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Mysona JA, McCormick AV, Morse DC. Nonlinear dynamics in micellar surfactant solutions. I. Kinetics. Phys Rev E 2022; 105:034602. [PMID: 35428164 DOI: 10.1103/physreve.105.034602] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
This is the first of a pair of articles that present the theory of kinetic and transport phenomena in micelle-forming surfactant solutions in a form that facilitates discussion of large deviations from equilibrium. Our goal is to construct approximate but robust reduced models for both homogeneous and inhomogeneous systems as differential equations for unimer concentration c_{1}, micelle number concentration c_{m}, average micelle aggregation number q and (optionally) aggregation number variance σ_{m}^{2}. This first article discusses kinetics in homogeneous solutions. We focus particularly on developing models that can describe both weakly perturbed states and states in which c_{1} is suppressed significantly below the critical micelle concentration, which leads to rapid shrinkage and dissociation of any remaining micelles. This focus is motivated by the strong local suppression of c_{1} that is predicted to occur near interfaces during some adsorption processes that are considered in the second article. Toward this end, we develop a general nonlinear theory of fast stepwise processes for systems that may be subjected to large changes in q and c_{1}. This is combined with the existing nonlinear theory of slow association and dissociation processes to construct a general model for systems governed by stepwise reaction kinetics. We also consider situations in which the slow process of micelle creation and destruction instead occurs primarily by micelle fission and fusion, and analyze the dependencies of micelle lifetime and the slow relaxation time upon surfactant concentration in systems controlled by either association-dissociation or fission-fusion mechanisms.
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Affiliation(s)
- Joshua A Mysona
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Alon V McCormick
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - David C Morse
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
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2
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Pantelidou MS, García Daza FA, Avalos JB, Mackie AD. Universal Scaling for the Exit Dynamics of Block Copolymers from Micelles at Short and Long Time Scales. Macromolecules 2022; 55:914-927. [PMID: 35177871 PMCID: PMC8842487 DOI: 10.1021/acs.macromol.1c02387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/01/2022] [Indexed: 11/29/2022]
Abstract
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The correlation function
for the exit of poloxamer copolymers from
equilibrated micelles is found to show up to four regimes depending
on the chain flexibility: an initial fast reorganization, a logarithmic
intermediate regime, followed by an exponential intermediate regime,
and a final exponential decay. The logarithmic intermediate regime
has been observed experimentally and attributed to the polydispersity
of the polymer samples. However, we present dynamic single-chain mean-field
theory simulations with chains of variable flexibility which show
the same logarithmic relaxation but with strictly monodisperse systems.
In agreement with our previous studies, we propose that this logarithmic
response arises from a degeneracy of energy states of the hydrophobic
block in the micelle core. For this to occur, a sufficiently large
number of degenerate conformational states are required, which depend
on the polymer flexibility and therefore should not be present for
rigid polymers. Experimental results for monodisperse polymeric samples
claiming the absence of such a logarithmic response may also lack
a sufficient number of hydrophobic blocks for the required number
of configurational states for this type of response to be seen. The
insight gained from analyzing the simulation results allows us to
propose a modified Eyring equation capable of reproducing the observed
dynamic behavior. On scaling experimental results from different sources
and systems according to this equation, we find a unique master curve
showing a universal nature of the intermediate regimes: the logarithmic
regime together with the secondary exponential decay. The terminal
exponential regime at long times proposed by the standard Halperin
and Alexander model is beyond the range of the data analyzed in this
article. The universality observed suggests an entropic origin of
the short-time dynamic response of this class of systems rather than
the polydispersity.
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Affiliation(s)
- Maria S. Pantelidou
- Departament d’Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Tarragona 43007, Spain
| | - Fabián A. García Daza
- Department of Chemical Engineering, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Josep Bonet Avalos
- Departament d’Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Tarragona 43007, Spain
| | - Allan D. Mackie
- Departament d’Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Tarragona 43007, Spain
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Mysona JA, McCormick AV, Morse DC. Simulation of diblock copolymer surfactants. II. Micelle kinetics. Phys Rev E 2019; 100:012603. [PMID: 31499829 DOI: 10.1103/physreve.100.012603] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Indexed: 06/10/2023]
Abstract
Molecular dynamics (MD) simulations are used to measure dynamical properties of a simple bead-spring model of A-B diblock copolymer molecules, and to characterize rates and mechanisms of several dynamical processes. Dynamical properties are analyzed within the context of a kinetic population model that allows for both stepwise insertion and expulsion of individual free molecules and occasional fission and fusion of micelles. Kinetic coefficients for stepwise processes and micelle fission have been extracted from MD simulations of individual micelles. Insertion of a free surfactant molecule into a preexisting micelle is shown to be a completely diffusion-controlled process for the model studied here. Estimates are given for rates of rare events that create and destroy entire micelles by competing mechanisms involving stepwise association and dissociation or fission and fusion. Both mechanisms are shown to be relevant over the range of parameters studied here, with association and dissociation dominating in systems with more soluble surfactants and fission and fusion dominating in systems with less soluble surfactants.
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Affiliation(s)
- Joshua A Mysona
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - Alon V McCormick
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
| | - David C Morse
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA
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4
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Biswas R, Bagchi B. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:013001. [PMID: 29205175 DOI: 10.1088/1361-648x/aa9b1d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water-surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface-water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of the same due to interaction with the surfaces.
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Sahara H, Harada S. Calorimetric Study of Micelle Formation of Alkylammonium Chlorides in Water. J Oleo Sci 2018; 67:1417-1424. [DOI: 10.5650/jos.ess18007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ghosh R, Samanta T, Banaerjee S, Biswas R, Bagchi B. Spatio-temporal correlations in aqueous systems: computational studies of static and dynamic heterogeneity by 2D-IR spectroscopy. Faraday Discuss 2015; 177:313-28. [PMID: 25692942 DOI: 10.1039/c4fd00201f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Local heterogeneity is ubiquitous in natural aqueous systems. It can be caused locally by external biomolecular subsystems like proteins, DNA, micelles and reverse micelles, nanoscopic materials etc., but can also be intrinsic to the thermodynamic nature of the aqueous solution itself (like binary mixtures or at the gas-liquid interface). The altered dynamics of water in the presence of such diverse surfaces has attracted considerable attention in recent years. As these interfaces are quite narrow, only a few molecular layers thick, they are hard to study by conventional methods. The recent development of two dimensional infra-red (2D-IR) spectroscopy allows us to estimate length and time scales of such dynamics fairly accurately. In this work, we present a series of interesting studies employing two dimensional infra-red spectroscopy (2D-IR) to investigate (i) the heterogeneous dynamics of water inside reverse micelles of varying sizes, (ii) supercritical water near the Widom line that is known to exhibit pronounced density fluctuations and also study (iii) the collective and local polarization fluctuation of water molecules in the presence of several different proteins. The spatio-temporal correlation of confined water molecules inside reverse micelles of varying sizes is well captured through the spectral diffusion of corresponding 2D-IR spectra. In the case of supercritical water also, we observe a strong signature of dynamic heterogeneity from the elongated nature of the 2D-IR spectra. In this case the relaxation is ultrafast. We find remarkable agreement between the different tools employed to study the relaxation of density heterogeneity. For aqueous protein solutions, we find that the calculated dielectric constant of the respective systems unanimously shows a noticeable increment compared to that of neat water. However, the 'effective' dielectric constant for successive layers shows significant variation, with the layer adjacent to the protein having a much lower value. Relaxation is also slowest at the surface. We find that the dielectric constant achieves the bulk value at distances more than 3 nm from the surface of the protein.
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Affiliation(s)
- Rikhia Ghosh
- SSCU, Indian Institute of Science, Bangalore 560012, India.
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Nishikawa S, Kawahara T, Tominaga N, Sugiyama K, Mizuta K. Study of Aqueous Solutions of Surfactants in the Presence of Alcohols by Means of Ultrasonic Relaxation. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2014. [DOI: 10.1246/bcsj.20140013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
| | - Takahiro Kawahara
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Naotaka Tominaga
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Koutarou Sugiyama
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
| | - Koutarou Mizuta
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University
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Biswas R, Furtado J, Bagchi B. Layerwise decomposition of water dynamics in reverse micelles: A simulation study of two-dimensional infrared spectrum. J Chem Phys 2013; 139:144906. [DOI: 10.1063/1.4824446] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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9
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Hanke E, Telgmann T, Kaatze U. Monomer Exchange Kinetics, Dynamics of Concentration Fluctuations, and Chain Isomerization of Nonionic Surfactant/Water Systems. Evidence from Broadband Ultrasonic Spectra. TENSIDE SURFACT DET 2013. [DOI: 10.3139/113.100247] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Ultrasonic absorption spectra, measured between 0.1 and 2000 MHz, are discussed for a variety of poly(ethylene glycol) monoalkyl ether/water (CiEj=H2O) mixtures. Depending on the temperature, the surfactant concentration, and on the length of the hydrophobic (Ci) as well as the hydrophilic part (Ej) of the surfactant molecules, the spectra reveal a multitude of shapes. The set of spectra, however, can be consistently described considering (i) a relaxation term representing the monomer exchange of the micellar solutions, (ii) another one that reflects the local fluctuations in the surfactant concentration, and, with several systems, (iii) additional terms due to CiEj associations or conformational isomerizations. The parameters of these terms are discussed in the light of relevant models. Evidence is presented for a more general view of a fluctuation controlled monomer exchange mechanism that combines aspects of both theoretical models, the micelle formation/decay kinetics and dynamics of local concentration fluctuations.
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Naumann P, Becker N, Datta S, Sottmann T, Wiegand S. Soret Coefficient in Nonionic Microemulsions: Concentration and Structure Dependence. J Phys Chem B 2013; 117:5614-22. [DOI: 10.1021/jp401701u] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Philipp Naumann
- Forschungszentrum Jülich GmbH, ICS - Soft Condensed Matter, D-52428
Jülich, Germany
| | - Nils Becker
- Universität zu Köln, Physical Chemistry, 50939 Cologne, Germany
| | - Sascha Datta
- Universität zu Köln, Physical Chemistry, 50939 Cologne, Germany
| | - Thomas Sottmann
- Universität zu Köln, Physical Chemistry, 50939 Cologne, Germany
| | - Simone Wiegand
- Forschungszentrum Jülich GmbH, ICS - Soft Condensed Matter, D-52428
Jülich, Germany
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11
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Bhattacharjee JK, Kaatze U. Fluctuations near the critical micelle concentration. II. Ultrasonic attenuation spectra and scaling. J Phys Chem B 2013; 117:3798-805. [PMID: 23506227 DOI: 10.1021/jp401120x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Based on a thermodynamic model of amphiphile solutions derived in the first part of the paper, the ultrasonic attenuation of such systems has been considered theoretically, including fluctuations of local concentrations and micelle sizes. At amphiphile concentrations smaller than the critical micelle concentration (cmc), scaling behavior in terms of the concentration distance to the cmc is predicted by theory, in fair agreement with experimental evidence. The scaling function in the sound attenuation below the cmc reveals the unsymmetric broadening in the spectra that clearly emerges from measurements when approaching the cmc. The shape of the scaling function corresponds to the experimental spectra of solutions with comparatively large cmc as well as with the relaxation spectral function of the unifying model of non-critical concentration fluctuations. Above the cmc, an additional relaxation term is predicted in correspondence with the Landau-Khalatnikov term in the sound attenuation of superfluid helium. This term is difficult to verify by measurements because, in the relevant frequency range, other processes may also contribute the ultrasonic attenuation spectra.
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12
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Bhattacharjee JK, Kaatze U. Fluctuations Near the Critical Micelle Concentration. I. Premicellar Aggregation, Relaxation Rate, and Isentropic Compressibility. J Phys Chem B 2013; 117:3790-7. [DOI: 10.1021/jp4011185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Udo Kaatze
- Drittes Physikalisches
Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz
1, 37077 Göttingen, Germany
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13
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Kaatze U. Kinetics of Micelle Formation and Concentration Fluctuations in Solutions of Short-Chain Surfactants. J Phys Chem B 2011; 115:10470-7. [DOI: 10.1021/jp205372g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- U. Kaatze
- Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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14
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Polacek R, Kaatze U. Micelle and oligomer kinetics in aqueous solutions of n-octylammonium chloride: Monomer exchange, protrusion and chain isomerization. J Mol Liq 2010. [DOI: 10.1016/j.molliq.2010.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Biswas R, Bagchi B. A kinetic Ising model study of dynamical correlations in confined fluids: Emergence of both fast and slow time scales. J Chem Phys 2010; 133:084509. [DOI: 10.1063/1.3474948] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Bressel K, Muthig M, Prévost S, Grillo I, Gradzielski M. Mesodynamics: watching vesicle formation in situ by small-angle neutron scattering. Colloid Polym Sci 2010. [DOI: 10.1007/s00396-010-2212-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Haller J, Kaatze U. Monomer Exchange and Rotational Isomerization of Alkyl Monoglycosides in Water. J Phys Chem B 2009; 113:12283-92. [DOI: 10.1021/jp905523p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Julian Haller
- Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Udo Kaatze
- Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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Haller J, Kaatze U. Octylglucopyranoside and cyclodextrin in water. Self-aggregation and complex formation. J Phys Chem B 2009; 113:1940-7. [PMID: 19170546 DOI: 10.1021/jp808733p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
At 25 degrees C ultrasonic attenuation spectra between 100 kHz and 400 MHz as well as sound velocities and densities of aqueous solutions of the surfactant n-octyl-beta-d-glucopyranoside and of the cage compound alpha-cyclodextrin have been measured. The liquid system reveals a critical association concentration (cac) exceeding the cmc of the surfactant almost by the cyclodextrin concentration and thus indicating a significant formation of cyclodextrin-surfactant inclusion complexes. The ultrasonic spectra display altogether four relaxation regions. The one with largest relaxation time (0.27 mus < or = tau(1) < or = 1.6 mus) exhibits a noticeable amplitude at surfactant concentrations larger than the cac only. It is assigned to the monomer exchange between the micelles and the suspending phase. A term with relaxation time tau(2) (33 ns < or = tau(2) < or = 135 ns) is characteristic for solutions containing both solutes. It is assumed to reflect the inclusion complex formation. Complexes with 1:1, 2:1, and 1:2 stoichiometry appear to exist. The terms at higher frequencies (4.8 ns < or = tau(3) < or = 9.8 ns; 0.8 ns <or = tau(4) < or = 2 ns) are due to fluctuations of the carbohydrate residues around the glucosidic bond angles and to the rotational isomerization of the exocyclic hydroxymethyl groups, respectively.
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Affiliation(s)
- Julian Haller
- Drittes Physikalisches Institut, Georg-August-Universitat, Friedrich-Hund-Platz 1, 37077 Gottingen, Germany
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20
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Haller J, Kaatze U. Complexation versus micelle formation: α-Cyclodextrin+n-decyltrimethylammonium bromide aqueous solutions. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.08.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Shchekin AK, Kuni FM, Grinin AP, Rusanov AI. A kinetic description of the fast relaxation of coexisting spherical and cylindrical micelles. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2008. [DOI: 10.1134/s0036024408010159] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Polacek R, Kaatze U. Monomer Exchange Kinetics, Radial Diffusion, and Hydrocarbon Chain Isomerization of Sodium Dodecylsulfate Micelles in Water. J Phys Chem B 2007; 111:1625-31. [PMID: 17261063 DOI: 10.1021/jp066974g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molecular relaxation properties of sodium dodecylsulfate in aqueous solutions with surfactant concentrations between 0.009 and 0.4 mol/L have been studied using broadband ultrasonic spectrometry in the frequency range 0.1-2000 MHz. Ultrasonic excess attenuation characteristics were found that could be well represented by a sum of three relaxation terms, each one characterized by a discrete relaxation time. The low-frequency term with concentration-dependent relaxation time, tau1, between 0.06 and 3.5 micros is discussed in terms of the surfactant monomer exchange. The noticeable effect from the incomplete dissociation of the surfactant counter ions and the variation of the monomer concentration following thereby is discussed. The second relaxation term (0.9 <or= tau2 <or= 2.5 ns) is assigned to the limited radial diffusion of monomers within the micelles, yielding a mean diffusion length of 0.5 nm, in correspondence to protrusions by four methyl groups. The high-frequency relaxation term (0.1 <or= tau3 <or= 0.2 ns) reflects the structural isomerizations of the hydrocarbon chains in the micellar cores, largely resembling those of liquid alkanes.
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Affiliation(s)
- R Polacek
- Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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23
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Haller J, Behrends R, Kaatze U. Critical fluctuations of the micellar triethylene glycol monoheptyl ether-water system. J Chem Phys 2006; 124:124910. [PMID: 16599728 DOI: 10.1063/1.2179424] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using the equal volume criterion and also the pseudospinodal conception the critical demixing point of the triethylene glycol monoheptyl ether/water system (C7E3H2O) has been determined as Ycrit=0.1 and Tcrit=296.46 K (Y, mass fraction of surfactant). From density measurements the critical micelle concentration (cmc) followed as Ycmc=0.007 at 288.15 K and Ycmc=0.0066 at 298.15 K. The (static) shear viscosity etas and the mutual diffusion coefficient D of the C7E3H2O mixture of critical composition have been evaluated to yield their singular and background parts. From a combined treatment of both quantities the relaxation rate Gamma of order parameter fluctuations has been derived. Gamma follows power law with universal critical exponent and amplitude Gamma0=3.1 x 10(9) s(-1). Broadband ultrasonic spectra of C7E3H2O mixtures exhibit a noncritical relaxation, reflecting the monomer exchange between micelles and the suspending phase, and a critical term due to concentration fluctuations. The former is subject to a relaxation time distribution that broadens when approaching the critical temperature. The latter can be well represented with the aid of the dynamic scaling model by Bhattacharjee and Ferrell (BF) [Phys. Rev. A. 31, 1788 (1985)]. The half-attenuation frequency in the scaling function of the latter model is noticeably smaller (Omega12 (BF) approximately 1) than the theoretically predicted value Omega12 (BF)=2.1. This result has been taken as an indication of a coupling between the fluctuations in the local concentration and the kinetics of micelle formation, in correspondence with the idea of a fluctuation controlled monomer exchange [T. Telgmann and U. Kaatze, Langmuir 18, 3068 (2002)].
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Affiliation(s)
- J Haller
- Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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24
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Affiliation(s)
- Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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25
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Menzel K, Mirzaev SZ, Kaatze U. Crossover behavior in micellar solutions with lower critical demixing point: broadband ultrasonic spectrometry of the isobutoxyethanol-water system. PHYSICAL REVIEW E 2003; 68:011501. [PMID: 12935144 DOI: 10.1103/physreve.68.011501] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2003] [Indexed: 11/07/2022]
Abstract
The aggregation kinetics of isobutoxyethanol-water mixtures with lower critical demixing point has been investigated. Two types of kinetics have been observed, a diffusion-controlled formation of micellar species and the formation of a microheterogeneous liquid structure, governed by fluctuations in the local concentration. Ultrasonic attenuation spectra of isobutoxyethanol-water mixtures have been measured between 100 kHz and 2 GHz at 25 degrees C and at several concentrations, covering the complete composition range. With the mixture of critical composition measurements have been performed at some temperatures near the critical temperature (T(c)=299.51 K). In addition to the asymptotic high frequency background contribution, the broadband spectra reveal a Bhattacharjee-Ferrell relaxation term due to critical concentration fluctuations, a restricted Hill term reflecting the monomer exchange between micelles and the suspending phase, and two Debye-type relaxation terms that are assigned to chemical relaxations. The relaxation rates of the Bhattacharjee-Ferrell term exceed those from static and dynamic light scattering (amplitude Gamma(0)=5.3 x 10(9) s(-1)), likely due to the effect of a second parallel pathway of relaxation in the ultrasonic field. The adiabatic coupling constant following from the amplitude in the ultrasonic spectrum agrees with that from a thermodynamic relation (g=1.3). The restricted Hill term displays the features of an extended Teubner-Kahlweit-Aniansson-Wall model of the micelle formation and decay kinetics in surfactant solutions with high critical micelle concentration (C=0.6 mol/l). The idea of a fluctuation controlled monomer exchange in aqueous solutions of poly(ethylene glycol) monoalkyl ether-water mixtures near the critical point is briefly discussed.
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Affiliation(s)
- K Menzel
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, 37073 Göttingen, Germany
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Abstract
Previous studies on surfactant adsorption mostly deal with dilute systems without aggregation in the bulk phase. At the same time, micellar solutions can be more important from the point of view of applications. If one attempts to estimate the equilibrium adsorption, neglecting the influence of micelles can lead to reasonable results. The situation differs for non-equilibrium systems when the adsorption rate can increase by an order of magnitude at the increase of the surfactant concentration beyond the CMC. A critical survey of various models describing the influence of micelles on adsorption kinetics at the liquid-gas interface is given and the theoretical results are compared with existing experimental data. The theories proposed for the case of large deviations from the equilibrium are usually based on some unjustifiable assumptions and can describe the kinetic dependencies of adsorption in only a limited number of situations. Consequently, only rough estimates of the kinetic coefficients of micellization can be obtained from experimental data on dynamic surface tension. More rigorous equations can be derived if the system only deviates slightly from equilibrium. In the latter case, the agreement between theoretical and experimental results is essentially better and measurements of the dynamic surface elasticity of micellar solutions allow us to study the micellization kinetics.
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Affiliation(s)
- B A Noskov
- Research Institute of Chemistry, St. Petersburg State University, Russia.
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Abstract
Ultrasound is a technique that is capable of tremendous accuracy and precision, whether in the laboratory or on-line in the factory. Data acquisition rates of the order of kHz transform process monitoring, providing unprecedented information of high statistical value. Ultrasound is complementary to other measurement modalities, probing the elastic and thermal properties of materials. In the absence of air bubbles, ultrasound travels through concentrated systems of particles, providing information about size, compressibility, structure, distribution, chemical and phase state. It is safe, can be non-invasive and can be economical. In these respects, it is unique.
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Telgmann T, Kaatze U. Monomer Exchange and Concentration Fluctuations in Poly(ethylene glycol) Monoalkyl Ether/Water Mixtures. Dependence upon Nonionic Surfactant Composition. J Phys Chem A 2000. [DOI: 10.1021/jp994159d] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- T. Telgmann
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
| | - U. Kaatze
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
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Telgmann T, Kaatze U. Monomer Exchange and Concentration Fluctuations of Micelles. Broad-Band Ultrasonic Spectrometry of the System Triethylene Glycol Monohexyl Ether/Water. J Phys Chem A 2000. [DOI: 10.1021/jp9923116] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T. Telgmann
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
| | - U. Kaatze
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
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31
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De Maeyer L, Trachimow C, Kaatze U. Simulation Study to Model Extremely Slow Reaggregation Processes in Micelle Solutions. J Phys Chem B 1998. [DOI: 10.1021/jp982215p] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. De Maeyer
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg, D-37077 Göttingen, Germany, and Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
| | - C. Trachimow
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg, D-37077 Göttingen, Germany, and Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
| | - U. Kaatze
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg, D-37077 Göttingen, Germany, and Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
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33
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Telgmann T, Kaatze U. On the Kinetics of the Formation of Small Micelles. 2. Extension of the Model of Stepwise Association. J Phys Chem B 1997. [DOI: 10.1021/jp970748c] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T. Telgmann
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
| | - U. Kaatze
- Drittes Physikalisches Institut, Georg-August-Universität, Bürgerstrasse 42-44, D-37073 Göttingen, Germany
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