surface monolayers and mixed aggregates from [DiC(10)][Cl]/C(10)E(j) mixtures is driven by both tail/tail and head/head interactions, whereas [DiC(10)][Cl]/C(12)E(j) co-aggregation is mainly driven by tail/tail interactions. As a consequence, the co-aggregation phenomenon notably influences the biocidal activity of [DiC(10)][Cl] on the Candida albicans fungi. In the presence of C(12)E(j), the biocidal activity of the ammonium salt is inhibited due to the trapping of the cationic surfactants in the mixed aggregates, whereas in the presence of C(10)E(j), the biocidal activity of the surfactant mixture is maintained. The mode of action is also confirmed by a faster increase in the zeta potential of a C. albicans suspension in the presence of [DiC(10)][Cl]/C(10)E(8) than in the presence of [DiC(10)][Cl]/C(12)E(8). Therefore, a judicious adjustment of the alkyl (i) and polyoxyethylene (j) chain lengths of C(i)E(j) avoids its antagonistic effect on the biocidal activity of [DiC(10)][Cl].
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Affiliation(s)
- Gaétan Rauwel
- Laboratoires Anios, Pavé du Moulin, F-59260 Hellemmes Lille, France
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Park IJ, Lee BH. Mixed Micellization of Sodium Dodecylbenzene Sulfonate with Polyoxyethylene Lauryl Ether Surfactants (POLE4 and POLE23) in n-Butanol Aqueous Solution. J SURFACTANTS DETERG 2011. [DOI: 10.1007/s11743-011-1287-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Grillo I, Penfold J. Self-assembly of mixed anionic and nonionic surfactants in aqueous solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7453-7463. [PMID: 21595448 DOI: 10.1021/la200874g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present the phase diagram and the microstructure of the binary surfactant mixture of AOT and C(12)E(4) in D(2)O as characterized by surface tension and small angle neutron scattering. The micellar region is considerably extended in composition and concentration compared to that observed for the pure surfactant systems, and two types of aggregates are formed. Spherical micelles are present for AOT-rich composition, whereas cylindrical micelles with a mean length between 80 and 300 Å are present in the nonionic-rich region. The size of the micelles depends on both concentration and molar ratio of the surfactant mixtures. At higher concentration, a swollen lamellar phase is formed, where electrostatic repulsions dominate over the Helfrich interaction in the mixed bilayers. At intermediate concentrations, a mixed micellar/lamellar phase exists.
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Affiliation(s)
- I Grillo
- Institut Laue Langevin, DS/LSS, 6 rue Jules Horowitz, B.P. 156, 38042 Grenoble Cedex 9.
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Lee BH, Park IJ. Comparative Study on the Micellization of SDS/Brij 30, DBS/Brij 30, and SDS/DBS Mixed Surfactant Systems in Pure Water. JOURNAL OF THE KOREAN CHEMICAL SOCIETY-DAEHAN HWAHAK HOE JEE 2011. [DOI: 10.5012/jkcs.2011.55.3.379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Tucker I, Penfold J, Thomas RK, Dong CC, Golding S, Gibson C, Grillo I. Surface and solution properties of anionic/nonionic surfactant mixtures of alkylbenzene sulfonate and triethyleneglycol decyl ether. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10614-10626. [PMID: 20423066 DOI: 10.1021/la100846b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The surface adsorption behavior and the solution microstructure of mixtures of the C(6) isomer of anionic surfactant sodium para-dodecyl benzene sulfonate, ABS, with nonionic surfactant monodecyl triethyleneglycol ether, C(10)E(3,) have been investigated using a combination of neutron reflectivity, NR, and small-angle neutron scattering, SANS. In solution, the mixing of C(10)E(3) and ABS results in the formation of small globular micelles over most of the composition range (100:0 to 20:80 ABS/C(10)E(3)). Planar aggregates (lamellar or unilamellar vesicles, ULV) are observed for solution compositions rich in the nonionic surfactant (>80 mol % nonionic). Prior to the transition to planar aggregates, the micelle aggregation number increases with increasing nonionic composition. The lamellar-phase region is preceded by a narrow range of composition over which mixtures of micelles and small unilamellar vesicles coexist. The variation in surface absorption behavior with solution composition shows a strong surface partitioning of the more surface-active component, C(10)E(3). This pronounced departure from ideal mixing is not readily explained by existing surfactant mixing theories. In the presence of Ca(2+) ions, a more complex evolution of solution phase behavior with solution composition is observed. The lamellar-phase region occurs over a broader range of solution compositions at the expense of the small-vesicle phase. The phase boundaries are shifted to lower nonionic compositions, and the extent to which the solution-phase diagrams are modified increases with increasing calcium ion concentration. The SANS data for the large planar aggregates are consistent with large polydisperse flexible unilamellar vesicles. In the presence of Ca(2+) ions, the surface adsorption patterns become more consistent with ideal mixing in the nonionic-rich region of the surface-phase diagram. However, in the ABS-rich regions the surface behavior is more complex because of the spontaneous formation of more complex surface microstructures (bilayers to multilayers). Both in water and in the presence of Ca(2+) ions the variations in the surface adsorption behavior and in the solution mesophase structure do not appear to be closely correlated.
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Affiliation(s)
- I Tucker
- Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral, UK.
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Dong R, Hao J. Complex Fluids of Poly(oxyethylene) Monoalkyl Ether Nonionic Surfactants. Chem Rev 2010; 110:4978-5022. [DOI: 10.1021/cr9003743] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Renhao Dong
- Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, PR China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, PR China
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Comparative Study on the Mixed Micellizations of Anionic Surfactant (DBS) with Nonionic Surfactnats (Brij 30 and Brij 35). JOURNAL OF THE KOREAN CHEMICAL SOCIETY-DAEHAN HWAHAK HOE JEE 2009. [DOI: 10.5012/jkcs.2009.53.5.491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Gröhn F, Klein K, Koynov K. A Novel Type of Vesicles Based on Ionic and π
-π
Interactions. Macromol Rapid Commun 2009; 31:75-80. [DOI: 10.1002/marc.200900386] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 07/31/2009] [Indexed: 11/10/2022]
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Debnath A, Ayappa KG, Kumaran V, Maiti PK. The Influence of Bilayer Composition on the Gel to Liquid Crystalline Transition. J Phys Chem B 2009; 113:10660-8. [DOI: 10.1021/jp901551d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ananya Debnath
- Department of Chemical Engineering, Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - K. G. Ayappa
- Department of Chemical Engineering, Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - V. Kumaran
- Department of Chemical Engineering, Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Prabal K. Maiti
- Department of Chemical Engineering, Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
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Tucker I, Penfold J, Thomas RK, Bradbury R, Grillo I. Transition from vesicles to small nanometer scaled vesicles, arising from the manipulation of curvature in dialkyl chain cationic/nonionic surfactant mixed aggregates by the addition of straight chain alkanols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:4934-4944. [PMID: 19256459 DOI: 10.1021/la804116d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The addition of straight chain alkanols to the dialkyl chain cationic/nonionic surfactant mixtures of dihexadecyl dimethyl ammonium bromide, DHDAB, and dodecaethylene monododecyl ether, C(12)E(12), has been used to manipulate the mean curvature of the self-assembled aggregates. This induces some significant structural changes and notably the formation of small unilamellar vesicles, nanometer scaled vesicles, L(sv). These structural changes have been measured and quantified using small angle neutron scattering, SANS. At a solution concentration of 25 mM, the DHDAB/C(12)E(12) mixtures have a structural evolution, from C(12)E(12) rich to DHDAB rich solution compositions, of small globular micelles, L(1), to micellar/vesicle coexistence, L(1)/L(v) or L(v)/L(1), to vesicle structures, L(v), bilamellar or multilamellar vesicles, blv or mlv. The impact of the addition of straight chain alkanols (in the range octanol to hexadecanol) depends upon the alkyl chain length and the amount of alcohol added. Furthermore, the effect of the addition of octanol and decanol appears to be distinctly different from that of the larger straight chain alkanols of dodecanol and hexadecanol. For the addition of octanol and decanol to C(12)E(12) rich DHDAB/C(12)E(12) mixtures, the alcohol is solubilized into the micellar core, and as the amount of alcohol added increases, significant micellar growth is ultimately observed. However, notably at intermediate DHDAB/C(12)E(12) solution compositions, in the region of L(1)/L(v) or L(v)/L(1) coexistance in the absence of alcohol, the addition of octanol or decanol promotes the formation of relatively small unilamellar vesicles, L(sv), nanometer sized vesicles, with a mean diameter in the range 70-140 A. For solutions that are rich in DHDAB, the addition of octanol or decanol results in a transition to L(v)/L(sv) coexistence and ultimately to L(v) formation. In contrast, the addition of the larger straight chain length alkanols, dodecanol or hexadecanol, to DHDAB/C(12)E(12) mixtures results in a somewhat different behavior. In this case, the addition of dodecanol or hexadecanol results in the transition from L(1) to L(1)/L(v) to L(v) occurring for solutions less rich in DHDAB than is observed in the absence of alcohol. That is, there is an enhanced tendency toward the formation of structures with a lower net curvature, either blv or mlv. Notably, for these mixtures, the small unilamellar nanometer scaled vesicle phase, L(sv), is absent.
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Affiliation(s)
- I Tucker
- Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral, United Kingdom
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Tucker I, Penfold J, Thomas RK, Tildesleyt DJ. Interplay between the surface adsorption and solution-phase behavior in dialkyl chain cationic-nonionic surfactant mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3924-3931. [PMID: 18998711 DOI: 10.1021/la801302z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Neutron reflectivity, NR, and surface tension have been used to study the adsorption at the air-solution interface of mixtures of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) and the nonionic surfactants monododecyl triethylene glycol (C12E3), monododecyl hexaethylene glycol (C12E6), and monododecyl dodecaethylene glycol (C12E12). The adsorption behavior of the surfactant mixtures with solution composition shows a marked departure from ideal mixing that is not consistent with current theories of nonideal mixing. For all three binary surfactant mixtures there is a critical composition below which the surface is totally dominated by the cationic surfactant. The onset of nonionic surfactant adsorption (expressed as a mole fraction of the nonionic surfactant) increases in composition as the ethylene oxide chain length of the nonionic cosurfactant increases from E3 to E12. Furthermore, the variation in the adsorption is strongly correlated with the variation in the phase behavior of the solution that is in equilibrium with the surface. The adsorbed amounts of DHDAB and the nonionic cosurfactants have been used to estimate the monomer concentration that is in equilibrium with the surface and are shown to be in reasonable qualitative agreement with the variation in the mixed critical aggregation concentration (cac).
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Affiliation(s)
- I Tucker
- Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral, UK
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Grillo I, Penfold J, Tucker I, Cousin F. Spontaneous formation of nanovesicles in mixtures of nonionic and dialkyl chain cationic surfactants studied by surface tension and SANS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3932-3943. [PMID: 19714821 DOI: 10.1021/la802435h] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Surface tension and small-angle neutron scattering have been used to characterize the surface properties and the structure of the aggregates formed in the dilute part of the ternary system didodecyldimethyl ammonium bromide, DDAB/tetraethylene glycol monododecyl ether, C12E4/D2O. For surfactant molar ratios, Rn, between 0.3 and 1 (pure DDAB), the surface tension measurements show the existence of two break points at concentrations of around 10(-5) and 10(-3) mol/L, respectively. The SANS measurements have shown that the first break point corresponds to a critical micellar concentration (cmc) and the second one corresponds to a critical vesicle concentration (cvc). In the intermediate composition range, Rn = 0.3-0.8, very small unilamellar vesicles (nanovesicles) are formed with the inner radius varying between 28 and 85 A and a bilayer thickness of approximately 23 A. At Rn = 0.8, we observed a transition from small vesicles (V) to large bilamellar or multilamellar vesicles (BLV, MLV) with a relatively large lamellar periodicity of around 1000 A. In the nonionic-rich region below Rn = 0.3, more classical surface tension behavior was observed, with only one break point corresponding to the onset of formation of small globular micelles.
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Affiliation(s)
- I Grillo
- Institut Laue Langevin, 6 rue Jules Horowitz, B.P. 156, 38042 Grenoble Cedex 9, France.
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Tucker I, Penfold J, Thomas RK, Grillo I. Monomer-aggregate exchange rates in dialkyl chain cationic-nonionic surfactant mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:2661-2666. [PMID: 19437689 DOI: 10.1021/la803329a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The monomer-aggregate exchange rate in self-assembled dialkyl chain cationic-nonionic mixed surfactant aggregates has been studied using small-angle neutron scattering, SANS, and a stopped-flow apparatus. SANS was used to follow the evolution of the structure with time of an equimolar mixture of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide, DHDAB, in D2O with the nonionic surfactant dodecaethylene monododecyl ether, C12E12, in D2O at a solution concentration of 1.5 mM. With increasing time, the bilamellar vesicle structure, blv, of DHDAB and the globular micellar structure, L1, of C12E12 evolved to a lamellar (Lbeta or Lalpha)/micellar (L1) coexistence. Measurements were made for the isotopically labeled combinations of hydrogeneous DHDAB (h-DHDAB) and alkyl chain deuterium-labeled C12E12 (d-C12E12) in D2O such that the lamellar contribution is the predominantly visible contribution to the scattering. From the variation (decrease) in the scattering intensity with time (measured at a scattering vector of approximately 0.014 angstroms(-1)), a characteristic time was measured at 32 degrees C (T < Lbeta/Lalpha transition temperature) and at 46 degrees C (T > Lbeta/Lalpha). The characteristic time was approximately 130 min and a few seconds respectively, indicating a dramatic change in the monomer/aggregate exchange rate between the solid-like Lbeta and fluid-like Lalpha phases. The characteristic time of approximately 130 min in the Lbeta phase is indicative of a slow monomer-aggregate exchange rate and is consistent with the slow kinetics of adsorption of DHDAB and DHDAB/nonionic surfactant mixtures observed at the air-water interface. This slow adsorption kinetics was assumed to arise from near-surface depletion effects associated with slow monomer/aggregate exchange rates, and these results support and reinforce that hypothesis.
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Affiliation(s)
- I Tucker
- Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral, UK.
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