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Suman K, Mittal M, Joshi YM. Effect of sodium pyrophosphate and understanding microstructure of aqueous LAPONITE ® dispersion using dissolution study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:224002. [PMID: 32015220 DOI: 10.1088/1361-648x/ab724d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, we investigate the physical origin of ergodicity breaking in an aqueous colloidal dispersion of synthetic hectorite clay, LAPONITE®, by performing dissolution and rheological experiments with monovalent salt and tetrasodium pyrophosphate solution. We also study the effect of pH and nature of interface, nitrogen and paraffin oil on the same. Dissolution experiments carried out for dispersions with both the interfaces show similar results. However, for samples with a nitrogen interface, all the effects are observed to get expedited in time compared to a paraffin oil interface. When kept in contact with water, 1.5 wt.% and 2.8 wt.% colloidal dispersion at pH 10 swells at small ages, while it does not swell at large ages. The solution of tetrasodium pyrophosphate, interestingly, dissolves the entire colloidal dispersion sample with pH 10 irrespective of the concentration of clay. Experiments carried out on colloidal dispersions prepared in water having pH 13 demonstrate no effect of water as well as sodium pyrophosphate solution on the same suggesting a possibility of the presence of negative charge on edge at that pH. We believe that all the behaviors observed for samples at pH 10 can be explained by an attractive gel microstructure formed by edge-to-face contact. Furthermore, the absence of swelling in old colloidal dispersion at pH 10 and dissolution of the same by sodium pyrophosphate solution cannot be explained by merely repulsive interactions. This behavior suggests that attractive interactions originating from edge-to-face contact play an important role in causing ergodicity breaking in the colloidal dispersions at pH 10 at all the ages irrespective of the clay concentration. We further substantiate the presence of a fractal network structure formed by interparticle edge-face association using rheological tools and cryo-TEM imaging. We also conduct a comprehensive study of the effect of tetrasodium pyrophosphate on the sol-gel transition of LAPONITE® dispersion.
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Affiliation(s)
- Khushboo Suman
- Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
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2
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Ramphal IA, Hagerman ME. Nanoscale morphology, tribology and electrical properties of polyaniline/graphene oxide/LAPONITE® composites investigated using atomic force microscopy. NANOSCALE 2019; 11:20876-20883. [PMID: 31657821 DOI: 10.1039/c9nr05713g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polyaniline composites with graphene and graphene oxide have received broad interest for applications in charge separation and storage in electrical devices. Syntheses via in situ polymerization of aniline in colloidal dispersions of graphene oxide have afforded nanocomposites of polyaniline intercalated within graphene oxide nanosheets. The simultaneous inclusion of LAPONITE® nanoparticles has improved aqueous phase processability and thin film formation. Mechanical, morphological and conductivity studies including atomic force microscopy and scanning electron microscopy were employed to study the host-guest interactions and heterointerfaces that govern self-assembly. Adhesion and conductivity values within graphene oxide/polyaniline/LAPONITE® (GOPL) nanocomposites were tuned by varying the weight ratios of polyaniline : graphene oxide. These studies inform ongoing work to use GOPL nanomaterials for clean energy harvesting and storage applications.
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3
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Luo Z, Zhou J, Liu B. Engineering Surface Patterning of Colloidal Rings through Plateau-Rayleigh Instability. Angew Chem Int Ed Engl 2019; 58:16884-16888. [PMID: 31531921 DOI: 10.1002/anie.201910695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Indexed: 11/05/2022]
Abstract
Plateau-Rayleigh (P-R) instability occurring on Brownian colloidal particles is presented. This instability can be used for the surface patterning of Brownian colloidal rings. This idea was realized by employing polystyrene(PS)/SiO2 core/shell rings, for which PS layer was selectively grown onto the interior surface of SiO2 rings. The P-R instability was initiated in the ring's dispersion by adding a good solvent of PS. By using both experiments and theory, it is shown that the number of patches is tunable and that it is linearly related to a function of two variables, namely, solvent quantity and contact angle. In particular, one-patch Janus rings and patchy disks were also synthesized at high yields. The patch size of all particles is tunable by step-by-step polymerization and the patches can be functionalized, for example by ATRP grafting with pH-sensitive polymers. This approach can be adapted for the synthesis of other patchy colloids with designated complexity.
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Affiliation(s)
- Zhang Luo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100149, China
| | - Jiajia Zhou
- Center of Soft Matter Physics and Its Application, Beihang University, Beijing, 100191, China
| | - Bing Liu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100149, China
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4
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Luo Z, Zhou J, Liu B. Engineering Surface Patterning of Colloidal Rings through Plateau–Rayleigh Instability. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Zhang Luo
- Beijing National Laboratory for Molecular SciencesState Key Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100149 China
| | - Jiajia Zhou
- Center of Soft Matter Physics and Its ApplicationBeihang University Beijing 100191 China
| | - Bing Liu
- Beijing National Laboratory for Molecular SciencesState Key Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100149 China
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Germain P, Amokrane S. Glass transition and reversible gelation in asymmetric binary mixtures: A study by mode coupling theory and molecular dynamics. Phys Rev E 2019; 100:042614. [PMID: 31770885 DOI: 10.1103/physreve.100.042614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Indexed: 06/10/2023]
Abstract
The glass transition and the binodals of asymmetric binary mixtures are investigated from the effective fluid approach in the mode coupling theory and by molecular dynamics. Motivated by previous theoretical predictions, the hard-sphere mixture and the Asakura-Oosawa models are used to analyze experimental results from the literature, relative to polystyrene spheres mixed either with linear polymers or with dense microgel particles. In agreement with the experimental observations, the specificity of the depletant particles is shown to favor lower density gels. It further favors equilibrium gelation by reducing also the tendency of the system to phase separate. These results are confirmed by a phenomenological modification of the mode coupling theory in which the vertex functions are computed at an effective density lower than the actual one. A model effective potential in asymmetric mixtures of hard particles is used to further check this phenomenological modification against molecular dynamics simulation.
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Affiliation(s)
- Ph Germain
- Physique des Liquides et Milieux Complexes, Faculté des Sciences et Technologie, Université Paris Est (Créteil), 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France
| | - S Amokrane
- Physique des Liquides et Milieux Complexes, Faculté des Sciences et Technologie, Université Paris Est (Créteil), 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France
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6
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Suman K, Joshi YM. Microstructure and Soft Glassy Dynamics of an Aqueous Laponite Dispersion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:13079-13103. [PMID: 30180583 DOI: 10.1021/acs.langmuir.8b01830] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Synthetic hectorite clay Laponite RD/XLG is composed of disk-shaped nanoparticles that acquire dissimilar charges when suspended in an aqueous medium. Owing to their property to spontaneously self-assemble, Laponite is used as a rheology modifier in a variety of commercial water-based products. In particular, an aqueous dispersion of Laponite undergoes a liquid-to-solid transition at about 1 vol % concentration. The evolution of the physical properties as the dispersion transforms to the solid state is reminiscent of physical aging in molecular as well as colloidal glasses. The corresponding soft glassy dynamics of an aqueous Laponite dispersion, including the rheological behavior, has been extensively studied in the literature. In this feature article, we take an overview of recent advances in understanding soft glassy dynamics and various efforts taken to understand the peculiar rheological behavior. Furthermore, the continuously developing microstructure that is responsible for the eventual formation of a soft solid state that supports its own weight against gravity has also been a topic of intense debate and discussion. In particularly, extensive experimental and theoretical studies lead to two types of microstructures for this system: an attractive gel-like or a repulsive glass-like structure. We carefully examine and critically analyze the literature and propose a state (phase) diagram that suggests an aqueous Laponite dispersion to be present in an attractive gel state.
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Affiliation(s)
- Khushboo Suman
- Department of Chemical Engineering , Indian Institute of Technology Kanpur , India
| | - Yogesh M Joshi
- Department of Chemical Engineering , Indian Institute of Technology Kanpur , India
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Du M, Liu J, Clode PL, Leong YK. Surface chemistry, rheology and microstructure of purified natural and synthetic hectorite suspensions. Phys Chem Chem Phys 2018; 20:19221-19233. [PMID: 29987309 DOI: 10.1039/c8cp01382a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Natural (N-) and synthetic (S-) hectorite suspensions were found to display significant time-dependent rheology or ageing behaviour and shear thinning flow behaviour. The ageing behaviour was characterised by an increasing yield stress with rest time. The yield stress continued to increase even after a week of rest, a reflection of a long process. An open sponge-like cellular microstructure formed by platelet particles interacting attractively in the overlapping edge-face configuration was captured by cryo-SEM of gel samples prepared at high pressure (∼2000 bar) and subjected to rapid cryo-freezing, for both N- and S-hectorite gels. Even nano-discotic S-hectorite particles formed platelet particles hundreds of nanometres in length in the overlapping coin configuration. This structure, displaying a cell size ranging from tens to several hundred nanometres, is formed by strong attractive and repulsive forces. The platelets showed deformations such as bending and curling of the edges in response to these forces. The S-hectorite platelets are smaller and more rigid. During ageing the particles in the structure experience a net force. These particles will move in response causing force imbalance to be experienced by neighbouring particles and they will move in response. This action and reaction percolate through the network structure causing a high concentration of particles to respond. As a consequence the ageing process takes a long time to reach equilibrium. Various ageing models were used to fit the ageing data. The N-hectorite gels displayed a maximum yield stress at pH ∼ 8 and a particle zeta potential of -35 mV. This suggests the presence of critical positive and negative charge density is needed to form a structure with maximum strength. The zeta potential is negative and quite insensitive to pH from pH 4 to 12.
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Affiliation(s)
- Mingyong Du
- Department of Chemical Engineering, The University of Western Australia, Perth 6009, Australia.
| | - Jishan Liu
- Department of Chemical Engineering, The University of Western Australia, Perth 6009, Australia.
| | - Peta L Clode
- Centre for Microscopy, Characterization and Analysis, The University of Western Australia, Perth 6009, Australia
| | - Yee-Kwong Leong
- Department of Chemical Engineering, The University of Western Australia, Perth 6009, Australia.
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8
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Marques FADM, Angelini R, Ruocco G, Ruzicka B. Isotopic Effect on the Gel and Glass Formation of a Charged Colloidal Clay: Laponite. J Phys Chem B 2017; 121:4576-4582. [PMID: 28376301 DOI: 10.1021/acs.jpcb.6b12596] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The time evolution of both dynamic and static structure factors of a charged colloidal clay, Laponite, dispersed in both H2O and D2O solvents has been investigated through multiangle dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) as a function of weight concentration. The aging phenomenology and the formation of arrested states, both gel and glass, are preserved in D2O, while the dynamics is slowed down with respect to water. These findings are important to understand the role played by the solvent in the interparticle interactions and for techniques such as neutron scattering and nuclear magnetic resonance that allow for the extension of the accessible scattering vectors and time scales.
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Affiliation(s)
| | - Roberta Angelini
- ISC-CNR, Sede Sapienza , I-00185 Roma, Italy.,Dipartimento di Fisica, Sapienza Università di Roma , I-00185 Roma, Italy
| | - Giancarlo Ruocco
- Dipartimento di Fisica, Sapienza Università di Roma , I-00185 Roma, Italy.,Center for Life Nano Science, IIT@Sapienza, Istituto Italiano di Tecnologia , Viale Regina Elena 291, 00161 Roma, Italy
| | - Barbara Ruzicka
- ISC-CNR, Sede Sapienza , I-00185 Roma, Italy.,Dipartimento di Fisica, Sapienza Università di Roma , I-00185 Roma, Italy
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9
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Rheological inversion of the universal aging dynamics of hectorite clay suspensions. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2015.11.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Jatav S, Joshi YM. Analyzing a fractal gel of charged oblate nanoparticles in a suspension using time-resolved rheometry and DLVO theory. Faraday Discuss 2016; 186:199-213. [DOI: 10.1039/c5fd00128e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The disk-like nanoparticles of LAPONITE® are known to self-assemble to form a fractal gel within hours after a sufficiently large concentration of LAPONITE® is dispersed in water containing salt. The concentration of sodium counterions associated with LAPONITE® particles, however, continues to increase over a period of days, suggesting that delamination of LAPONITE® disks from stacks is sluggish and/or dissociation of counterions is slow. In either case, spontaneous self-assembly of LAPONITE® particles occurs even though delamination and/or counterion dissociation has not reached its equilibrium state. In order to determine the nature of the fractal gel as the extent of delamination and/or dissociation progresses towards equilibrium, we subject the LAPONITE® suspension to a freezing–defrosting cycle, which interestingly reinitiates the gelation process in suspension afresh. Application of time-resolved rheometry to a defrosted suspension shows that iso-frequency loss tangent curves intersect at an identical point, validating the Winter–Chambon criterion for a critical fractal gel state. Interestingly, while the time required to form a critical gel is observed to decrease with increased time elapsed since preparation, at which freezing–defrosting is carried out, the fractal dimension of the critical gel is observed to remain unaffected. We also solve DLVO theory for free energy interactions between the negatively charged LAPONITE® particle faces and analyze the observed phenomena.
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Affiliation(s)
- Shweta Jatav
- Department of Chemical Engineering
- Indian Institute of Technology, Kanpur
- Kanpur-208016
- India
| | - Yogesh M. Joshi
- Department of Chemical Engineering
- Indian Institute of Technology, Kanpur
- Kanpur-208016
- India
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11
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12
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Shu R, Sun W, Liu X, Tong Z. Temperature dependence of aging kinetics of hectorite clay suspensions. J Colloid Interface Sci 2015; 444:132-40. [PMID: 25594804 DOI: 10.1016/j.jcis.2014.12.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 12/11/2014] [Accepted: 12/20/2014] [Indexed: 10/24/2022]
Abstract
The aging of salt-free hectorite suspensions with different concentrations (c(L)=2.9, 3.2 and 3.5 wt%) stored for 2 days or 4 days was studied by rheology at different temperatures. The evolution of storage and loss moduli G' and G″ during aging followed aging time-temperature superposition. The temperature dependence of the shift factor a(T), which reflected the aging kinetics, was interpreted by the reaction-limited colloidal aggregation (RLCA) mechanism with counterion condensation in calculating the double-layer interaction of the charged clay particles. Temperature dependence of the plateau modulus and yield stress of the suspension aged for 800 s was modeled with the soft glassy rheology (SGR) theory. The estimated noise temperature x indicated that the sample aged at higher temperature corresponded to a deeper quench in the nonergodic state. Under larger amplitude of oscillatory shear, the suspension exhibited a strain rate-frequency superposition (SRFS). The shearing eliminated the effects of aging and heating.
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Affiliation(s)
- Ruiwen Shu
- Research Institute of Materials Science and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Weixiang Sun
- Research Institute of Materials Science and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Xinxing Liu
- Research Institute of Materials Science and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Zhen Tong
- Research Institute of Materials Science and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China.
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13
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Saha D, Bandyopadhyay R, Joshi YM. Dynamic light scattering study and DLVO analysis of physicochemical interactions in colloidal suspensions of charged disks. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3012-3020. [PMID: 25726709 DOI: 10.1021/acs.langmuir.5b00291] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interparticle interactions in colloidal suspensions of charged disks of Laponite clay in water were investigated using dynamic light scattering (DLS) and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We studied the effects of clay concentration (C(L)), the concentration of externally added salt (C(S)), and temperature (T) on the microscopic dynamics of the clay suspensions. The fast (τ1) and mean slow relaxation times (⟨τ(ww)⟩) of Laponite suspensions were extracted from intensity autocorrelation functions measured at different waiting times (t(w)) after sample preparation. Comprehensive Laponite concentration-salt concentration-temperature-time superpositions of both the microscopic diffusive time scales and the stretching exponent corresponding to the slow relaxation process highlight the self-similar nature of the energy landscapes of the Laponite suspensions. The evolution of the sodium ion concentration in the aging suspension with tw, measured for several values of CL, CS, and T, was used in a DLVO analysis of the free energy of the suspension for two charged disks parallely approaching one another. This analysis confirms that, in addition to repulsive interparticle interactions, attractive interactions also play a pivotal role in the microscopic dynamics of spontaneously evolving Laponite suspensions.
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Affiliation(s)
- Debasish Saha
- †Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India
| | - Ranjini Bandyopadhyay
- †Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India
| | - Yogesh M Joshi
- ‡Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016, India
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Ndong Mintsa E, Germain P, Amokrane S. Bond lifetime and diffusion coefficient in colloids with short-range interactions. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:21. [PMID: 25813606 DOI: 10.1140/epje/i2015-15021-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 06/04/2023]
Abstract
We use molecular dynamics simulations to study the influence of short-range structures in the interaction potential between hard-sphere-like colloidal particles. Starting from model potentials and effective potentials in binary mixtures computed from the Ornstein-Zernike equations, we investigate the influence of the range and strength of a possible tail beyond the usual core repulsion or the presence of repulsive barriers. The diffusion coefficient and mean "bond" lifetimes are used as indicators of the effect of this structure on the dynamics. The existence of correlations between the variations of these quantities with the physical parameters is discussed to assess the interpretation of dynamics slowing down in terms of long-lived bonds. We also discuss the question of a universal behaviour determined by the second virial coefficient B ((2)) and the interplay of attraction and repulsion. While the diffusion coefficient follows the B ((2)) law for purely attractive tails, this is no longer true in the presence of repulsive barriers. Furthermore, the bond lifetime shows a dependence on the physical parameters that differs from that of the diffusion coefficient. This raises the question of the precise role of bonds on the dynamics slowing down in colloidal gels.
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Affiliation(s)
- E Ndong Mintsa
- Laboratoire "Physique de Liquides et Milieux Complexes", Faculté des Sciences et Technologie, Université Paris-Est, Créteil, 61 avenue du Général de Gaulle, 94010, Créteil Cedex, France
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15
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Tudisca V, Bruni F, Scoppola E, Angelini R, Ruzicka B, Zulian L, Soper AK, Ricci MA. Neutron diffraction study of aqueous Laponite suspensions at the NIMROD diffractometer. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032301. [PMID: 25314440 DOI: 10.1103/physreve.90.032301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Indexed: 06/04/2023]
Abstract
The process of dynamical arrest, leading to formation of different arrested states such as glasses and gels, along with the closely related process of aging, is central for both basic research and technology. Here we report on a study of the time-dependent structural evolution of two aqueous Laponite clay suspensions at different weight concentrations. Neutron diffraction experiments have been performed with the near and intermediate range order diffractometer (NIMROD) that allows studies of the structure of liquids and disordered materials over a continuous length scale ranging from 1 to 300 Å, i.e., from the atomistic to the mesoscopic scales. NIMROD is presently a unique diffractometer, bridging the length scales traditionally investigated by small angle neutron scattering or small angle x-ray scattering with that accessible by traditional diffractometers for liquids. Interestingly, we have unveiled a signature of aging of both suspensions in the length scale region of NIMROD. This phenomenon, ascribed to sporadic contacts between Laponite platelets at long times, has been observed with the sample arrested as gel or as repulsive glass. Moreover, water molecules within the layers closest to Laponite platelets surface show orientational and translational order, which maps into the crystalline structure of Laponite.
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Affiliation(s)
- V Tudisca
- Dipartimento di Scienze, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
| | - F Bruni
- Dipartimento di Scienze, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
| | - E Scoppola
- Dipartimento di Scienze, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
| | - R Angelini
- IPCF-CNR and Dipartimento di Fisica, Università di Roma "La Sapienza", Piazzale A. Moro 2, I-00185, Rome, Italy
| | - B Ruzicka
- IPCF-CNR and Dipartimento di Fisica, Università di Roma "La Sapienza", Piazzale A. Moro 2, I-00185, Rome, Italy
| | - L Zulian
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano Bicocca, Via Roberto Cozzi, 53 20125 Milano, Italy
| | - A K Soper
- ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, OX11 0QX, United Kingdom
| | - M A Ricci
- Dipartimento di Scienze, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
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16
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Klajner P, Kaloun S, Münch JP, Hébraud P. Restricted diffusion of small probe particles in a laponite dispersion. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:032308. [PMID: 24125269 DOI: 10.1103/physreve.88.032308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Indexed: 06/02/2023]
Abstract
Evanescent wave microscopy is used to study the dynamics of probe particles inside a laponite suspension, when the size of the latex probes is of the order of the diameter of the laponite disks. A correlation procedure is introduced that allows us to study quantitatively the diffusion of small probes. For all studied sizes, the motion exhibits two modes: a fast relaxation mode and a slow relaxation mode. In the fast relaxation mode, the probes diffuse in a viscous medium, whose viscosity does not depend on the diameter of the probes and is slightly larger than the viscosity of water. Then, the diffusion of the particles is restricted over distances larger than their diameters, which increase when the particle diameter decreases. In this regime, the probe particles experience the elasticity of the solution and the apparent elastic modulus increases when the diameter of the probe particle increases, whereas for large enough particles, the macroscopic behavior is recovered, in which the diffusing particles experience a homogeneous medium, and the macroscopic elastic modulus is recovered.
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Affiliation(s)
- P Klajner
- IPCMS/CNRS, 23 rue du Loess, 67034 Strasbourg, France
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17
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Shahin A, Joshi YM. Physicochemical effects in aging aqueous Laponite suspensions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15674-15686. [PMID: 23057660 DOI: 10.1021/la302544y] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study aging behavior of an aqueous suspension of Laponite as a function of concentration of Laponite, concentration of salt, time elapsed since preparation of suspension (idle time), and temperature by carrying extensive rheological and conductivity experiments. We observe that temporal evolution of elastic moduli, which describes structural build-up and aging, shifts to low times for experiments carried out for higher concentration of Laponite, higher concentration of salt, greater temperature, and longer idle time while preserving the curvature of evolution in the solid regime (elastic modulus greater than viscous modulus). Consequently appropriate shifting of evolution of elastic modulus in the solid regime leads to aging time-idle time-salt concentration-Laponite concentration-temperature superposition. The existence of such a superposition suggests the generic nature of microstructure buildup irrespective of mentioned variables in the explored range. The behavior of shift factors needed to obtain the superposition indicate that the energy barrier associated with structural buildup decreases with an increase in idle time and temperature and decreases linearly with an increase in concentration of Laponite and that of salt. The conductivity experiments show that ionic conductivity of the suspension increases with increasing Laponite concentration, salt concentration, temperature, and very importantly the idle time. We also analyze the interparticle interactions using DLVO theory that suggests an increase in idle time, temperature, and salt concentration increases the height of the repulsive energy barrier while it decreases the width of the same when particles approach each other in a parallel fashion. However when particles approach each other in a perpendicular fashion, owing to dissimilar charges on edge and face, the energy barrier for the attractive interaction is expected to decrease with an increase in idle time, temperature, and salt concentration. Analysis of rheological and conductivity experiments suggests a strong influence of attractive interactions on the low energy structures in an aqueous suspension of Laponite.
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Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, India
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18
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Jabbari-Farouji S, Wegdam GH, Bonn D. Aging of rotational diffusion in colloidal gels and glasses. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:041401. [PMID: 23214583 DOI: 10.1103/physreve.86.041401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Indexed: 06/01/2023]
Abstract
We study the rotational diffusion of aging Laponite suspensions for a wide range of concentrations using depolarized dynamic light scattering. The measured orientational correlation functions undergo an ergodic to nonergodic transition that is characterized by a concentration-dependent ergodicity-breaking time. We find that the relaxation times associated with rotational degree of freedom as a function of waiting time, when scaled with their ergodicity-breaking time, collapse on two distinct master curves. These master curves are similar to those previously found for the translational dynamics; the two different classes of behavior were attributed to colloidal gels and glasses. Therefore, the aging dynamics of rotational degree of freedom provides another signature of the distinct dynamical behavior of colloidal gels and glasses.
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Affiliation(s)
- S Jabbari-Farouji
- LPTMS, CNRS and Université Paris-Sud, UMR8626, Bat. 100, 91405 Orsay, France
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19
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Sun W, Yang Y, Wang T, Huang H, Liu X, Tong Z. Effect of adsorbed poly(ethylene glycol) on the gelation evolution of Laponite suspensions: Aging time-polymer concentration superposition. J Colloid Interface Sci 2012; 376:76-82. [DOI: 10.1016/j.jcis.2012.01.064] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/06/2011] [Accepted: 01/10/2012] [Indexed: 11/26/2022]
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20
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Shahin A, Joshi YM. Hyper-aging dynamics of nanoclay suspension. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5826-5833. [PMID: 22414339 DOI: 10.1021/la205153b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Aqueous suspension of nanoclay Laponite undergoes structural evolution as a function of time, which enhances its elasticity and relaxation time. In this work, we employ an effective time approach to investigate long-term relaxation dynamics by carrying out creep experiments. Typically, we observe that the monotonic evolution of elastic modulus shifts to lower aging times, while maxima in viscous moduli get progressively broader for experiments carried out on a later date after preparation (idle time) of the nanoclay suspension. Application of effective time theory produces a superposition of all the creep curves irrespective of their initial state. The resulting dependence of the relaxation time on aging time shows very strong hyper-aging dynamics at short idle times, which progressively weakens to demonstrate a linear dependence in the limit of very long idle times. Remarkably, this behavior of nanoclay suspensions is akin to that observed for polymeric glasses. Consideration of aging as a first-order process suggests that continued hyper-aging dynamics causes cessation of aging. The dependence of relaxation time on aging time, therefore, must attenuate eventually producing linear or weaker dependence on time in order to approach a progressively low-energy state in the limit of very long times as observed experimentally. We also develop a simple scaling model based on a concept of aging of an energy well, which qualitatively captures various experimental observations very well, leading to profound insight into the hyper-aging dynamics of nanoclay suspensions.
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Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur, India
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Majumdar S, Sood AK. Statistical properties of entropy-consuming fluctuations in jammed states of laponite suspensions: Fluctuation relations and generalized Gumbel distribution. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041404. [PMID: 22680472 DOI: 10.1103/physreve.85.041404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Revised: 12/04/2011] [Indexed: 06/01/2023]
Abstract
We report a universal large deviation behavior of spatially averaged global injected power just before the rejuvenation of the jammed state formed by an aging suspension of laponite clay under an applied stress. The probability distribution function (PDF) of these entropy consuming strongly non-Gaussian fluctuations follow an universal large deviation functional form described by the generalized Gumbel (GG) distribution like many other equilibrium and nonequilibrium systems with high degree of correlations but do not obey the Gallavotti-Cohen steady-state fluctuation relation (SSFR). However, far from the unjamming transition (for smaller applied stresses) SSFR is satisfied for both Gaussian as well as non-Gaussian PDF. The observed slow variation of the mean shear rate with system size supports a recent theoretical prediction for observing GG distribution.
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Affiliation(s)
- Sayantan Majumdar
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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22
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Tudisca V, Ricci MA, Angelini R, Ruzicka B. Isotopic effect on the aging dynamics of a charged colloidal system. RSC Adv 2012. [DOI: 10.1039/c2ra21486e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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23
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Shahin A, Joshi YM, Ramakrishna SA. Interface-induced anisotropy and the nematic glass/gel state in jammed aqueous Laponite suspensions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14045-14052. [PMID: 21995523 DOI: 10.1021/la202398v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Aqueous suspensions of Laponite, a system composed of disklike nanoparticles, are found to develop optical birefringence over several days, well after the suspensions solidified because of jamming. The optical anisotropy is particularly enhanced near the air-Laponite suspension interface over length scales of several millimeters, which is beyond 5 orders of magnitude larger than the particle length scale, suggestive of large-scale ordering influenced by the interface. The orientational order increases with time and is always greater for higher concentration of salt, higher concentration of Laponite, and higher temperatures of the suspension. Although weakly birefringent, Laponite suspensions covered by paraffin oil do not show any enhancement in optical anisotropy near the interface compared to that in the bulk. We suggest that the expedited structure formation near the air interface propagating progressively inside the sample is responsible for the observed behavior. We discuss the observed nematic ordering in the context of glass-like and gel-like microstructure associated with aqueous Laponite suspensions.
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Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
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24
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Unified scaling behavior of physical properties of clays in alcohol solutions. J Colloid Interface Sci 2011; 364:311-6. [DOI: 10.1016/j.jcis.2011.08.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/19/2011] [Accepted: 08/20/2011] [Indexed: 11/22/2022]
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25
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Yuan CN, Li YF, Sheng YJ, Tsao HK. Wet nanogranular materials: Colloidal glass and gel. J Chem Phys 2011; 135:174703. [DOI: 10.1063/1.3658501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Pujala RK, Pawar N, Bohidar HB. Landau theory description of observed isotropic to anisotropic phase transition in mixed clay gels. J Chem Phys 2011; 134:194904. [PMID: 21599085 DOI: 10.1063/1.3590028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A characteristic new cooperative dehydration transition, in 1:1 Laponite-MMT cogel, was observed at T(c) ≈ 60 °C, a temperature at which the storage modulus (G(')) and depolarization ratio (D(p)) showed sharp increase, and the isotropic cogel turned into an anisotropic one. The dehydration dynamics could be described through power-law relations: G(') ∼ (T(c)-T)(-γ) and D(p) ∼ (T(c)-T)(-β) with γ ≈ β = 0.40 ± 0.05. The x-ray diffraction data revealed that the crystallite size decreased from 17 nm (at 20 °C) to 10 nm (at 80 °C) implying loss of free and inter-planar water. When this cogel was spontaneously cooled below T(c), it exhibited much larger storage modulii values which implied the existence of several metastable states in this system. This phase transition could be modeled through Landau theory, where the depolarization ratio was used as experimental order parameter (ψ). This parameter was found to scale with temperature, as ψ ∼ (T(c)-T)(-α), with power-law exponent α = 0.40 ± 0.05; interestingly, we found α ≈ β ≈ γ.
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Affiliation(s)
- Ravi Kumar Pujala
- Nanomaterials and Nanocomposite Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067, India
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27
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Pujala RK, Pawar N, Bohidar HB. Universal sol state behavior and gelation kinetics in mixed clay dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5193-5203. [PMID: 21466239 DOI: 10.1021/la1048453] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Sol and gel state behavior, in aqueous salt free dispersions, of clays Laponite (L) and Na montmorillonite (MMT) was studied at various mixing ratios (L:MMT = r = 1:0.5, 1:1, and 1:2). In the sol state, the zeta potential and gelation concentration of L-MMT obeyed the universal relation, X(L-MMT) = (rX(L) + X(MMT))/(1 + r), where X is zeta potential or gelation concentration (c(g)), implying that these properties are linear combinations of the same of their individual components. The low frequency storage modulus (G(0)'), relative viscosity (η(r)), and apparent cluster size (R) could be universally described by the power-law, G(0)' ∼ ((c/c(g)) - 1)(t) (c > c(g)), and η(r), R ∼ (1 - (c/c(g)))(-k,ν) (c < c(g)), with t = 1.5, k = 1.1, and υ = 0.8 close to the gelation concentration, for r = 1:1 cogel, consistent with the percolation model description of gelation. Interestingly, the hyperscaling relation δ = t/(k + t) yielded δ = 0.56 not too different from the predicted value ∼0.7, while the experimental value of δ obtained from G''(ω) ∼ ω(δ) close to c ≈ c(g) yielded δ = 1.5, which was at variance with the hyperscaling result. The experimental data, on hand, mostly supported percolation type gelation mechanism. As the cogels were slowly heated, at a characteristic temperature, T(g), a sharp increase in G' value was noticed, implying a transition to gel hardening (a new phase state). The temperature-dependent behavior followed the power-law description, G' ∼ (T(g) - T)(-γ) (T < T(g)), with γ = 0.40 ± 0.05 invariant of composition of the cogel, whereas for MMT and Laponite, γ = 0.25 and 0.55, respectively. It has been shown that the cogel has significantly enhanced mechanical (G(0) increased by 10 times for r = 1:1 cogel) and thermal properties (T(g) increased by 13 °C for 1:1 cogel) that can be exploited to design customized soft materials.
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Affiliation(s)
- Ravi Kumar Pujala
- Nanomaterials and Nanocomposite Laboratory School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067, India
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28
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Zanchetta G, Cerbino R. Exploring soft matter with x-rays: from the discovery of the DNA structure to the challenges of free electron lasers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:323102. [PMID: 21386476 DOI: 10.1088/0953-8984/22/32/323102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
X-rays have long been a precious tool for the study of the structure of matter. While the short wavelength makes them ideal for investigating materials down to the atomic scale, their high penetration power allows for the exploration of opaque samples at a multitude of length scales. We give an overview of the x-ray techniques suited for the characterization of soft matter and of their application to systems of current interest. We describe the advantages and limitations of existing x-ray methods and outline the possible developments following the introduction of a new kind of coherent source: the x-ray free electron laser.
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Affiliation(s)
- Giuliano Zanchetta
- Dipartimento di Chimica, Biochimica e Biotecnologie per la Medicina, Università degli Studi di Milano, I-20133, Milano, Italy.
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29
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Plazanet M, Bartolini P, Sangregorio C, Taschin A, Torre R, Trommsdorff HP. Inverse freezing in molecular binary mixtures of alpha-cyclodextrin and 4-methylpyridine. Phys Chem Chem Phys 2010; 12:7026-31. [PMID: 20464011 DOI: 10.1039/b923682a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ternary solutions of alpha-cyclodextrin (alphaCD) in 4-methylpyridine (4MP)/water mixtures solidify when heated and melt when cooled, and the crystalline solid phase exhibits a rich phase behavior as a function of temperature. In this work, we extend these earlier investigations to pure binary mixtures of alphaCD in water free 4MP, characterized via temperature and time dependent measurements of viscosity, X-ray diffraction, and infrared spectroscopy, complemented by observations of acoustic properties and small angle neutron diffraction. At high concentrations (>500 g l(-1)), these solutions enter an amorphous solid phase not only with decreasing but also with increasing temperature, before crystallizing at higher temperatures. This inverse solidification is attributed to the growth of hydrogen bonded clusters, leading to a steep increase of the viscosity with temperature.
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Affiliation(s)
- Marie Plazanet
- European Laboratory for Non-Linear Spectroscopy (LENS), Universita di Firenze, Via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy.
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30
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Shayeganfar F, Jabbari-Farouji S, Movahed MS, Jafari GR, Tabar MRR. Stochastic qualifier of gel and glass transitions in laponite suspensions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:061404. [PMID: 20866418 DOI: 10.1103/physreve.81.061404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 04/27/2010] [Indexed: 05/29/2023]
Abstract
The existence of the important similarities between gelation and glass transition makes it hard to distinguish between the two types of nonergodic states experimentally. Here, we report on a stochastic analysis of the scattered light intensity through a colloidal particles suspension during the gel and glass formation. In this analysis, we exploit the methods developed for complex hierarchical systems, such as turbulence. Using the multiplicative log-normal cascade models, we provide a criterion to distinguish gels from glasses.
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Affiliation(s)
- F Shayeganfar
- Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran, Iran
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31
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Porion P, Faugère AM, Michot LJ, Paineau E, Delville A. Orientational microdynamics and magnetic-field-induced ordering of clay platelets detected by 2H NMR spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7035-7044. [PMID: 20047274 DOI: 10.1021/la904298d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The orientation of montmorillonite clays induced by a static magnetic field is quantified by using (2)H NMR spectroscopy. Indeed, the residual quadrupolar splitting of the (2)H resonance line measured for heavy water is a direct consequence of the specific orientation of the clay platelets in the static magnetic field. In the dilute regime, this residual splitting increases linearly with clay concentration, which confirms that the clay/clay electrostatic repulsions remain negligible by comparison with the diamagnetic coupling of these anisotropic platelets. At higher concentration, the electrostatic repulsion between clay particles markedly enhances the detected splitting. Such enhancement is well predicted by numerical simulations. By varying the size of the clay platelets and the strength of the static magnetic field, it is possible to evaluate the order of magnitude of the diamagnetic susceptibility of these anisotropic colloids.
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Affiliation(s)
- Patrice Porion
- Centre de Recherche sur la Matière Divisée, CNRS-Université d'Orléans, UMR6619, 45071 Orléans Cedex 02, France.
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32
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Russo J, Sciortino F. How do self-assembling polymers and gels age compared to glasses? PHYSICAL REVIEW LETTERS 2010; 104:195701. [PMID: 20866977 DOI: 10.1103/physrevlett.104.195701] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/10/2009] [Indexed: 05/29/2023]
Abstract
Experiments on gels have provided contradictory results concerning the relation between correlation and response functions during aging. To clarify this puzzle, we numerically investigate the fluctuation-dissipation plot in equilibrium polymers and in network forming gels employing two distinct observables, (i) the density Fourier transform and (ii) the single-particle potential energy, to probe (i) diffusional processes and (ii) the development of a bond network. The plot behaves very differently for the two cases. Violation from the equilibrium behavior is found only for the second observable. The experimental implications of the discovered sensitivity to the choice of the probe are discussed, in particular, with respect to the existing experimental results.
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Affiliation(s)
- John Russo
- Dipartimento di Fisica and CNR-ISC, Sapienza-Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
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33
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Miyamoto N, Iijima H, Ohkubo H, Yamauchi Y. Liquid crystal phases in the aqueous colloids of size-controlled fluorinated layered clay mineral nanosheets. Chem Commun (Camb) 2010; 46:4166-8. [PMID: 20454743 DOI: 10.1039/b927335b] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Size-controlled nanosheet colloids of fluorohectorite and fluortetrasilicic mica were prepared in high yield and their transitions to fluid liquid crystal (LC) phases with highly ordered lamellar structures were identified over a wide concentration range, which is a rare case for clay mineral systems.
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Affiliation(s)
- Nobuyoshi Miyamoto
- Department of Life, Environment and Materials Science, Fukuoka Institute of Technology, 3-30-1 Wajiro-Higashi, Higashi-ku, Fukuoka 811-0295, Japan.
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34
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Shahin A, Joshi YM. Irreversible aging dynamics and generic phase behavior of aqueous suspensions of Laponite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4219-4225. [PMID: 20099829 DOI: 10.1021/la9032749] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We study the aging behavior of aqueous suspension of Laponite having 2.8 wt % concentration using rheological tools. At various salt concentration all the samples demonstrate orientational order when observed using crossed polarizers. In rheological experiments we observe inherent irreversibility in the aging dynamics which forces the system not to rejuvenate to the same state in the shear melting experiment carried out at a later date since preparation. The extensive rheological experiments carried out as a function of time elapsed since preparation demonstrate the self-similar trend in the aging behavior irrespective of the concentration of salt. We observe that the exploration of the low-energy states as a function of aging time is only kinetically affected by the presence of salt. We estimate that the energy barrier to attain the low-energy states decreases linearly with increase in the concentration of salt. The observed superposition of all the elapsed time and the salt-concentration-dependent data suggests that the aging that occurs in low salt concentration systems over a very long period is qualitatively similar to the aging behavior observed in systems with high salt concentration over a shorter period.
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Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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35
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Ruzicka B, Zulian L, Zaccarelli E, Angelini R, Sztucki M, Moussaïd A, Ruocco G. Competing interactions in arrested States of colloidal clays. PHYSICAL REVIEW LETTERS 2010; 104:085701. [PMID: 20366947 DOI: 10.1103/physrevlett.104.085701] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Indexed: 05/29/2023]
Abstract
Using experiments, theory and simulations, we show that the arrested state observed in a colloidal clay at high concentrations is stabilized by screened Coulomb repulsion (Wigner glass). Dilution experiments allow us to distinguish this disconnected state, which melts upon addition of water, from a low-concentration gel state, which does not melt. Theoretical modeling and simulations at high concentrations reproduce the measured small angle x-ray scattering static structure factors and confirm the long-range electrostatic nature of the arrested structure. These findings are attributed to the different time scales controlling the competing attractive and repulsive interactions.
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Affiliation(s)
- B Ruzicka
- SOFT INFM-CNR and Dipartimento di Fisica, Sapienza Università di Roma, I-00185, Italy
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36
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Germain P, Amokrane S. Gelation and phase coexistence in colloidal suspensions with short-range forces: generic behavior versus specificity. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:011407. [PMID: 20365373 DOI: 10.1103/physreve.81.011407] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 08/31/2009] [Indexed: 05/29/2023]
Abstract
The interplay between physical gelation and equilibrium phase transitions in asymmetric binary mixtures is analyzed from the effective fluid approach, in which the big particles interact via a short-range effective attraction beyond the core due to the depletion mechanism. The question of the universality of the scenario for dynamical arrest is then addressed. The comparison of the phase diagrams of the hard-sphere mixture and the Asakura-Oosawa models at various size ratios shows that strong specificity is observed for nonideal depletants. In particular, equilibrium gelation, without the competition with fluid-fluid transition is possible in mixtures of hard-sphere colloids. This is interpreted from the specificities of the effective potential, such as its oscillatory behavior and its complex variation with the physical parameters. The consequences on the dynamical arrest and the fluid-fluid transition are then investigated by considering in particular the role of the well at contact and the first repulsive barrier. This is done for the actual effective potential in the hard-sphere mixture and for a square well and shoulder model, which allows a separate discussion of the role of the different parameters, in particular on the localization length and the escape time. This study is next extended to mixtures of "hard-sphere-like" colloids with residual interactions. It confirms the trends relative to equilibrium gelation and illustrates a diversity of the phase behavior well beyond the scenarios expected from simple models.
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Affiliation(s)
- Ph Germain
- Physique des Liquides et Milieux Complexes, Faculté des Sciences et Technologie, Université Paris Est (Créteil), Créteil Cedex, France
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37
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Shukla A, Joshi YM. Ageing under oscillatory stress: Role of energy barrier distribution in thixotropic materials. Chem Eng Sci 2009. [DOI: 10.1016/j.ces.2009.03.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Joshi YM. Modeling Dependence of Creep Recovery Behavior on Relaxation Time Distribution of Aging Colloidal Suspensions. Ind Eng Chem Res 2009. [DOI: 10.1021/ie801894z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yogesh M. Joshi
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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39
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Germain P, Amokrane S. Equilibrium route to colloidal gelation: mixtures of hard-sphere-like colloids. PHYSICAL REVIEW LETTERS 2009; 102:058301. [PMID: 19257564 DOI: 10.1103/physrevlett.102.058301] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Indexed: 05/27/2023]
Abstract
The binodals and the nonergodicity lines of a binary mixture of hard-sphere-like particles with a large size ratio are computed for studying the interplay between dynamic arrest and phase separation in depletion-driven colloidal mixtures. Contrary to the case of hard core plus short-range effective attraction, physical gelation without competition with the fluid-phase separation can occur in such mixtures. This behavior due to the oscillations in the depletion potential should concern all simple mixtures with a nonideal depletant, justifying further studies of their dynamic properties.
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Affiliation(s)
- Ph Germain
- Laboratoire de Physique des Liquides et Milieux Complexes, Faculté des Sciences et Technologie, Université Paris Est (Créteil), 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France
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40
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Fonseca DM, Méheust Y, Fossum JO, Knudsen KD, Parmar KPS. Phase diagram of polydisperse Na-fluorohectorite-water suspensions: a synchrotron small-angle x-ray scattering study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:021402. [PMID: 19391742 DOI: 10.1103/physreve.79.021402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Indexed: 05/27/2023]
Abstract
Systems of platelet-shaped nanostacks of the synthetic clay Na-fluorohectorite, suspended in saline solutions of various salt concentrations, exhibit a rich phase behavior with up to four phases coexisting in a single sample tube. They are studied here using small-angle x-ray scattering: the anisotropy of the obtained images is quantified, and, together with x-ray absorption measurements, this provides a precise determination of the phase boundaries, as well as a measure of the orientational ordering of the clay colloids in the various gel phases. The coexistence of different phases results from a sedimentation-induced vertical gradient in particle fraction. Quantitative relation of the vertical coordinate to the clay particle fraction in these samples allows determination of a phase diagram for these Na-fluorohectorite systems, as a function of the particle fraction and salt concentration.
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Affiliation(s)
- D M Fonseca
- Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
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41
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Ghofraniha N, Conti C, Ruocco G, Zamponi F. Time-dependent nonlinear optical susceptibility of an out-of-equilibrium soft material. PHYSICAL REVIEW LETTERS 2009; 102:038303. [PMID: 19257402 DOI: 10.1103/physrevlett.102.038303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Indexed: 05/27/2023]
Abstract
We investigate the time-dependent nonlinear optical absorption of a clay dispersion (Laponite) in an organic dye (rhodamine B) water solution displaying liquid-arrested state transition. Specifically, we determine the characteristic time tauD of the nonlinear susceptibility buildup due to the Soret effect. By comparing tauD with the relaxation time provided by standard dynamic light scattering measurements we report on the decoupling of the two collective diffusion times at the two very different length scales during the aging of the out-of-equilibrium system. With this demonstration experiment we also show the potentiality of nonlinear optics measurements in the study of the late stage of arrest in soft materials.
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Affiliation(s)
- Neda Ghofraniha
- Dipartimento di Fisica, Università di Roma La Sapienza, P. A. Moro 2, 00185, Roma, Italy
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de Azevedo EN, Engelsberg M. Strongly damped dynamics of nematically ordered colloidal clay platelets in a magnetic field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:1175-1180. [PMID: 19072575 DOI: 10.1021/la803110f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The anisotropy of the diffusivity of water molecules, probed via (1)H nuclear magnetic resonance imaging techniques, is used to study the extremely slow dynamics in the nematic phase of synthetic Na-fluorhectorite platelets in aqueous suspension. The anisotropy of the diamagnetic susceptibility of the platelets Deltachi, and the torque experienced in an applied magnetic field, permit one to monitor the time evolution starting from two different initial conditions. The dynamics of the ordered platelets can be modeled by a one-dimensional Fokker-Planck equation, which permits a satisfactory description of the experimental results. From the torque-free evolution, one concludes that the process is diffusive with an extremely slow rotational diffusivity D(phi) = 9.9 x 10(- 3) rad(2)/h. The forced evolution requires a numerical solution of the full Fokker-Planck equation and yields an effective, per platelet, diamagnetic susceptibility anisotropy Deltachi = - 1.63 x 10(- 20) J/T(2).
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Affiliation(s)
- Eduardo N de Azevedo
- Programa de Pos-Graduacao em Ciencia de Materiais, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901, Recife, Pernambuco, Brazil
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Seydel T, Wiegart L, Juranyi F, Struth B, Schober H. Unaffected microscopic dynamics of macroscopically arrested water in dilute clay gels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:061403. [PMID: 19256837 DOI: 10.1103/physreve.78.061403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Indexed: 05/27/2023]
Abstract
Adequate clay minerals considerably affect the macroscopic mechanical behavior of water even at concentrations of a few percent. Thus when 2 wt. % laponite clay mineral nanoparticles are added to water, the resulting colloidal suspension after some time takes on the semisolid characteristics of a jellylike material at room temperature. Cold neutron time-of-flight spectroscopy data are in agreement with the assumption that notwithstanding this macroscopic change, the mobility of the water molecules on intermolecular and intramolecular length scales remains largely unaffected. This observation is discussed in the context of the properties and the role of water in different more or less dilute ionic environments. The result contributes to the ongoing debate of the properties and role of water in living cells.
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Affiliation(s)
- Tilo Seydel
- Institut Max von Laue-Paul Langevin, Boîte Postale 156, F-38042 Grenoble Cedex 9, France.
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Jabbari-Farouji S, Tanaka H, Wegdam GH, Bonn D. Multiple nonergodic disordered states in Laponite suspensions: a phase diagram. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:061405. [PMID: 19256839 DOI: 10.1103/physreve.78.061405] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 09/22/2008] [Indexed: 05/27/2023]
Abstract
We study the time evolution of different Laponite suspensions from a low-viscosity ergodic state to a viscoelastic nonergodic state over a wide range of volume fractions and salt contents. We find that the evolution of nonergodicity parameter (Debye-Waller factor) splits into two branches for all the samples, which correspond to two distinct dynamically arrested states. At moderately high salt concentrations, on the other hand, a third nonergodic state appears that is different from the above two nonergodic states. Measurement of the conductivity of Laponite solutions in pure water shows that the contribution of counterions in the ionic strength is considerable and their role should be taken into account in interpretations of aging dynamics and the phase diagram. Based on these data and available data in the literature, we propose a (nonequilibrium) phase diagram for Laponite suspensions.
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Affiliation(s)
- S Jabbari-Farouji
- Van der Waals-Zeeman Institute, University of Amsterdam, 1018XE Amsterdam, The Netherlands
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Oppong FK, Coussot P, de Bruyn JR. Gelation on the microscopic scale. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:021405. [PMID: 18850834 DOI: 10.1103/physreve.78.021405] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Indexed: 05/26/2023]
Abstract
Particle-tracking methods are used to study gelation in a colloidal suspension of Laponite clay particles. We track the motion of small fluorescent polystyrene spheres added to the suspension, and obtain the micron-scale viscous and elastic moduli of the material from their mean-squared displacement. The fluorescent spheres move subdiffusively due to the microstructure of the suspension, with the diffusive exponent decreasing from close to one at early times to near zero as the material gels. The particle-tracking data show that the system becomes more heterogeneous on the microscopic scale as gelation proceeds. We also determine the bulk-scale moduli using small-amplitude oscillatory shear rheometry. Both the macroscopic and microscopic moduli increase with time, and on both scales we observe a transition from a primarily viscous fluid to an elastic gel. We find that the gel point, determined as the time at which the viscous and elastic moduli are equal, is length-scale dependent--gelation occurs earlier on the bulk scale than on the microscopic scale.
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Affiliation(s)
- Felix K Oppong
- Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada N6A 3K7.
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