1
|
Brunchi CE, Morariu S. Laponite ®-From Dispersion to Gel-Structure, Properties, and Applications. Molecules 2024; 29:2823. [PMID: 38930887 PMCID: PMC11206873 DOI: 10.3390/molecules29122823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/05/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
Laponite® (LAP) is an intensively studied synthetic clay due to the versatility given by its layered structure, which makes it usable in various applications. This review describes the multifaceted properties and applications of LAP in aqueous dispersions and gel systems. The first sections of the review discuss the LAP structure and the interactions between clay discs in an aqueous medium under different conditions (such as ionic strength, pH, temperature, and the addition of polymers) in order to understand the function of clay in tailoring the properties of the designed material. Additionally, the review explores the aging phenomenon characteristic of LAP aqueous dispersions as well as the development of shake-gels by incorporating LAP. The second part shows the most recent studies on materials containing LAP with possible applicability in the drilling industry, cosmetics or care products industry, and biomedical fields. By elucidating the remarkable versatility and ease of integration of LAP into various matrices, this review underscores its significance as a key ingredient for the creation of next-generation materials with tailored functionalities.
Collapse
Affiliation(s)
| | - Simona Morariu
- “Petru Poni” Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi, Romania;
| |
Collapse
|
2
|
Mehta S, Bahadur J, Sharma SK, Sen D. Interparticle interaction-dependent jamming in colloids: insights into glass transition and morphology modulation during rapid evaporation-induced assembly. SOFT MATTER 2024; 20:375-387. [PMID: 38099855 DOI: 10.1039/d3sm01186k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Understanding the role of interparticle interactions in jamming phenomena is essential for gaining insights into the intriguing glass transition behavior observed in atomic and molecular systems. In this study, we investigate the jamming behavior of colloids with tunable interparticle interactions during evaporation-induced assembly (EIA). By manipulating the interaction among charged colloids using cationic polyethyleneimine (PEI) through electro-sorption and subsequent free polymer induced repulsion, we observe distinct jamming behavior in silica colloids during EIA, depending on the interparticle interactions. Silica colloids with strong repulsive interactions exhibit a repulsive colloidal glass state with a volume fraction of silica colloids in supraparticle ϕ ∼ 0.70. On the other hand, PEI-mediated attractive interactions among silica colloids lead to an attractive colloidal glass phase with a significantly lower ϕ ∼ 0.43. Free polymer induced repulsion of colloids at higher PEI concentration once again results in a repulsive glassy state with ϕ ∼ 0.61. Furthermore, we revealed that interparticle interactions not only influence the jamming behavior but also play a significant role in shaping the morphology of self-assembled structures during EIA, and the assembled structure undergoes a morphological reentrant transition from a doughnut-like shape to a spherical form and again back to a doughnut-like configuration. Jamming-dependent evolution of micropores and dynamics of the confined PEI have been probed using positron annihilation lifetime spectroscopy (PALS) and broadband dielectric spectroscopy (BDS). PALS reveals distinct variations in the micropores of the supraparticles with different PEI loadings, confirming the impact of jamming on the evolution of the micropores within the supraparticles. BDS measurements uncover non-monotonic dynamics of PEI molecules confined in the evolved pore network. It is revealed that the reentrant jamming behavior of colloids, modulated by PEI, holds profound significance for the long-term stability of supraparticles.
Collapse
Affiliation(s)
- Swati Mehta
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Jitendra Bahadur
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Sandeep K Sharma
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Debasis Sen
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| |
Collapse
|
3
|
Frka-Petesic B, Parton TG, Honorato-Rios C, Narkevicius A, Ballu K, Shen Q, Lu Z, Ogawa Y, Haataja JS, Droguet BE, Parker RM, Vignolini S. Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications. Chem Rev 2023; 123:12595-12756. [PMID: 38011110 PMCID: PMC10729353 DOI: 10.1021/acs.chemrev.2c00836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Indexed: 11/29/2023]
Abstract
Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.
Collapse
Affiliation(s)
- Bruno Frka-Petesic
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- International
Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Thomas G. Parton
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Camila Honorato-Rios
- Department
of Sustainable and Bio-inspired Materials, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Aurimas Narkevicius
- B
CUBE − Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
| | - Kevin Ballu
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Qingchen Shen
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Zihao Lu
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Yu Ogawa
- CERMAV-CNRS,
CS40700, 38041 Grenoble cedex 9, France
| | - Johannes S. Haataja
- Department
of Applied Physics, Aalto University School
of Science, P.O. Box
15100, Aalto, Espoo FI-00076, Finland
| | - Benjamin E. Droguet
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Richard M. Parker
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Silvia Vignolini
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| |
Collapse
|
4
|
Lapasin R, Grassi M, Abrami M, Šebenik U. Structural evolution of salt-free aqueous Laponite dispersions: A study based on low-field NMR relaxometry and rheological investigations. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
5
|
Chen Y, Rogers SA, Narayanan S, Harden JL, Leheny RL. Microscopic ergodicity breaking governs the emergence and evolution of elasticity in glass-forming nanoclay suspensions. Phys Rev E 2020; 102:042619. [PMID: 33212706 DOI: 10.1103/physreve.102.042619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/10/2020] [Indexed: 11/07/2022]
Abstract
We report a study combining x-ray photon correlation spectroscopy (XPCS) with in situ rheology to investigate the microscopic dynamics and mechanical properties of aqueous suspensions of the synthetic hectorite clay Laponite, which is composed of charged, nanometer-scale, disk-shaped particles. The suspensions, with particle concentrations ranging from 3.25 to 3.75 wt %, evolve over time from a fluid to a soft glass that displays aging behavior. The XPCS measurements characterize the localization of the particles during the formation and aging of the soft-glass state. The fraction of localized particles, f_{0}, increases rapidly during the early formation stage and grows more slowly during subsequent aging, while the characteristic localization length r_{loc} steadily decreases. Despite the strongly varying rates of aging at different concentrations, both f_{0} and r_{loc} scale with the elastic shear modulus G^{'} in a manner independent of concentration. During the later aging stage, the scaling between r_{loc} and G^{'} agrees quantitatively with a prediction of naive mode coupling theory. Breakdown of agreement with the theory during the early formation stage indicates the prevalence of dynamic heterogeneity, suggesting the soft solid forms through precursors of dynamically localized clusters.
Collapse
Affiliation(s)
- Yihao Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Simon A Rogers
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Champaign, Illinois 61801, USA
| | - Suresh Narayanan
- X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - James L Harden
- Department of Physics & CAMaR, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Robert L Leheny
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| |
Collapse
|
6
|
Rheology of aqueous dispersions of Laponite and TEMPO-oxidized nanofibrillated cellulose. Carbohydr Polym 2020; 240:116330. [DOI: 10.1016/j.carbpol.2020.116330] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 12/31/2022]
|
7
|
Frka-Petesic B, Kelly JA. Retrieving the Coassembly Pathway of Composite Cellulose Nanocrystal Photonic Films from their Angular Optical Response. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906889. [PMID: 32249481 PMCID: PMC7116217 DOI: 10.1002/adma.201906889] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 01/15/2020] [Indexed: 05/15/2023]
Abstract
Aqueous suspensions of cellulose nanocrystals (CNCs) are known to self-assemble into a chiral nematic liquid crystalline phase, leading to solid-state nanostructured colored films upon solvent evaporation, even in the presence of templating agents. The angular optical response of these structures, and therefore their visual appearance, are completely determined by the spatial arrangement of the CNCs when the drying suspension undergoes a transition from a flowing and liquid crystalline state to a kinetically arrested state. Here, it is demonstrated how the angular response of the final film allows for retrieval of key physical properties and the chemical composition of the suspension at the onset of the kinetic arrest, thus capturing a snapshot of the past. To illustrate this methodology, a dynamically evolving sol-gel coassembly process is investigated by adding various amounts of organosilica precursor, namely, 1,2-bis(trimethoxysilyl)ethane. The influence of organosilica condensation on the kinetic arrest can be tracked and thus explains the angular response of the resulting films. The a posteriori and in situ approach is general; it can be applied to a variety of additives in CNC-based films and it allows access to key rheological information of the suspension without using any dedicated rheological technique.
Collapse
Affiliation(s)
- Bruno Frka-Petesic
- Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Joel A. Kelly
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada, V6T 1Z1
| |
Collapse
|
8
|
Nigro V, Ruzicka B, Ruta B, Zontone F, Bertoldo M, Buratti E, Angelini R. Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b01560] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Valentina Nigro
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
| | - Barbara Ruzicka
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
| | - Beatrice Ruta
- France Univ Lyon, Universitè Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69100 Villeurbanne, France
- ESRF The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Federico Zontone
- ESRF The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Monica Bertoldo
- Istituto per la Sintesi Organica e la Fotoreattività del Consiglio Nazionale delle Ricerche (ISOF-CNR), via P. Gobetti
101, 40129 Bologna, Italy
| | - Elena Buratti
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
| | - Roberta Angelini
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
| |
Collapse
|
9
|
Lebovka NI, Vygornitskii NV, Tarasevich YY. Relaxation in two-dimensional suspensions of rods as driven by Brownian diffusion. Phys Rev E 2019; 100:042139. [PMID: 31770898 DOI: 10.1103/physreve.100.042139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Indexed: 06/10/2023]
Abstract
Relaxation in a two-dimensional suspensions containing rods was studied by using dynamic Monte Carlo simulations. An off-lattice model with continuous positional and orientational degrees of freedom was considered. The initial state was produced by using a random sequential adsorption model. During the relaxation, the rods underwent translational and rotational Brownian motions. The simulations were run at different values of number density ρ (the number of rods per unit area) and of the initial orientation order parameter S_{i}. The rods were assumed to have core-shell structures. The evolutions of both the connectivity and the order parameter have revealed different relaxation behavior.
Collapse
Affiliation(s)
- Nikolai I Lebovka
- Department of Physical Chemistry of Disperse Minerals, F. D. Ovcharenko Institute of Biocolloidal Chemistry, NAS of Ukraine, Kyiv, 03142, Ukraine
- Department of Physics, Taras Shevchenko Kyiv National University, Kyiv, 01033, Ukraine
| | - Nikolai V Vygornitskii
- Department of Physical Chemistry of Disperse Minerals, F. D. Ovcharenko Institute of Biocolloidal Chemistry, NAS of Ukraine, Kyiv, 03142, Ukraine
| | - Yuri Yu Tarasevich
- Laboratory of Mathematical Modeling, Astrakhan State University, Astrakhan, 414056, Russia
| |
Collapse
|
10
|
Rao A, Divoux T, McKinley GH, Hart AJ. Shear melting and recovery of crosslinkable cellulose nanocrystal-polymer gels. SOFT MATTER 2019; 15:4401-4412. [PMID: 31095139 DOI: 10.1039/c8sm02647e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cellulose nanocrystals (CNC) are naturally-derived nanostructures of growing importance for the production of composites having attractive mechanical properties, and offer improved sustainability over purely petroleum-based alternatives. Fabrication of CNC composites typically involves extrusion of CNC suspensions and gels in a variety of solvents, in the presence of additives such as polymers and curing agents. Most studies so far have focused on aqueous CNC gels, yet the behavior of CNC-polymer gels in organic solvents is important to their wider processability. Here, we study the rheological behavior of composite polymer-CNC gels in dimethylformamide, which include additives for both UV and thermal crosslinking. Using rheometry coupled with in situ infrared spectroscopy, we show that under external shear, CNC-polymer gels display progressive and irreversible failure of the hydrogen bond network that is responsible for their pronounced elastic properties. In the absence of cross-linking additives, the polymer-CNC gels show an instantaneous but partial recovery of their viscoelasticity upon cessation of flow, whereas, the presence of additives allows the gels to recover over much longer timescale via van der Waals interactions. By exploring a broad range of shear history and CNC concentrations, we construct master curves for the temporal evolution of the viscoelastic properties of the polymer-CNC gels, illustrating universality of the observed dynamics with respect to gel composition and flow conditions. We find that polymer-CNC composite gels display a number of the distinctive features of colloidal glasses and, strikingly, that their response to the flow conditions encountered during processing can be tuned by chemical additives. These findings have implications for processing of dense CNC-polymer composites in solvent casting, 3D printing, and other manufacturing techniques.
Collapse
Affiliation(s)
- Abhinav Rao
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | | | | | | |
Collapse
|
11
|
Poling-Skutvik R, Roberts RC, Slim AH, Narayanan S, Krishnamoorti R, Palmer JC, Conrad JC. Structure Dominates Localization of Tracers within Aging Nanoparticle Glasses. J Phys Chem Lett 2019; 10:1784-1789. [PMID: 30916569 DOI: 10.1021/acs.jpclett.9b00309] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigate the transport and localization of tracer probes in a glassy matrix as a function of relative size using dynamic X-ray scattering experiments and molecular dynamics simulations. The quiescent relaxations of tracer particles evolve with increasing waiting time, tw. The corresponding relaxation times increase exponentially at small tw and then transition to a power-law behavior at longer tw. As tracer size decreases, the aging behavior weakens and the particles become less localized within the matrix until they delocalize at a critical size ratio δ0 ≈ 0.38. Localization does not vary with sample age even as the relaxations slow by approximately an order of magnitude, suggesting that matrix structure controls tracer localization.
Collapse
Affiliation(s)
- Ryan Poling-Skutvik
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| | - Ryan C Roberts
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| | - Ali H Slim
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| | - Suresh Narayanan
- Advanced Photon Source , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Ramanan Krishnamoorti
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| | - Jeremy C Palmer
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| | - Jacinta C Conrad
- Department of Chemical and Biomolecular Engineering , University of Houston , Houston , Texas 77204-4004 , United States
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Niu R, Heidt S, Sreij R, Dekker RI, Hofmann M, Palberg T. Formation of a transient amorphous solid in low density aqueous charged sphere suspensions. Sci Rep 2017; 7:17044. [PMID: 29213089 PMCID: PMC5719089 DOI: 10.1038/s41598-017-17106-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/22/2017] [Indexed: 11/09/2022] Open
Abstract
Colloidal glasses formed from hard spheres, nearly hard spheres, ellipsoids and platelets or their attractive variants, have been studied in great detail. Complementing and constraining theoretical approaches and simulations, the many different types of model systems have significantly advanced our understanding of the glass transition in general. Despite their early prediction, however, no experimental charged sphere glasses have been found at low density, where the competing process of crystallization prevails. We here report the formation of a transient amorphous solid formed from charged polymer spheres suspended in thoroughly deionized water at volume fractions of 0.0002-0.01. From optical experiments, we observe the presence of short-range order and an enhanced shear rigidity as compared to the stable polycrystalline solid of body centred cubic structure. On a density dependent time scale of hours to days, the amorphous solid transforms into this stable structure. We further present preliminary dynamic light scattering data showing the evolution of a second slow relaxation process possibly pointing to a dynamic heterogeneity known from other colloidal glasses and gels. We compare our findings to the predicted phase behaviour of charged sphere suspensions and discuss possible mechanisms for the formation of this peculiar type of colloidal glass.
Collapse
Affiliation(s)
- Ran Niu
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany.
| | - Sabrina Heidt
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
- Graduate School Materials Science in Mainz, Staudinger Weg 9, D-55128, Mainz, Germany
| | - Ramsia Sreij
- Department of Chemistry Physical and Biophysical Chemistry (PC III), Bielefeld University, D-33615, Bielefeld, Germany
| | - Riande I Dekker
- Debye Institute for Nanomaterials Science, Utrecht University, NL-3584 CC, Utrecht, The Netherlands
| | - Maximilian Hofmann
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
| |
Collapse
|
14
|
Rheology of Laponite-scleroglucan hydrogels. Carbohydr Polym 2017; 168:290-300. [DOI: 10.1016/j.carbpol.2017.03.068] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/15/2017] [Accepted: 03/21/2017] [Indexed: 11/24/2022]
|
15
|
Safdari H, Cherstvy AG, Chechkin AV, Bodrova A, Metzler R. Aging underdamped scaled Brownian motion: Ensemble- and time-averaged particle displacements, nonergodicity, and the failure of the overdamping approximation. Phys Rev E 2017; 95:012120. [PMID: 28208482 DOI: 10.1103/physreve.95.012120] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Indexed: 06/06/2023]
Abstract
We investigate both analytically and by computer simulations the ensemble- and time-averaged, nonergodic, and aging properties of massive particles diffusing in a medium with a time dependent diffusivity. We call this stochastic diffusion process the (aging) underdamped scaled Brownian motion (UDSBM). We demonstrate how the mean squared displacement (MSD) and the time-averaged MSD of UDSBM are affected by the inertial term in the Langevin equation, both at short, intermediate, and even long diffusion times. In particular, we quantify the ballistic regime for the MSD and the time-averaged MSD as well as the spread of individual time-averaged MSD trajectories. One of the main effects we observe is that, both for the MSD and the time-averaged MSD, for superdiffusive UDSBM the ballistic regime is much shorter than for ordinary Brownian motion. In contrast, for subdiffusive UDSBM, the ballistic region extends to much longer diffusion times. Therefore, particular care needs to be taken under what conditions the overdamped limit indeed provides a correct description, even in the long time limit. We also analyze to what extent ergodicity in the Boltzmann-Khinchin sense in this nonstationary system is broken, both for subdiffusive and superdiffusive UDSBM. Finally, the limiting case of ultraslow UDSBM is considered, with a mixed logarithmic and power-law dependence of the ensemble- and time-averaged MSDs of the particles. In the limit of strong aging, remarkably, the ordinary UDSBM and the ultraslow UDSBM behave similarly in the short time ballistic limit. The approaches developed here open ways for considering other stochastic processes under physically important conditions when a finite particle mass and aging in the system cannot be neglected.
Collapse
Affiliation(s)
- Hadiseh Safdari
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
- Department of Physics, Shahid Beheshti University, 19839 Tehran, Iran
| | - Andrey G Cherstvy
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Aleksei V Chechkin
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
- Institute for Theoretical Physics, Kharkov Institute of Physics and Technology, 61108 Kharkov, Ukraine
- Department of Physics & Astronomy, University of Padova, "Galileo Galilei" - DFA, 35131 Padova, Italy
| | - Anna Bodrova
- Institute of Physics, Humboldt University Berlin, 12489 Berlin, Germany
- Faculty of Physics, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Ralf Metzler
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
| |
Collapse
|
16
|
Ali S, Bandyopadhyay R. Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay. SOFT MATTER 2016; 12:414-421. [PMID: 26477340 DOI: 10.1039/c5sm01700a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Na-montmorillonite is a natural clay mineral and is available in abundance in nature. The aqueous dispersions of charged and anisotropic platelets of this mineral exhibit non-ergodic kinetically arrested states ranging from soft glassy phases dominated by interparticle repulsions to colloidal gels stabilized by salt induced attractive interactions. When the salt concentration in the dispersing medium is varied systematically, viscoelasticity and yield stress of the dispersion show non-monotonic behavior at a critical salt concentration, thus signifying a morphological change in the dispersion microstructures. We directly visualize the microscopic structures of these kinetically arrested phases using cryogenic scanning electron microscopy. We observe the existence of honeycomb-like network morphologies for a wide range of salt concentrations. The transition of the gel morphology, dominated by overlapping coin (OC) and house of cards (HoC) associations of clay particles at low salt concentrations to a new network structure dominated by face-face coagulation of platelets, is observed across the critical salt concentration. We further assess the stability of these gels under gravity using electroacoustics. This study, performed for concentrated clay dispersions for a wide concentration range of externally added salt, is useful in our understanding of many geophysical phenomena that involve the salt induced aggregation of natural clay minerals.
Collapse
Affiliation(s)
- Samim Ali
- Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560080, India.
| | | |
Collapse
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Strachota B, Matějka L, Zhigunov A, Konefał R, Spěváček J, Dybal J, Puffr R. Poly(N-isopropylacrylamide)-clay based hydrogels controlled by the initiating conditions: evolution of structure and gel formation. SOFT MATTER 2015; 11:9291-9306. [PMID: 26428943 DOI: 10.1039/c5sm01996f] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The formation of the hydrogel poly(N-isopropylacrylamide)-clay (LAPONITE®) by redox polymerization was investigated, and the main factors governing the gel build-up were determined. The significant effect of the redox initiating system ammonium peroxodisulfate (APS) and tetramethylethylenediamine (TEMED) on gel formation and structure was established, making it possible to control the structure of the gel. Moreover, the pre-reaction stage involving the quality of the clay exfoliation in an aqueous suspension and the interaction of reaction components with the clay play a role in controlling the polymerization and gel structure. The molecular and phase structure evolution during polymerization was followed in situ by the following independent techniques: Fourier transform infrared spectroscopy (FTIR), chemorheology, small-angle X-ray scattering (SAXS) and ultraviolet-visible spectroscopy (UV/Vis). The combination of these methods enabled us to describe in detail particular progress stages during the gel formation and determine the correlation of the corresponding processes on a time and conversion scale. The mechanism of gel formation was refined based on these experimental results.
Collapse
Affiliation(s)
- Beata Strachota
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Libor Matějka
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Alexander Zhigunov
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Rafał Konefał
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Jiří Spěváček
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Jiří Dybal
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| | - Rudolf Puffr
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
| |
Collapse
|
19
|
|
20
|
Fabrication of gelatin–laponite composite films: Effect of the concentration of laponite on physical properties and the freshness of meat during storage. Food Hydrocoll 2015. [DOI: 10.1016/j.foodhyd.2014.10.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
21
|
de Melo Marques FA, Angelini R, Zaccarelli E, Farago B, Ruta B, Ruocco G, Ruzicka B. Structural and microscopic relaxations in a colloidal glass. SOFT MATTER 2015; 11:466-471. [PMID: 25406421 DOI: 10.1039/c4sm02010c] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The aging dynamics of a colloidal glass has been studied by multiangle dynamic light scattering, neutron spin echo, X-ray photon correlation spectroscopy and molecular dynamics simulations. The two relaxation processes, microscopic (fast) and structural (slow), have been investigated in an unprecedentedly wide range of time and length scales covering both ergodic and nonergodic regimes. The microscopic relaxation time remains diffusive at all length scales across the glass transition scaling with wavevector Q as Q(-2). The length-scale dependence of structural relaxation time changes from diffusive, characterized by a Q(-2)-dependence in the early stages of aging, to a Q(-1)-dependence in the full aging regime which marks a discontinuous hopping dynamics. Both regimes are associated with a stretched behaviour of the correlation functions. We expect these findings to provide a general description of both relaxations across the glass transition.
Collapse
Affiliation(s)
- Flavio Augusto de Melo Marques
- Center for Life Nano Science, IIT@Sapienza, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy.
| | | | | | | | | | | | | |
Collapse
|
22
|
Zulian L, Augusto de Melo Marques F, Emilitri E, Ruocco G, Ruzicka B. Dual aging behaviour in a clay-polymer dispersion. SOFT MATTER 2014; 10:4513-4521. [PMID: 24817524 DOI: 10.1039/c4sm00172a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Clay-polymer compounds have recently attracted increasing attention due to their intriguing physical properties in colloidal science and their rheological non-trivial behaviour in technological applications. Aqueous solutions of Laponite clay spontaneously age from a liquid up to an arrested state of different nature (gel or glass) depending on the colloidal volume fraction and ionic strength. We have investigated, through dynamic light scattering, how the aging dynamics of Laponite dispersions at fixed clay concentration (Cw = 2.0%) is modified by the addition of various amounts of poly(ethylene oxide) (PEO) (CPEO = (0.05 ÷ 0.50) %) at two different molecular weights (Mw = 100 kg mol(-1) and Mw = 200 kg mol(-1)). A surprising and intriguing phenomenon has been observed: the existence of a critical polymer concentration C that discriminates between two different aging dynamics. With respect to pure Laponite systems the aging will be assisted (faster) or hindered (slower) for PEO concentrations respectively lower (CPEO < C) or higher (CPEO > C) than the critical concentration. In this way a control on the aging dynamics of PEO-Laponite systems is obtained. A possible explanation based on the balance of competitive mechanisms related to the progressive saturation of the clay surface by polymers is proposed. This study shows how a real control on the aging speed of the PEO-Laponite system is at hand and renders possible a real control of the complex interparticle interaction potential.
Collapse
Affiliation(s)
- Laura Zulian
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano Bicocca, Via Roberto Cozzi, 53 20125 Milano, Italy.
| | | | | | | | | |
Collapse
|
23
|
Saha D, Joshi YM, Bandyopadhyay R. Investigation of the dynamical slowing down process in soft glassy colloidal suspensions: comparisons with supercooled liquids. SOFT MATTER 2014; 10:3292-3300. [PMID: 24637644 DOI: 10.1039/c4sm00187g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The primary and secondary relaxation timescales of aging colloidal suspensions of Laponite are estimated from intensity autocorrelation functions obtained in dynamic light scattering (DLS) experiments. The dynamical slowing down of these relaxation processes are compared with observations in fragile supercooled liquids by establishing a one-to-one mapping between the waiting time since filtration of a Laponite suspension and the inverse of the temperature of a supercooled liquid that is rapidly quenched towards its glass transition temperature. New timescales associated with primary and secondary relaxation processes, such as the characteristic timescale associated with the slowdown of the secondary relaxation process and the glass transition time, are extracted to describe the phenomenon of dynamical arrest in Laponite suspensions. In results that are strongly reminiscent of those extracted from supercooled liquids approaching their glass transitions, it is demonstrated that a strong coupling exists between the primary and secondary relaxation processes of aging Laponite suspensions in the cage-forming regime. Furthermore, the experimental data presented here clearly demonstrate the self-similar nature of the aging dynamics of Laponite suspensions within a range of sample concentrations.
Collapse
Affiliation(s)
- Debasish Saha
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India.
| | | | | |
Collapse
|
24
|
Abstract
It has recently been shown that suspensions of long and thin charged fibrous viruses (fd) form a glass at low ionic strengths. The corresponding thick electric double layers give rise to long-ranged repulsive electrostatic interactions, which lead to caging and structural arrest at concentrations far above the isotropic-nematic coexistence region. Structural arrest and freezing of the orientational texture are found to occur at the same concentration. In addition, various types of orientational textures are equilibrated below the glass transition concentration, ranging from a chiral-nematic texture with a large pitch (of about 100 μm), an X-pattern, and a tightly packed domain texture, consisting of helical domains with a relatively small pitch (of about 10 μm) and twisted boundaries. The dynamics of both particles as well as the texture are discussed, below and above the glass transition. Dynamic light scattering correlation functions exhibit two dynamical modes, where the slow mode is attributed to the elasticity of helical domains. On approach of the glass-transition concentration, the slow mode increases in amplitude, while as the amplitudes of the fast and slow mode become equal at the glass transition. Finally, interesting features of the "transient" behaviors of charged fd-rod glass are shown as the initial caging due to structural arrest, the propagation of flow originating from stress release, and the transition to the final metastable glass state. In addition to the intensity correlation function, power spectra are presented as a function of the waiting time, at the zero-frequency limit that may access to the thermal anomalities in a charged system.
Collapse
Affiliation(s)
- Kyongok Kang
- Forschungszentrum Jülich, Institute of Complex Systems (ICS-3), D-52425 Jülich, Germany.
| |
Collapse
|
25
|
Wang M, Winter HH, Auernhammer GK. Time and frequency dependent rheology of reactive silica gels. J Colloid Interface Sci 2014; 413:159-66. [DOI: 10.1016/j.jcis.2013.09.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 10/26/2022]
|
26
|
Zaccone A, Crassous JJ, Ballauff M. Colloidal gelation with variable attraction energy. J Chem Phys 2013; 138:104908. [PMID: 23514520 DOI: 10.1063/1.4794695] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present an approximation scheme to the master kinetic equations for aggregation and gelation with thermal breakup in colloidal systems with variable attraction energy. With the cluster fractal dimension df as the only phenomenological parameter, rich physical behavior is predicted. The viscosity, the gelation time, and the cluster size are predicted in closed form analytically as a function of time, initial volume fraction, and attraction energy by combining the reversible clustering kinetics with an approximate hydrodynamic model. The fractal dimension df modulates the time evolution of cluster size, lag time and gelation time, and of the viscosity. The gelation transition is strongly nonequilibrium and time-dependent in the unstable region of the state diagram of colloids where the association rate is larger than the dissociation rate. Only upon approaching conditions where the initial association and the dissociation rates are comparable for all species (which is a condition for the detailed balance to be satisfied) aggregation can occur with df = 3. In this limit, homogeneous nucleation followed by Lifshitz-Slyozov coarsening is recovered. In this limited region of the state diagram the macroscopic gelation process is likely to be driven by large spontaneous fluctuations associated with spinodal decomposition.
Collapse
Affiliation(s)
- Alessio Zaccone
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
| | | | | |
Collapse
|
27
|
|
28
|
Atmuri AK, Bhatia SR. Polymer-mediated clustering of charged anisotropic colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:3179-3187. [PMID: 23419051 DOI: 10.1021/la304062r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Formation of stable, dense nanoparticle clusters is interesting due to both the underlying physics and use of nanoclusters in applications such as digital printing, imaging and biosensing, and energy storage. Here, we explore formation of nanoparticle clusters in dispersions of the model disk-shaped colloid Laponite. Under basic conditions, the model disk-shaped colloid Laponite forms a repulsive glass in water due to strong electrostatic interactions. Addition of a nonadsorbing polymer, the sodium salt of poly(acrylic acid) (PAA), induces a depletion attraction between particles. Through dynamic light scattering (DLS) and rheology, we see that the polymer initially causes a transition from the glassy phase to an ergodic fluid. Samples at higher particle concentration age to a weak nonergodic state, while samples at lower Laponite remain as fluids. As the strength of attraction between particles is increased, we find an increase in the fast relaxation time measured via dynamic light scattering (e.g., slowing of the short-time diffusion of a single particle). While this may in part be attributed to an increase in the ionic strength, the aging behavior and glass-fluid transition we observe appear to be unique to the presence of polymer, suggesting that depletion plays an important role. DLS data on the fluid samples were consistent with two widely spaced diffusive relaxation modes, corresponding to motion of single particles and motion of large clusters, although other slow dynamic processes may be present. On the basis of the estimated volume fraction and depletion attraction, we believe the Laponite-PAA suspensions to be either fluids of stable clusters or glasses of clusters, although it is possible that the nonergodic state we observe is instead a gel of clusters. Additionally, the cluster size was found to be stable for at least 120 days and was directly related to the polymer concentration. This may serve as an important means of tuning cluster size in products and processes based on dense nanoparticle assemblies.
Collapse
Affiliation(s)
- Anand K Atmuri
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | | |
Collapse
|
29
|
Fuliński A. Communication: How to generate and measure anomalous diffusion in simple systems. J Chem Phys 2013; 138:021101. [DOI: 10.1063/1.4775737] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
30
|
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.
Collapse
Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, India
| | | |
Collapse
|
31
|
Morariu S, Bercea M. Effect of Temperature and Aging Time on the Rheological Behavior of Aqueous Poly(ethylene glycol)/Laponite RD Dispersions. J Phys Chem B 2011; 116:48-54. [DOI: 10.1021/jp208136g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simona Morariu
- Petru Poni Institute of Macromolecular Chemistry, 41-A Grigore Ghica Vodǎ Alley, 700487 Iasi, Romania
| | - Maria Bercea
- Petru Poni Institute of Macromolecular Chemistry, 41-A Grigore Ghica Vodǎ Alley, 700487 Iasi, Romania
| |
Collapse
|
32
|
Santinath Singh S, Aswal VK, Bohidar HB. Internal structures of agar-gelatin co-hydrogels by light scattering, small-angle neutron scattering and rheology. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:62. [PMID: 21706280 DOI: 10.1140/epje/i2011-11062-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/16/2011] [Accepted: 05/30/2011] [Indexed: 05/31/2023]
Abstract
Internal structures of agar-gelatin co-hydrogels were investigated as a function of their volumetric mixing ratio, [Formula: see text] , 1.0 and 2.0 using dynamic light scattering (DLS), small-angle neutron scattering (SANS) and rheology. The degree of non-ergodicity ( X = 0.2 ± 0.02) , which was extracted as a heterodyne contribution from the measured dynamic structure factor data remained less than that of homogeneous solutions where ergodicity is expected (X = 10. The static structure factor, I(q) , results obtained from SANS were interpreted in the Guinier regime (low-q , which implied the existence of ≈ 250 nm long rod-like structures (double-helix bundles), and the power law (intermediate-q regions) yielded I (q) ~ q(−α) with α = 2.3 , 1.8 and 1.6 for r = 0.5 , 1.0 and 2.0. This is indicative of the presence of Gaussian chains at low r , while at r = 2 there was a propensity of rod-shaped structures. The gel strength and transition temperatures measured from frequency sweep and temperature ramp studies were suggestive of the presence of a stronger association between the two biopolymer networks at higher r . The results indicate that the internal structures of agar-gelatin co-hydrogels were highly dependent on the volumetric mixing ratio.
Collapse
Affiliation(s)
- S Santinath Singh
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India.
| | | | | |
Collapse
|
33
|
Fuliński A. Anomalous diffusion and weak nonergodicity. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:061140. [PMID: 21797335 DOI: 10.1103/physreve.83.061140] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Indexed: 05/31/2023]
Abstract
Ergodic behavior of the class of G processes G(t)=∫(t(m))(t)du K(t,u)ξ(u)-∫(t(m))(0)du K(0,u)ξ(u), (ξ(t))=0, (ξ(t)ξ(s))=ϕ(|t-s|) is examined. Ergodicproperties are only G extensions of normal diffusion (K=1) and of Mandelbrot-Van Ness fractional diffusion [K(t,u)=K(t-u), t(m)→-∞]. Any deviation from these two types results in weak ergodicity breaking which thus is neither exceptional nor limited to some specific events but is typical for much wider class of processes. G processes driven by ξ(t) with nonvanishing correlations are important for describing transport in strongly nonequilibrium systems and may be responsible for peculiarities of diffusion found in biological, glassy, and nanoscale systems.
Collapse
Affiliation(s)
- A Fuliński
- M. Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
| |
Collapse
|
34
|
Paineau E, Bihannic I, Baravian C, Philippe AM, Davidson P, Levitz P, Funari SS, Rochas C, Michot LJ. Aqueous suspensions of natural swelling clay minerals. 1. Structure and electrostatic interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5562-5573. [PMID: 21476528 DOI: 10.1021/la2001255] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this article, we present a general overview of the organization of colloidal charged clay particles in aqueous suspension by studying different natural samples with different structural charges and charge locations. Small-angle X-ray scattering experiments (SAXS) are first used to derive swelling laws that demonstrate the almost perfect exfoliation of clay sheets in suspension. Using a simple approach based on geometrical constraints, we show that these swelling laws can be fully modeled on the basis of morphological parameters only. The validity of this approach was further extended to other clay data from the literature, in particular, synthetic Laponite. For all of the investigated samples, experimental osmotic pressures can be properly described by a Poisson-Boltzmann approach for ionic strength up to 10(-3) M, which reveals that these systems are dominated by repulsive electrostatic interactions. However, a detailed analysis of the Poisson-Boltzmann treatment shows differences in the repulsive potential strength that are not directly linked to the structural charge of the minerals but rather to the charge location in the structure for tetrahedrally charged clays (beidellite and nontronites) undergoing stronger electrostatic repulsions than octahedrally charged samples (montmorillonites, laponite). Only minerals subjected to the strongest electrostatic repulsions present a true isotropic to nematic phase transition in their phase diagrams. The influence of ionic repulsions on the local order of clay platelets was then analyzed through a detailed investigation of the structure factors of the various clay samples. It appears that stronger electrostatic repulsions improve the liquidlike positional local order.
Collapse
Affiliation(s)
- Erwan Paineau
- Laboratoire Environnement et Minéralurgie, Nancy Université-CNRS, UMR 7569, BP40 54501 Vandœuvre Cedex, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Sun W, Yang Y, Wang T, Liu X, Wang C, Tong Z. Large amplitude oscillatory shear rheology for nonlinear viscoelasticity in hectorite suspensions containing poly(ethylene glycol). POLYMER 2011. [DOI: 10.1016/j.polymer.2011.01.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
36
|
Morikubo S, Sekine Y, Ikeda-Fukazawa T. Structure and dynamics of water in mixed solutions including laponite and PEO. J Chem Phys 2011; 134:044905. [DOI: 10.1063/1.3533233] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
37
|
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.
Collapse
Affiliation(s)
- F Shayeganfar
- Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran, Iran
| | | | | | | | | |
Collapse
|
38
|
Ringdal NI, Fonseca DM, Hansen EL, Hemmen H, Fossum JO. Nematic textures in colloidal dispersions of Na-fluorohectorite synthetic clay. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:041702. [PMID: 20481735 DOI: 10.1103/physreve.81.041702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Indexed: 05/22/2023]
Abstract
We have studied stable strata of gravity-induced phase separation in suspensions of synthetic Na-fluorohectorite clay in saline solutions. We have observed how the strata depend on clay concentration as well as on salt content. The mass distribution and density variation at the isotropic-nematic interface indicate that existing models and assumptions in existing simulations are able to relatively well account for the observed behavior. We suggest that discrepancies could be due to the high polydispersity and the irregular shape of our Na-fluorohectorite particles, as well as diffusive double-layer effects, which could result in a competition between nematic ordering and gelation. The dependence on ionic strength displays three main regimes irrespective of clay concentration. At low ionic strength (approximately 0.1-5 mM NaCl), the Debye screening length is longer than the van der Waals force range. In this regime, the particles repel each other electrostatically and entropy-driven Onsager-type nematic ordering may occur, although gelation effects could also play a role. For ionic strengths above about 5 mM, we believe that the van der Waals force comes into play and that particles attract each other locally according to the classical Derjaguin, Landau, Verwey, and Overbeek (DLVO) model of colloid interactions, resulting in a small-domain regime of attractive nematiclike ordering. In the third regime, for ionic strengths above approximately 10 mM, the clay particles aggregate into larger assemblies, due to the dominant van der Waals force, and the observed birefringency is reduced. We have studied the nematic phase in detail between crossed polarizers and have found textures showing nematic Schlieren patterns. By rotating the polarizers as well as the samples, we have observed examples of disclinations of strengths -1, -1/2, and +1.
Collapse
Affiliation(s)
- N I Ringdal
- Department of Physics, Norwegian University of Science and Technology, Hoegskoleringen 5, N-7491 Trondheim, Norway
| | | | | | | | | |
Collapse
|
39
|
Monoglyceride-based cubosomes stabilized by Laponite: Separating the effects of stabilizer, pH and temperature. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.01.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
40
|
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.
Collapse
Affiliation(s)
- A Shahin
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | | |
Collapse
|
41
|
Wu H, Tsoutsoura A, Lattuada M, Zaccone A, Morbidelli M. Effect of temperature on high shear-induced gelation of charge-stabilized colloids without adding electrolytes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:2761-2768. [PMID: 19845347 DOI: 10.1021/la902800x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrated previously (Wu, H.; Zaccone, A.; Tsoutsoura, A.; Lattuada, M.; Morbidelli, M. Langmuir 2009, 25, 4715) that, for a colloid stabilized by charges from both polymer chain-end groups and adsorbed sulfonate surfactants, when the surfactant surface density reaches a certain critical value, the shear-induced gelation becomes unachievable at room temperature, even at an extremely large Peclet number, Pe = 4.6 x 10(4). This is due to the presence of the short-range, repulsive hydration force generated by the adsorbed surfactant. In this work, we investigate how such hydration force affects the shear-induced gelation at higher temperatures, in the range between 303 and 338 K. It is found that a colloidal system, which does not gel at room temperature in a microchannel at a fixed Pe = 3.7 x 10(4), does gel when temperature increases to a certain value. The critical initial particle volume fraction for the gelation to occur decreases as temperature increases. These results indicate that the effect of the hydration force on the gelation decreases as temperature increases. Moreover, we have observed that at the criticality only part of the primary particles is converted to the gel network and the effective particle volume fraction forming the gel network does not change significantly with temperature. The effective particle volume fraction is also independent of the surfactant surface coverage. Since the effective particle volume fraction corresponds to space filling requirement of a standing gel network, which is mainly related to the clusters structure, this result indicates that at a given shear rate the cluster structure does not change significantly with the surfactant surface coverage. On the other hand, since the cluster morphology is a strong function of the shear rate, we have observed that when the Peclet number is lowered from Pe = 3.7 x 10(4) to 1.7 x 10(4), the effective particle volume fraction reduces from 0.19 to 0.12 at 313 K.
Collapse
Affiliation(s)
- Hua Wu
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | | | | | | | | |
Collapse
|
42
|
Zaccone A, Del Gado E. On mean coordination and structural heterogeneity in model amorphous solids. J Chem Phys 2010; 132:024906. [DOI: 10.1063/1.3284786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
43
|
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]
|
44
|
|
45
|
Shaukat A, Joshi YM, Sharma A. Tensile Deformation and Failure of Thin Films of Aging Laponite Suspension. Ind Eng Chem Res 2009. [DOI: 10.1021/ie9006326] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Asima Shaukat
- 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
| | - Ashutosh Sharma
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 India
| |
Collapse
|
46
|
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
| |
Collapse
|
47
|
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.
Collapse
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
| | | |
Collapse
|
48
|
Nakato T, Yamada Y, Miyamoto N. Photoinduced Charge Separation in a Colloidal System of Exfoliated Layered Semiconductor Controlled by Coexisting Aluminosilicate Clay. J Phys Chem B 2009; 113:1323-31. [DOI: 10.1021/jp807214w] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Teruyuki Nakato
- Division of Bio-Applications and Systems Engineering (BASE), Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588, Japan, and Department of Life, Environment, and Materials Science, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka-shi, Fukuoka 811-0295, Japan
| | - Yoshimi Yamada
- Division of Bio-Applications and Systems Engineering (BASE), Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588, Japan, and Department of Life, Environment, and Materials Science, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka-shi, Fukuoka 811-0295, Japan
| | - Nobuyoshi Miyamoto
- Division of Bio-Applications and Systems Engineering (BASE), Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588, Japan, and Department of Life, Environment, and Materials Science, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka-shi, Fukuoka 811-0295, Japan
| |
Collapse
|
49
|
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.
Collapse
Affiliation(s)
- S Jabbari-Farouji
- Van der Waals-Zeeman Institute, University of Amsterdam, 1018XE Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
50
|
Cousin F, Cabuil V, Grillo I, Levitz P. Competition between entropy and electrostatic interactions in a binary colloidal mixture of spheres and platelets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11422-11430. [PMID: 18781779 DOI: 10.1021/la8015595] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe the phase behavior of an aqueous mixture of discotic nanoparticles of laponite and spherical magnetic nanoparticles of maghemite. To obtain stable mixtures from a chemical point of view, the maghemite nanoparticles are first coated by a thin layer of silica in order to adapt their surface chemistry to that of laponite nanoparticles: this enables one to raise volume fractions of maghemite Phi mag in the laponite suspensions up to several percent. Although the system is out of equilibrium, a "fluid-solid" state diagram was established showing that the mixtures undergo a fluid-solid transition, similar to that of pure suspensions of laponite, over a given volume fraction of laponite Phi lap and over a given Phi mag. An increase in Phi mag shifts Phi lap toward the lower values. When a solid sample is just above Phi lap, the application of an external magnetic field gradient induces a solid-to-liquid transition if the sample is located not too far from Phi lap on the state diagram. The structure of the mixtures, determined either at small scale by small-angle neutron scattering (SANS) or at intermediate scales by optical microscopy, shows that the solid samples are phase separated at a local scale: they are made of densely connected domains of laponite nanoparticles surrounding liquid pockets of maghemite nanoparticles. The size of the pockets grows with time. The magnetic liquid pockets are responsible for the rupture of the solid samples when an external magnetic field gradient is applied since their deformation induces local mechanical stress, internally damaging the network formed by the solid domains of laponite. The microscopic phase separation is the result of two opposite effects: (i) entropic effects that tend to phase separate the system macroscopically when the packing entropy overcomes the orientational entropy and (ii) long-range electrostatic repulsions that freeze the system.
Collapse
Affiliation(s)
- Fabrice Cousin
- Laboratoire Leon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif-sur-Yvette, France.
| | | | | | | |
Collapse
|