1
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Chen W, Sixdenier L, McMullen A, Grier DG, Brujic J. Refractive-index and density-matched emulsions with programmable DNA interactions. SOFT MATTER 2024; 20:4175-4183. [PMID: 38506651 DOI: 10.1039/d4sm00032c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Emulsion droplets on the colloidal length scale are a model system of frictionless compliant spheres. Direct imaging studies of the microscopic structure and dynamics of emulsions offer valuable insights into fundamental processes, such as gelation, jamming, and self-assembly. A microscope, however, can only resolve the individual droplets in a densely packed emulsion if the droplets are closely index-matched to their fluid medium. Mitigating perturbations due to gravity additionally requires the droplets to be density-matched to the medium. Creating droplets that are simultaneously index-matched and density-matched has been a long-standing challenge for the soft-matter community. The present study introduces a method for synthesizing monodisperse micrometer-sized siloxane droplets whose density and refractive index can be precisely and independently tuned by adjusting the volume fraction of three silane precursors. A systematic optimization protocol yields fluorescently labeled ternary droplets whose densities and refractive indexes match, to the fourth decimal place, those of aqueous solutions of glycerol or dimethylsiloxane. Because all of the materials in this system are biocompatible, we functionalize the droplets with DNA strands to endow them with programmed inter-droplet interactions. Confocal microscopy then reveals both the three-dimensional structure and the network of droplet-droplet contacts in a class of self-assembled droplet gels, free from gravitational effects. This experimental toolbox creates opportunities for studying the microscopic mechanisms that govern viscoelastic properties and self-assembly in soft materials.
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Affiliation(s)
- Wenjun Chen
- Center for Soft Matter Research and Department of Physics, New York University, New York, New York, 10003, USA.
| | - Lucas Sixdenier
- Center for Soft Matter Research and Department of Physics, New York University, New York, New York, 10003, USA.
| | - Angus McMullen
- Center for Soft Matter Research and Department of Physics, New York University, New York, New York, 10003, USA.
| | - David G Grier
- Center for Soft Matter Research and Department of Physics, New York University, New York, New York, 10003, USA.
| | - Jasna Brujic
- Center for Soft Matter Research and Department of Physics, New York University, New York, New York, 10003, USA.
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2
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Li J, Maazouz A, Lamnawar K. Unveiling the restricted mobility of carbon nanotubes inside a long chain branched polymer matrix via probing the shear flow effects on the rheological and electrical properties of the filled systems. SOFT MATTER 2023; 19:9146-9165. [PMID: 37990758 DOI: 10.1039/d3sm01311a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
The present work has aimed at gaining a deeper understanding of the effects of shear flow on the behaviors of nano filler evolution inside linear and long chain branched polymer matrices. Accordingly, measurements consisting of transient start-up shear rheology coupled with small amplitude oscillatory sweep (SAOS) and dielectric tests were designed. Linear polypropylene (PPC) and polypropylene (PPH) with long chain branching (LCB) were chosen as the polymer matrices and carbon nanotubes (CNTs) as the nanofillers. The percolation threshold of the LCB PPH nanocomposites was found to be higher than for linear PPC, due to the high viscosity and elasticity of LCB PPH. A transient shear with different shear rates was imposed on the composites after which SAOS and electrical conductivity measurements were conducted. The liquid-solid transitions of the nanocomposites were found to be different and to depend on the shear flow conditions (shear rate). For the linear PPC, higher shear rates caused the filler network to break down while lower shear rates helped the nanofillers to agglomerate. Interestingly, for LCB PPH, both higher and lower pre-shear rates resulted in the breakup of the filler networks, which was due to the restricted mobility of the CNTs by the LCB. The confinement of the polymer chains to the CNTs and their aggregates made it difficult for the fillers to move thus causing the formed network to be easily destroyed even under slow and slight shears. Similarly, the trend was also found after shear flows as reflected by the increase and decrease of electrical conductivities.
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Affiliation(s)
- Jixiang Li
- Univ Lyon, CNRS, UMR 5223, Ingénierie des Matériaux Polymères, INSA Lyon, Université Claude Bernard Lyon 1, Université Jean Monnet, CEDEX, F-69621 Villeurbanne, France.
| | - Abderrahim Maazouz
- Univ Lyon, CNRS, UMR 5223, Ingénierie des Matériaux Polymères, INSA Lyon, Université Claude Bernard Lyon 1, Université Jean Monnet, CEDEX, F-69621 Villeurbanne, France.
- Hassan II Academy of Science and Technology, Rabat 10100, Morocco
| | - Khalid Lamnawar
- Univ Lyon, CNRS, UMR 5223, Ingénierie des Matériaux Polymères, INSA Lyon, Université Claude Bernard Lyon 1, Université Jean Monnet, CEDEX, F-69621 Villeurbanne, France.
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3
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Pyttlik A, Kuttich B, Kraus T. Microgravity Removes Reaction Limits from Nonpolar Nanoparticle Agglomeration. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204621. [PMID: 36216735 DOI: 10.1002/smll.202204621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Gravity can affect the agglomeration of nanoparticles by changing convection and sedimentation. The temperature-induced agglomeration of hexadecanethiol-capped gold nanoparticles in microgravity (µ g) is studied at the ZARM (Center of Applied Space Technology and Microgravity) drop tower and compared to their agglomeration on the ground (1 g). Nonpolar nanoparticles with a hydrodynamic diameter of 13 nm are dispersed in tetradecane, rapidly cooled from 70 to 10 °C to induce agglomeration, and observed by dynamic light scattering at a time resolution of 1 s. The mean hydrodynamic diameters of the agglomerates formed after 8 s in microgravity are 3 times (for low initial concentrations) to 5 times (at high initial concentrations) larger than on the ground. The observations are consistent with an agglomeration process that is closer to the reaction limit on thground and closer to the diffusion limit in microgravity.
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Affiliation(s)
- Andrea Pyttlik
- Structure Formation, INM Leibniz-Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany
| | - Björn Kuttich
- Structure Formation, INM Leibniz-Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany
| | - Tobias Kraus
- Structure Formation, INM Leibniz-Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany
- Colloid and Interface Chemistry, Saarland University, Campus D2 2, 66123, Saarbrücken, Germany
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4
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Gallegos MJ, Soetrisno DD, Park N, Conrad J. Aggregation and Gelation in a Tunable Aqueous Colloid-Polymer Bridging System. J Chem Phys 2022; 157:114903. [DOI: 10.1063/5.0101697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report a colloid-polymer model system with tunable bridging interactions for microscopic studies of structure and dynamics using confocal imaging. The interactions between trifluoroethyl methacrylate-co-\emph{tert}-butyl methacrylate (TtMA) copolymer particles and poly(acrylic acid) (PAA) polymers were controllable via polymer concentration and pH. The strength of adsorption of PAA on the particle surface, driven by pH-dependent interactions with polymer brush stabilizers on the particle surfaces, was tuned via solution pH. Particle-polymer suspensions formulated at low pH, where polymers strongly adsorbed to the particles, contained clusters or weak gels at particle volume fractions of $\phi = 0.15$ and $\phi = 0.40$. At high pH, where the PAA only weakly adsorbed to the particle surface, particles largely remained dispersed and the suspensions behaved as a dense fluid. The ability to visualize suspension structure is likely to provide insight into the role of polymer-driven bridging interactions on the behavior of colloidal suspensions.
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Affiliation(s)
| | | | | | - Jacinta Conrad
- Chemical and Biomolecular Engineering, University of Houston, United States of America
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5
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Born P, Braibanti M, Cristofolini L, Cohen-Addad S, Durian DJ, Egelhaaf SU, Escobedo-Sánchez MA, Höhler R, Karapantsios TD, Langevin D, Liggieri L, Pasquet M, Rio E, Salonen A, Schröter M, Sperl M, Sütterlin R, Zuccolotto-Bernez AB. Soft matter dynamics: A versatile microgravity platform to study dynamics in soft matter. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:124503. [PMID: 34972443 DOI: 10.1063/5.0062946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
We describe an experiment container with light scattering and imaging diagnostics for experiments on soft matter aboard the International Space Station (ISS). The suite of measurement capabilities can be used to study different materials in exchangeable sample cell units. The currently available sample cell units and future possibilities for foams, granular media, and emulsions are presented in addition to an overview of the design and the diagnostics of the experiment container. First results from measurements performed on ground and during the commissioning aboard the ISS highlight the capabilities of the experiment container to study the different materials.
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Affiliation(s)
- P Born
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - M Braibanti
- HE Space Operations BV for ESA, NL-2200AG Noordwijk, The Netherlands
| | - L Cristofolini
- CNR - Institute of Condensed Matter Chemistry and Technologies for Energy Unit of Genoa, 16149 Genova, Italy
| | - S Cohen-Addad
- Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris, France
| | - D J Durian
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - S U Egelhaaf
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - M A Escobedo-Sánchez
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - R Höhler
- Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris, France
| | - T D Karapantsios
- Department of Chemical Technology, School of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - D Langevin
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université de Paris Saclay, 91405 Orsay, France
| | - L Liggieri
- CNR - Institute of Condensed Matter Chemistry and Technologies for Energy Unit of Genoa, 16149 Genova, Italy
| | - M Pasquet
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université de Paris Saclay, 91405 Orsay, France
| | - E Rio
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université de Paris Saclay, 91405 Orsay, France
| | - A Salonen
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université de Paris Saclay, 91405 Orsay, France
| | - M Schröter
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - M Sperl
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - R Sütterlin
- Department TESXS Science Systems Engineering, Airbus Defence and Space, Claude Dornier Str., 88090 Immenstaad, Germany
| | - A B Zuccolotto-Bernez
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
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6
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Royall CP, Faers MA, Fussell SL, Hallett JE. Real space analysis of colloidal gels: triumphs, challenges and future directions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:453002. [PMID: 34034239 DOI: 10.1088/1361-648x/ac04cb] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Colloidal gels constitute an important class of materials found in many contexts and with a wide range of applications. Yet as matter far from equilibrium, gels exhibit a variety of time-dependent behaviours, which can be perplexing, such as an increase in strength prior to catastrophic failure. Remarkably, such complex phenomena are faithfully captured by an extremely simple model-'sticky spheres'. Here we review progress in our understanding of colloidal gels made through the use of real space analysis and particle resolved studies. We consider the challenges of obtaining a suitable experimental system where the refractive index and density of the colloidal particles is matched to that of the solvent. We review work to obtain a particle-level mechanism for rigidity in gels and the evolution of our understanding of time-dependent behaviour, from early-time aggregation to ageing, before considering the response of colloidal gels to deformation and then move on to more complex systems of anisotropic particles and mixtures. Finally we note some more exotic materials with similar properties.
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Affiliation(s)
- C Patrick Royall
- Gulliver UMR CNRS 7083, ESPCI Paris, Université PSL, 75005 Paris, France
- HH Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom
- School of Chemistry, University of Bristol, Cantock Close, Bristol, BS8 1TS, United Kingdom
- Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol, BS8 1FD, United Kingdom
| | - Malcolm A Faers
- Bayer AG, Crop Science Division, Formulation Technology, Alfred Nobel Str. 50, 40789 Monheim, Germany
| | - Sian L Fussell
- School of Chemistry, University of Bristol, Cantock Close, Bristol, BS8 1TS, United Kingdom
- Bristol Centre for Functional Nanomaterials, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom
| | - James E Hallett
- Physical and Theoretical Chemistry Laboratory, South Parks Road, University of Oxford, OX1 3QZ, United Kingdom
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7
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Exploration of space to achieve scientific breakthroughs. Biotechnol Adv 2020; 43:107572. [PMID: 32540473 DOI: 10.1016/j.biotechadv.2020.107572] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/05/2020] [Accepted: 05/29/2020] [Indexed: 12/13/2022]
Abstract
Living organisms adapt to changing environments using their amazing flexibility to remodel themselves by a process called evolution. Environmental stress causes selective pressure and is associated with genetic and phenotypic shifts for better modifications, maintenance, and functioning of organismal systems. The natural evolution process can be used in complement to rational strain engineering for the development of desired traits or phenotypes as well as for the production of novel biomaterials through the imposition of one or more selective pressures. Space provides a unique environment of stressors (e.g., weightlessness and high radiation) that organisms have never experienced on Earth. Cells in the outer space reorganize and develop or activate a range of molecular responses that lead to changes in cellular properties. Exposure of cells to the outer space will lead to the development of novel variants more efficiently than on Earth. For instance, natural crop varieties can be generated with higher nutrition value, yield, and improved features, such as resistance against high and low temperatures, salt stress, and microbial and pest attacks. The review summarizes the literature on the parameters of outer space that affect the growth and behavior of cells and organisms as well as complex colloidal systems. We illustrate an understanding of gravity-related basic biological mechanisms and enlighten the possibility to explore the outer space environment for application-oriented aspects. This will stimulate biological research in the pursuit of innovative approaches for the future of agriculture and health on Earth.
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8
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Nguyen HT, Graham AL, Koenig PH, Gelb LD. Computer simulations of colloidal gels: how hindered particle rotation affects structure and rheology. SOFT MATTER 2020; 16:256-269. [PMID: 31782472 DOI: 10.1039/c9sm01755k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The effects of particle roughness and short-ranged non-central forces on colloidal gels are studied using computer simulations in which particles experience a sinusoidal variation in energy as they rotate. The number of minima n and energy scale K are the key parameters; for large K and n, particle rotation is strongly hindered, but for small K and n particle rotation is nearly free. A series of systems are simulated and characterized using fractal dimensions, structure factors, coordination number distributions, bond-angle distributions and linear rheology. When particles rotate easily, clusters restructure to favor dense packings. This leads to longer gelation times and gels with strand-like morphology. The elastic moduli of such gels scale as G'∝ω0.5 at high shear frequencies ω. In contrast, hindered particle rotation inhibits restructuring and leads to rapid gelation and diffuse morphology. Such gels are stiffer, with G'∝ω0.35. The viscous moduli G'' in the low-barrier and high-barrier regimes scale according to exponents 0.53 and 0.5, respectively. The crossover frequency between elastic and viscous behaviors generally increases with the barrier to rotation. These findings agree qualitatively with some recent experiments on heterogeneously-surface particles and with studies of DLCA-type gels and gels of smooth spheres.
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Affiliation(s)
- Hong T Nguyen
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, USA.
| | - Alan L Graham
- Department of Mechanical Engineering, University of Colorado - Denver, Denver, CO, USA
| | - Peter H Koenig
- Beauty Care Modeling and Simulation, Mason Business Center, 8700 Mason-Montgomery Rd, Mason, OH 45040, USA
| | - Lev D Gelb
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, USA.
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9
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Silva KL, Silmi L, Brock SL. Effect of metal ion solubility on the oxidative assembly of metal sulfide quantum dots. J Chem Phys 2019; 151:234715. [PMID: 31864264 DOI: 10.1063/1.5128932] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The versatility of the oxidative assembly method for the creation of 2D and 3D quantum dot (QD) architectures represents both an opportunity and a challenge as a method enabling controlled placement of chemically distinct QDs in multicomponent systems. The opportunity lies in the ability to independently tune the kinetics of the different components so that they are similar (leading to well-mixed systems) or different (enabling gradient or phase-segregated composites) using a wide range of variables; the challenge lies in understanding those variables and how their interplay affects the overall kinetics. Here, we show that the identity of the cation in the sulfide matrix (M = Cd2+ vs Zn2+) plays a large role in the kinetics of assembly of mass spectrometry QDs, attributed to differences in solubility. Time resolved dynamic light scattering is used to monitor the hydrodynamic radius, R¯h. ZnS shows an exponential growth associated with reaction-limited cluster aggregation (RLCA), whereas CdS demonstrates a significant induction period (10-75 min) followed by a growth step that cannot be distinguished between RLCA and diffusion limited cluster aggregation. These data correlate with relative solubilities of the nanoparticles, as probed by free-cation concentration. Data also confirm prior studies showing that cubic-closest-packed (ccp) lattices are kinetically slow relative to hexagonally closest-packed (hcp); using the slope of the ln R¯h vs time plot for the rate constant, the values of 0.510 s-1 and 3.92 s-1 are obtained for ccp ZnS and hcp ZnS, respectively. Thus, both the structure and the solubility are effective levers for adjusting the relative reactivity of QDs toward oxidative assembly.
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Affiliation(s)
- Karunamuni L Silva
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Leenah Silmi
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Stephanie L Brock
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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10
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Amselem S. Remote Controlled Autonomous Microgravity Lab Platforms for Drug Research in Space. Pharm Res 2019; 36:183. [PMID: 31741058 DOI: 10.1007/s11095-019-2703-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/13/2019] [Indexed: 12/23/2022]
Abstract
Research conducted in microgravity conditions has the potential to yield new therapeutics, as advances can be achieved in the absence of phenomena such as sedimentation, hydrostatic pressure and thermally-induced convection. The outcomes of such studies can significantly contribute to many scientific and technological fields, including drug discovery. This article reviews the existing traditional microgravity platforms as well as emerging ideas for enabling microgravity research focusing on SpacePharma's innovative autonomous remote-controlled microgravity labs that can be launched to space aboard nanosatellites to perform drug research in orbit. The scientific literature is reviewed and examples of life science fields that have benefited from studies in microgravity conditions are given. These include the use of microgravity environment for chemical applications (protein crystallization, drug polymorphism, self-assembly of biomolecules), pharmaceutical studies (microencapsulation, drug delivery systems, behavior and stability of colloidal formulations, antibiotic drug resistance), and biological research, including accelerated models for aging, investigation of bacterial virulence , tissue engineering using organ-on-chips in space, enhanced stem cells proliferation and differentiation.
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Affiliation(s)
- Shimon Amselem
- SpacePharma R&D Israel LTD, 1st Aba Even Av, 4672519, Herzliya Pituach, Israel. .,SpacePharma SA, Rue l'Armeratte 3, 2950, Courgenay, Switzerland.
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11
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Light scattering studies of the sol-to-gel transition in particulate systems. J Colloid Interface Sci 2019; 556:577-583. [DOI: 10.1016/j.jcis.2019.08.075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/19/2019] [Accepted: 08/20/2019] [Indexed: 11/24/2022]
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12
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Zhang S, Zhang L, Bouzid M, Rocklin DZ, Del Gado E, Mao X. Correlated Rigidity Percolation and Colloidal Gels. PHYSICAL REVIEW LETTERS 2019; 123:058001. [PMID: 31491284 DOI: 10.1103/physrevlett.123.058001] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 05/25/2023]
Abstract
Rigidity percolation (RP) occurs when mechanical stability emerges in disordered networks as constraints or components are added. Here we discuss RP with structural correlations, an effect ignored in classical theories albeit relevant to many liquid-to-amorphous-solid transitions, such as colloidal gelation, which are due to attractive interactions and aggregation. Using a lattice model, we show that structural correlations shift RP to lower volume fractions. Through molecular dynamics simulations, we show that increasing attraction in colloidal gelation increases structural correlation and thus lowers the RP transition, agreeing with experiments. Hence, the emergence of rigidity at colloidal gelation can be understood as a RP transition, but occurs at volume fractions far below values predicted by the classical RP, due to attractive interactions which induce structural correlation.
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Affiliation(s)
- Shang Zhang
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Leyou Zhang
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Mehdi Bouzid
- Department of Physics, Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, D.C. 20057, USA
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - D Zeb Rocklin
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Emanuela Del Gado
- Department of Physics, Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, D.C. 20057, USA
| | - Xiaoming Mao
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
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13
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Ferrar JA, Pavlovsky L, Viges E, Liu Y, Solomon MJ. Two‐step continuous production of monodisperse colloidal ellipsoids at rates of one gram per day. AIChE J 2017. [DOI: 10.1002/aic.16009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Joseph A. Ferrar
- Dept. of Chemical EngineeringUniversity of MichiganAnn Arbor MI 48109
| | - Leonid Pavlovsky
- Dept. of Chemical EngineeringUniversity of MichiganAnn Arbor MI 48109
| | - Eric Viges
- Dept. of Chemical EngineeringUniversity of MichiganAnn Arbor MI 48109
| | - Yanliang Liu
- Dept. of Macromolecular Science and EngineeringUniversity of MichiganAnn Arbor MI 48109
| | - Michael J. Solomon
- Dept. of Chemical EngineeringUniversity of MichiganAnn Arbor MI 48109
- Dept. of Macromolecular Science and EngineeringUniversity of MichiganAnn Arbor MI 48109
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14
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Griffiths S, Turci F, Royall CP. Local structure of percolating gels at very low volume fractions. J Chem Phys 2017; 146:014905. [DOI: 10.1063/1.4973351] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Yang Z, Hemar Y, Hilliou L, Gilbert EP, McGillivray DJ, Williams MAK, Chaieb S. Nonlinear Behavior of Gelatin Networks Reveals a Hierarchical Structure. Biomacromolecules 2015; 17:590-600. [DOI: 10.1021/acs.biomac.5b01538] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Zhi Yang
- School
of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Yacine Hemar
- School
of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Institute
of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
- The Riddet Institute, Palmerston North 4442, New Zealand
| | - Loic Hilliou
- Institute
for Polymers and Composites/I3N, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
| | - Elliot P. Gilbert
- Bragg
Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Duncan J. McGillivray
- School
of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Institute
of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
- The MacDiarmid Institute, Palmerston
North 4442, New Zealand
| | - Martin A. K. Williams
- Institute
of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
- The Riddet Institute, Palmerston North 4442, New Zealand
- The MacDiarmid Institute, Palmerston
North 4442, New Zealand
| | - Sahraoui Chaieb
- Division
of Physical Sciences and Engineering, King Abdullah University of Sciences and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
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16
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Godfrin MP, Tiwari A, Bose A, Tripathi A. Phase and steady shear behavior of dilute carbon black suspensions and carbon black stabilized emulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:15400-15407. [PMID: 25469772 DOI: 10.1021/la504151z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use para-amino benzoic acid terminated carbon black (CB) as a model particulate material to study the effect of salt-modulated attractive interactions on phase behavior and steady shear stresses in suspensions and particle-stabilized emulsions. Surprisingly, the suspension displayed a yield stress at a CB volume fraction of ϕCB = 0.008. The yield stress scaled with CB concentration with power law behavior; the power law exponent changed abruptly at a critical CB concentration, suggesting a substantial change in network structure. Cryogenic scanning electron microscopy revealed structural differences between the networks found in each scaling regime. Randomly oriented pores with thick CB boundaries were observed in the scaling region above the critical particle concentration, suggesting a strong gel network, and long, oriented pores were found in the scaling region below the critical particle concentration, suggesting a weak network influenced by an induced shear stress. These findings correlate with the existence of gels and transient networks. Transient networks break down under gravitational forces over time periods of 12-24 hours. The yield stresses of CB-gels containing oil emulsion droplets were found to scale with carbon black concentration similar to the CB-gels without oil. These results offer insight into salt-induced attractive colloidal networks and the difference in structure and yield-stress behavior between transient networks and gels. Furthermore, CB offers the ability to stabilize an oil phase in discrete droplets and contain them within a rigid network structure.
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Affiliation(s)
- Michael P Godfrin
- Center for Biomedical Engineering, School of Engineering, Brown University , Providence, Rhode Island 02912, United States
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17
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Legg BA, Zhu M, Comolli LR, Gilbert B, Banfield JF. Impacts of ionic strength on three-dimensional nanoparticle aggregate structure and consequences for environmental transport and deposition. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:13703-13710. [PMID: 25380400 DOI: 10.1021/es502654q] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The transport of nanoparticles through aqueous systems is a complex process with important environmental policy ramifications. Ferrihydrite nanoparticles commonly form aggregates, with structures that depend upon solution chemistry. The impact of aggregation state on transport and deposition is not fully understood. In this study, small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were used to directly observe the aggregate structure of ferrihydrite nanoparticles and show how the aggregate structure responds to changing ionic strength. These results were correlated with complementary studies on ferrihydrite transport through saturated quartz sand columns. Within deionized water, nanoparticles form stable suspensions of low-density fractal aggregates that are resistant to collapse. The particles subsequently show limited deposition on sand grain surfaces. Within sodium nitrate solutions the aggregates collapse into denser clusters, and nanoparticle deposition increases dramatically by forming thick, localized, and mechanically unstable deposits. Such deposits limit nanoparticle transport and make transport less predictable. The action of ionic strength is distinct from simpler models of colloidal stability and transport, in that salt not only drives aggregation or attachment but also alters the behavior of preexisting aggregates by triggering their collapse.
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Affiliation(s)
- Benjamin A Legg
- Department of Earth and Planetary Science, University of California , Berkeley, California 94720, United States
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Legg BA, Zhu M, Comolli LR, Gilbert B, Banfield JF. Determination of the three-dimensional structure of ferrihydrite nanoparticle aggregates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9931-9940. [PMID: 25079430 DOI: 10.1021/la502128d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Aggregation impacts the reactivity, colloidal stability, and transport behavior of nanomaterials, yet methods to characterize basic structural features of aggregates are limited. Here, cryo-transmission electron microscope (cryo-TEM) based tomography is utilized as a method for directly imaging fragile aggregates of nanoparticles in aqueous suspension and an approach for extracting quantitative fractal dimensions from the resulting three-dimensional structural models is introduced. The structural quantification approach is based upon the mass autocorrelation function, and is directly comparable with small-angle X-ray scattering (SAXS) models. This enables accurate characterization of aggregate structure, even in suspensions where the aggregate cluster size is highly polydisperse and traditional SAXS modeling is not reliable. This technique is applied to study real suspensions of ferrihydrite nanoparticles. By comparing tomographic measurements with SAXS-based measurements, we infer that certain suspensions contain polydisperse aggregate size distributions. In other suspensions, fractal-type structures are identified with low intrinsic fractal dimensions. The fractal dimensions are lower than would be predicted by simple models of particle aggregation, and this low dimensionality enables large, low-density aggregates to exist in stable colloidal suspension.
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Affiliation(s)
- Benjamin A Legg
- Earth and Planetary Science, University of California-Berkeley , Berkeley, California 94720, United States
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19
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Nigro B, Grimaldi C, Ryser P, Varrato F, Foffi G, Lu PJ. Enhanced tunneling conductivity induced by gelation of attractive colloids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:062312. [PMID: 23848680 DOI: 10.1103/physreve.87.062312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 04/04/2013] [Indexed: 06/02/2023]
Abstract
We show that the formation of a gel by conducting colloidal particles leads to a dramatic enhancement in bulk conductivity, due to interparticle electron tunneling, combining predictions from molecular-dynamics simulations with structural measurements in an experimental colloid system. Our results show how colloidal gelation can be used as a general route to huge enhancements of conductivity, and suggest a feasible way for developing cheap materials with novel properties and low metal content.
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Affiliation(s)
- Biagio Nigro
- LPM, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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20
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Eleftheriou E, Karatasos K. Modeling the formation of ordered nano-assemblies comprised by dendrimers and linear polyelectrolytes: the role of Coulombic interactions. J Chem Phys 2013; 137:144905. [PMID: 23061863 DOI: 10.1063/1.4757666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Models of mixtures of peripherally charged dendrimers with oppositely charged linear polyelectrolytes in the presence of explicit solvent are studied by means of molecular dynamics simulations. Under the influence of varying strength of electrostatic interactions, these systems appear to form dynamically arrested film-like interconnected structures in the polymer-rich phase. Acting like a pseudo-thermodynamic inverse temperature, the increase of the strength of the Coulombic interactions drive the polymeric constituents of the mixture to a gradual dynamic freezing-in. The timescale of the average density fluctuations of the formed complexes initially increases in the weak electrostatic regime reaching a finite limit as the strength of electrostatic interactions grow. Although the models are overall electrically neutral, during this process the dendrimer/linear complexes develop a polar character with an excess charge mainly close to the periphery of the dendrimers. The morphological characteristics of the resulted pattern are found to depend on the size of the polymer chains on account of the distinct conformational features assumed by the complexed linear polyelectrolytes of different length. In addition, the length of the polymer chain appears to affect the dynamics of the counterions, thus affecting the ionic transport properties of the system. It appears, therefore, that the strength of electrostatic interactions together with the length of the linear polyelectrolytes are parameters to which these systems are particularly responsive, offering thus the possibility for a better control of the resulted structure and the electric properties of these soft-colloidal systems.
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Affiliation(s)
- E Eleftheriou
- Physical Chemistry Laboratory, Chemical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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21
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Nanoemulsion stability: experimental evaluation of the flocculation rate from turbidity measurements. Adv Colloid Interface Sci 2012; 178:1-20. [PMID: 22657245 DOI: 10.1016/j.cis.2012.05.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 02/14/2012] [Accepted: 05/01/2012] [Indexed: 11/20/2022]
Abstract
The coalescence of liquid drops induces a higher level of complexity compared to the classical studies about the aggregation of solid spheres. Yet, it is commonly believed that most findings on solid dispersions are directly applicable to liquid mixtures. Here, the state of the art in the evaluation of the flocculation rate of these two systems is reviewed. Special emphasis is made on the differences between suspensions and emulsions. In the case of suspensions, the stability ratio is commonly evaluated from the initial slope of the absorbance as a function of time under diffusive and reactive conditions. Puertas and de las Nieves (1997) developed a theoretical approach that allows the determination of the flocculation rate from the variation of the turbidity of a sample as a function of time. Here, suitable modifications of the experimental procedure and the referred theoretical approach are implemented in order to calculate the values of the stability ratio and the flocculation rate corresponding to a dodecane-in-water nanoemulsion stabilized with sodium dodecyl sulfate. Four analytical expressions of the turbidity are tested, basically differing in the optical cross section of the aggregates formed. The first two models consider the processes of: a) aggregation (as described by Smoluchowski) and b) the instantaneous coalescence upon flocculation. The other two models account for the simultaneous occurrence of flocculation and coalescence. The latter reproduce the temporal variation of the turbidity in all cases studied (380≤[NaCl]≤600 mM), providing a method of appraisal of the flocculation rate in nanoemulsions.
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22
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Eberle APR, Castañeda-Priego R, Kim JM, Wagner NJ. Dynamical arrest, percolation, gelation, and glass formation in model nanoparticle dispersions with thermoreversible adhesive interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:1866-1878. [PMID: 22148874 DOI: 10.1021/la2035054] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report an experimental study of the dynamical arrest transition for a model system consisting of octadecyl coated silica suspended in n-tetradecane from dilute to concentrated conditions spanning the state diagram. The dispersion's interparticle potential is tuned by temperature affecting the brush conformation leading to a thermoreversible model system. The critical temperature for dynamical arrest, T*, is determined as a function of dispersion volume fraction by small-amplitude dynamic oscillatory shear rheology. We corroborate this transition temperature by measuring a power-law decay of the autocorrelation function and a loss of ergodicity via fiber-optic quasi-elastic light scattering. The structure at T* is measured using small-angle neutron scattering. The scattering intensity is fit to extract the interparticle pair-potential using the Ornstein-Zernike equation with the Percus-Yevick closure approximation, assuming a square-well interaction potential with a short-range interaction (1% of particle diameter). (1) The strength of attraction is characterized using the Baxter temperature (2) and mapped onto the adhesive hard sphere state diagram. The experiments show a continuous dynamical arrest transition line that follows the predicted dynamical percolation line until ϕ ≈ 0.41 where it subtends the predictions toward the mode coupling theory attractive-driven glass line. An alternative analysis of the phase transition through the reduced second virial coefficient B(2)* shows a change in the functional dependence of B(2)* on particle concentration around ϕ ≈ 0.36. We propose this signifies the location of a gel-to-glass transition. The results presented herein differ from those observed for depletion flocculated dispersion of micrometer-sized particles in polymer solutions, where dynamical arrest is a consequence of multicomponent phase separation, suggesting dynamical arrest is sensitive to the physical mechanism of attraction.
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Affiliation(s)
- Aaron P R Eberle
- Center for Neutron Science, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, United States
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23
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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.
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Affiliation(s)
- S Santinath Singh
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India.
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24
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Huh JY, Lynch ML, Furst EM. Poroelastic Consolidation in the Phase Separation of Vesicle−Polymer Suspensions. Ind Eng Chem Res 2010. [DOI: 10.1021/ie1004543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ji Yeon Huh
- Department of Chemical Engineering and Center for Molecular and Engineering Thermodynamics, University of Delaware, Colburn Laboratory, 150 Academy Street, Newark, Delaware 19716, and The Procter and Gamble Company, 8256 Union Centre Boulevard, CP-426 West Chester, Ohio 45069
| | - Matthew L. Lynch
- Department of Chemical Engineering and Center for Molecular and Engineering Thermodynamics, University of Delaware, Colburn Laboratory, 150 Academy Street, Newark, Delaware 19716, and The Procter and Gamble Company, 8256 Union Centre Boulevard, CP-426 West Chester, Ohio 45069
| | - Eric M. Furst
- Department of Chemical Engineering and Center for Molecular and Engineering Thermodynamics, University of Delaware, Colburn Laboratory, 150 Academy Street, Newark, Delaware 19716, and The Procter and Gamble Company, 8256 Union Centre Boulevard, CP-426 West Chester, Ohio 45069
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25
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Yuan X, Schnell M, Muth S, Schärtl W. Cluster formation and rheology of photoreactive nanoparticle dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:5299-5305. [PMID: 18433151 DOI: 10.1021/la800043j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We show how photocrosslinking of small nanoparticles within a very dilute colloidal dispersion leads to the formation of large fractal particle clusters, which have a strong influence on the viscosity of the dispersion although the overall solid content is well below 5 wt %. Furthermore, the solvent plays an important role because of its function as an optical filter, for example, in toluene only photocrosslinking but no photocleavage takes place. Therefore, a diffusion-controlled cluster growth mechanism, leading to clusters with low fractal dimension, is expected; on the other hand, in tetrahydrofuran the photoreaction is partially reversible. Therefore, the cluster growth in this case is reaction controlled, leading to more compact clusters with higher fractal dimension, which therefore only have a negligible effect on the rheological properties of the solvent. In this context, we will briefly discuss the possibility to use our nanoparticle system as opto-rheological switch.
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Affiliation(s)
- Xiaofeng Yuan
- Institut für Physikalische Chemie, Johannes-Gutenberg-Universität Mainz, Germany
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26
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Romero-Cano MS, Puertas AM. Phase behaviour of a model colloid-polymer mixture at low colloid concentration. SOFT MATTER 2008; 4:1242-1248. [PMID: 32907268 DOI: 10.1039/b801640b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The phase behaviour of a colloid-polymer mixture is studied at very low colloid concentrations (below 0.5%). The size ratio between the polymer and the colloidal particles is around 0.09, so that the colloids experience short-range attractions. At these low volume fractions, fluid-crystal coexistence is found at moderate polymer concentrations and the kinetics of crystallization are analyzed by turbidimetry. At higher polymer concentrations, clustering of the particles occurs, but some of them remain in a diluted, gas, phase composed mainly of single particles. These states do not correspond to vapor-liquid coexistence, as shown by studying the density of the gas phase. Strong interactions induce flocculation of the system, producing fractal aggregates with dimension df ≈ 1.8, compatible with diffusion limited cluster aggregation (DLCA). These results are discussed in connection with the phase diagram of colloid-polymer mixtures, obtained at much higher colloid concentrations. For low colloid volume fractions, below ∼0.05%, no clustering of the particles is observed for any polymer concentration.
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Affiliation(s)
- Manuel S Romero-Cano
- Grupo de Física de Fluidos Complejos, Departamento de Física Aplicada, Universidad de Almería, 04120, Andalucía, Spain
| | - Antonio M Puertas
- Grupo de Física de Fluidos Complejos, Departamento de Física Aplicada, Universidad de Almería, 04120, Andalucía, Spain
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27
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Møller PCF, Rodts S, Michels MAJ, Bonn D. Shear banding and yield stress in soft glassy materials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:041507. [PMID: 18517628 DOI: 10.1103/physreve.77.041507] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Indexed: 05/26/2023]
Abstract
Shear localization is a generic feature of flows in yield stress fluids and soft glassy materials but is incompletely understood. In the classical picture of yield stress fluids, shear banding happens because of a stress heterogeneity. Using recent developments in magnetic resonance imaging velocimetry, we show here for a colloidal gel that even in a homogeneous stress situation shear banding occurs, and that the width of the flowing band is uniquely determined by the macroscopically imposed shear rate rather than the stress. We present a simple physical model for flow of the gel showing that shear banding (localization) is a flow instability that is intrinsic to the material, and confirm the model predictions for our system using rheology and light scattering.
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Affiliation(s)
- P C F Møller
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris, F-75231 France
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28
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Kätzel U, Richter T, Stintz M, Barthel H, Gottschalk-Gaudig T. Phase transitions of pyrogenic silica suspensions: a comparison to model laponite. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:031402. [PMID: 17930242 DOI: 10.1103/physreve.76.031402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 06/18/2007] [Indexed: 05/25/2023]
Abstract
Pyrogenic silica is often used as a thickening agent in paints, pastes, adhesives, or resins. Other applications include, e.g., abrasives in chemical mechanical planarization in the microelectronics industry. In all these applications it is essential to control the state of dispersion. Sometimes, phase transitions from the liquid to the solid state are required while in other cases they have to be completely avoided for the whole shelf life. The nature and influencing parameters of the fluid-solid transition for pyrogenic silica have not been investigated so far. Most investigations deal with the phase transitions of small clay particles such as laponite. Here, we dedicate our interest to the behavior of pyrogenic silica suspensions with varying specific surface area and ionic background concentration. To get an impression of the phase transition behavior we compare our results to model laponite suspensions. We apply dynamic light scattering measurements in the backscattering regime to minimize multiple scattering contributions from concentrated pyrogenic silica suspensions. Further on we exert a decomposition of the measured autocorrelation functions into an ergodic and nonergodic contribution. The analysis of the ergodic spectrum yields two different gelation kinetics for both systems, laponite and pyrogenic silica. For laponite these are in accordance with earlier investigations. The kinetics depend on the ionic background and the solids content of the suspensions. Additionally, we used dynamic extinction spectroscopy to follow the phase transitions of pyrogenic silica on a macroscale.
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Affiliation(s)
- Uwe Kätzel
- Research Group Mechanical Process Engineering, Institute of Process Engineering and Environmental Technology, TU Dresden, D-01062 Dresden, Germany
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29
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Sun Y, Harris NC, Kiang CH. Phase Transition and Optical Properties of DNA-Gold Nanoparticle Assemblies. PLASMONICS (NORWELL, MASS.) 2007; 2:193-199. [PMID: 19633725 PMCID: PMC2714644 DOI: 10.1007/s11468-007-9034-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We review recent work on DNA-linked gold nanoparticle assemblies. The synthesis, properties, and phase behavior of such DNA-gold nanoparticle assemblies are described. These nanoparticle assemblies have strong optical extinction in the ultraviolet and visible light regions; hence, the technique is used to study the kinetics and phase transitions of DNA-gold nanoparticle assemblies. The melting transition of DNA-gold nanoparticle assemblies shows unusual trends compared to those of free DNA. The phase transitions are influenced by many parameters, such as nanoparticle size, DNA sequence, DNA grafting density, DNA linker length, interparticle distance, base pairing defects, and disorders. The physics of the DNA-gold nanoparticle assemblies can be understood in terms of the phase behavior of complex fluids, with the colloidal gold interaction potential dominated by DNA hybridization energies.
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Affiliation(s)
- Young Sun
- Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
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30
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Zhang J, Luan L, Zhu W, Liu S, Sun D. Phase behavior of aqueous suspensions of Mg(2)Al layered double hydroxide: the competition among nematic ordering, sedimentation, and gelation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:5331-7. [PMID: 17439162 DOI: 10.1021/la0625300] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Birefringence observations and rheological measurements were used to monitor the phase behavior of Mg/Al (the molar ratio of Mg(2+) to Al(3+) being 2:1) layered double hydroxide (LDH) suspensions. The suspensions of concentration lower than 16% (w/w) appear isotropic (I) between crossed polarizers. In contrast, the suspensions of concentration between 16% and 30% (w/w) showed an isotropic (I)-nematic (N) biphasic coexistence. Detailed observations led us to divide the suspensions in the gap into three groups according to their behaviors: the suspensions with concentration between 16% and 25% (w/w) experienced an I-N phase transition and particle sedimentation simultaneously, while the suspensions of 25% to 27% (w/w) showed I-N transition after particle sedimentation, and in the suspension of 30% (w/w), a critical sol-gel transition appeared with an I-N transition. Above 33% (w/w), the gel network hindered a complete I-N separation in the suspensions. Upon raising the NaCl concentration, the liquid crystalline phase transition and the sol-gel transition shifted to higher particle concentrations. The facts demonstrate that the phase behavior of aqueous LDH suspensions is controlled by the competition among liquid crystal phase transition, sedimentation, and gelation.
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Affiliation(s)
- Jie Zhang
- Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, 250100, Shandong, P. R. China
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31
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Ohira K, Sato M, Kohmoto M. Fluctuations in chemical gelation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:041402. [PMID: 17500889 DOI: 10.1103/physreve.75.041402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 02/26/2007] [Indexed: 05/15/2023]
Abstract
We study a chemical gelation model in two dimensions which includes both monomer aggregations and bond fluctuations. Our numerical simulation shows that a sol-gel transition occurs when an initial monomer concentration is above a critical concentration. Fractal aggregates grow until the sol-gel transition occurs. After the gelation, however, bond fluctuations break the fractal structure and an interesting inhomogeneous gel fiber network appears instead. A pore size distribution of the inhomogeneous structure shows the existence of hierarchical structures in the gel phase. It is also found that slow dynamics appear near the critical concentration.
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Affiliation(s)
- Kenji Ohira
- The Institute for Solid State Physics, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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32
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Mayama H, Tsujii K. Menger sponge-like fractal body created by a novel template method. J Chem Phys 2006; 125:124706. [PMID: 17014199 DOI: 10.1063/1.2336200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have established experimental strategies on how to create a Menger sponge-like fractal body and how to control its fractal dimension. The essence was to utilize alkylketene dimer (AKD), which spontaneously forms super-water-repellent fractal surface. We prepared "fractal AKD particles" with fractal surface structure as templates of pores in fractal body. The fractal body was synthesized by filling the remained space between the packed template particles with a tetramethyl orthosilicate solution, solidifying it by the sol-gel process, and removing the template by calcinations. We have succeeded in systematically creating fractal bodies of silica with different cross-sectional fractal dimensions D(cs)=1.87, 1.84, and 1.80 using "fractal template particles" compressed under the ratio=1.0, 2.0, and 3.0, respectively. We also discussed the possibilities of their fractal geometries in comparison with mathematical models. We concluded that the created fractal bodies were close to a Menger sponge and its modified one. Our experimental strategy allows us to design fractality of porous materials.
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Affiliation(s)
- H Mayama
- Nanotechnology Research Center, Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan.
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Smith WE, Zukoski CF. Aggregation and gelation kinetics of fumed silica-ethanol suspensions. J Colloid Interface Sci 2006; 304:359-69. [PMID: 17034807 DOI: 10.1016/j.jcis.2006.09.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Revised: 08/11/2006] [Accepted: 09/09/2006] [Indexed: 11/21/2022]
Abstract
The kinetics of aggregation and gelation of fumed silica suspended in ethanol were investigated as a function of volume fraction. At low particle concentrations, gelation is well described by aggregation into a primary minimum arising from hydrogen bonding and dispersion forces. The gelation is extremely slow due to an energetic barrier (approximately 25 kT) in the interparticle potential associated with solvation forces. The solvation forces also contribute to the formation of a secondary minimum in the interparticle potential. The depth of this minimum (approximately 3 kT) is sufficient that, at a critical particle concentration, long-range diffusion is arrested due to the short-range attractions and the cooperative nature of particle interactions, as described by mode coupling theory. The presence of the secondary minimum is also observed in the microstructure of the gels studied using X-ray scattering. These observations reinforce the importance of understanding the role of solvent-particle interactions in manipulating suspension properties.
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Affiliation(s)
- William E Smith
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Schantz Zackrisson A, Martinelli A, Matic A, Bergenholtz J. Concentration effects on irreversible colloid cluster aggregation and gelation of silica dispersions. J Colloid Interface Sci 2006; 301:137-44. [PMID: 16723134 DOI: 10.1016/j.jcis.2006.04.066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 04/18/2006] [Accepted: 04/20/2006] [Indexed: 11/17/2022]
Abstract
Effects of particle concentration on the irreversible aggregation of colloidal silica are studied using in situ destabilization via the ionic strength increase derived from the enzymatic hydrolysis of urea by urease. Aggregation is monitored by time-resolved optical density and dynamic light scattering measurements. It terminates at a gel boundary, signaled by a prominent increase of the optical density and incipient non-ergodicity. Raman scattering is used to demonstrate that the enzymatic reaction continues, well beyond gelation for the compositions studied here, until the urea is consumed. Calibration of the ionic conductivity permits for constructing stability diagrams in terms of particle and salt concentration. As with reversible gelation, the process exhibits a collective character in that lower ionic strengths are required for gelation of concentrated dispersions and vice versa. However, light scattering demonstrates that the gel boundary is preceded here by a line marking the transition from reversible to irreversible cluster formation, with the two transition boundaries tracking each other. Comparisons are made with dispersions destabilized by direct addition of salt solutions, which gel under very different conditions.
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35
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Lee MH, Furst EM. Formation and evolution of sediment layers in an aggregating colloidal suspension. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:031401. [PMID: 17025629 DOI: 10.1103/physreve.74.031401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 05/30/2006] [Indexed: 05/12/2023]
Abstract
The coupled aggregation and sedimentation of colloidal particles with short-range attractions are investigated. Nonadsorbing polymer is used to induce depletion interactions between the hard-sphere particles. Gravitational forces, caused by a density mismatch between the particles and the suspending fluid, result in the sedimentation of particles and aggregates, as well as the compaction and rearrangement of the final sediment layer. At low polymer concentrations CP, or low initial volume fractions phio, clusters formed during the period of fast sedimentation are small, and the structure of the final sediment is dense. Conversely, at high CP, or high phio, large clusters form during sedimentation, and the resulting sediment structure is significantly less dense, with large void volumes. The size of the presediment aggregates depends on CP and phio with a functional form that resembles other thermally activated barrier hopping processes in colloidal systems, such as the delayed sedimentation of colloidal gels. Finally, when the particles are weakly attractive, gravitational stresses are found to induce compaction of the sediment over long periods of time. However, sediments composed of particles that are strongly attractive resist rearrangements and compaction, even when the sediment layers have a relatively large amount of free volume.
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Affiliation(s)
- Myung Han Lee
- Department of Chemical Engineering, University of Delaware, Colburn Laboratory, 150 Academy Street, Newark, Delaware 19716, USA
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Roke S, Berg O, Buitenhuis J, van Blaaderen A, Bonn M. Surface molecular view of colloidal gelation. Proc Natl Acad Sci U S A 2006; 103:13310-4. [PMID: 16938857 PMCID: PMC1557386 DOI: 10.1073/pnas.0606116103] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigate the phase behavior of surface-functionalized silica colloids at both the molecular and macroscopic levels. This investigation allows us to relate collective properties such as aggregation, gelation, and aging directly to molecular interfacial behavior. By using surface-specific vibrational spectroscopy, we reveal dramatic changes in the conformation of alkyl chains terminating submicrometer silica particles. In fluid suspension at high temperatures, the interfacial molecules are in a liquid-like state of conformational disorder. As the temperature is lowered, the onset of gelation is identified by macroscopic phenomena, including changes in turbidity, heat release, and diverging viscosity. At the molecular level, the onset of this transition coincides with straightening of the carbon-carbon backbones of the interfacial molecules. In later stages, their intermolecular crystalline packing improves. It is the increased density of this ordered boundary layer that increases the van der Waals attraction between particles, causing the colloidal gas to aggregate. The approach presented here can provide insights into phase transitions that occur through surface modifications in a variety of colloidal systems.
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Affiliation(s)
- Sylvie Roke
- Max Planck Institute for Metals Research, Heisenbergstrasse 3, 70569 Stuttgart, Germany.
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37
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Mohraz A, Solomon MJ. Gelation and internal dynamics of colloidal rod aggregates. J Colloid Interface Sci 2006; 300:155-62. [PMID: 16631779 DOI: 10.1016/j.jcis.2006.03.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2005] [Revised: 02/27/2006] [Accepted: 03/19/2006] [Indexed: 11/26/2022]
Abstract
The internal dynamics of fractal cluster gels of colloidal boehmite rods with aspect ratios r = 3.9, 8.6, and 30.1, and colloidal polystyrene spheres (r = 1) are reported. Increasing r decreases the minimum colloid volume fraction for gelation. The behavior of the dynamic structure factor of rod gels is consistent with the internal dynamics of a constrained Brownian fractal object. Colloidal boehmite gels display an abrupt transition from floppy to brittle dynamics at phi approximately 10(-4). Moreover, the fractal cluster size of rod gels is not the determinant of the relaxation time of density fluctuations as it is in spherical particle gels. Instead, the relative behavior of the magnitude and time scale of the constrained fluctuations suggests that the fractal rod network is viscously coupled only on local, rather than cluster, scales. We hypothesize that noncentral forces between the anisometric particles are responsible for this anomalous behavior.
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Affiliation(s)
- Ali Mohraz
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136, USA.
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38
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Dinsmore AD, Prasad V, Wong IY, Weitz DA. Microscopic structure and elasticity of weakly aggregated colloidal gels. PHYSICAL REVIEW LETTERS 2006; 96:185502. [PMID: 16712371 DOI: 10.1103/physrevlett.96.185502] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Indexed: 05/09/2023]
Abstract
We directly probe the microscopic structure, connectivity, and elasticity of colloidal gels using confocal microscopy. We show that the gel is a random network of one-dimensional chains of particles. By measuring thermal fluctuations, we determine the effective spring constant between pairs of particles as a function of separation; this is in agreement with the theory for fractal chains. Long-range attractions between particles lead to freely rotating bonds, and the gel is stabilized by multiple connections among the chains. By contrast, short-range attractions lead to bonds that resist bending, with dramatically suppressed formation of loops of particles.
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Affiliation(s)
- A D Dinsmore
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Bastea S. Aggregation kinetics in a model colloidal suspension. PHYSICAL REVIEW LETTERS 2006; 96:028305. [PMID: 16486658 DOI: 10.1103/physrevlett.96.028305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Indexed: 05/06/2023]
Abstract
We present molecular dynamics simulations of aggregation kinetics in a colloidal suspension modeled as a highly asymmetric binary mixture. Starting from a configuration with largely uncorrelated colloidal particles the system relaxes by coagulation-fragmentation dynamics to a structured state of low-dimensionality clusters with an exponential size distribution. The results show that short-range repulsive interactions alone can give rise to so-called cluster phases. For the present model and probably other, more common colloids, the observed clusters appear to be equilibrium phase fluctuations induced by the entropic intercolloidal attractions.
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Affiliation(s)
- Sorin Bastea
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
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Kaneko T. The effects of the physical cluster formation on pair-correlation functions for an ionic fluid. J Chem Phys 2005; 123:134509. [PMID: 16223316 DOI: 10.1063/1.2013258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A system of two integral equations, which is equivalent to the Ornstein-Zernike equation, results in two kinds of correlation functions which describe the apparent effects of the physical cluster formation on pair-correlation functions. Each pair-correlation function is equivalent to the sum of the two kinds of correlation functions, and the development of physical clusters, which are formed in an ionic fluid owing to the attractive Coulomb force between positive and negative charged particles, allows the dependence of the sum on the distance r between particular pair particles to develop the deviation from the behavior characterized as r-1. Then, their development makes the dependence of the sum on r have a tendency to approach the behavior characterized as r-3/2, and the two kinds of correlation functions aid in describing fractal structures of nonuniform particle distributions in ionic fluids.
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Affiliation(s)
- Tetsuo Kaneko
- Kurakenchikuzokeisha Company, Ltd., Shimo 1-27-22, Kita-ku, Tokyo 115-0042, Japan.
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42
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Harris NC, Kiang CH. Disorder in DNA-linked gold nanoparticle assemblies. PHYSICAL REVIEW LETTERS 2005; 95:046101. [PMID: 16090823 PMCID: PMC2682730 DOI: 10.1103/physrevlett.95.046101] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Indexed: 05/03/2023]
Abstract
We report experimental observations on the effect of disorder on the phase behavior of DNA-linked nanoparticle assemblies. Variation in DNA linker lengths results in different melting temperatures of the DNA-linked nanoparticle assemblies. We observed an unusual trend of a nonmonotonic "zigzag" pattern in the melting temperature as a function of DNA linker length. Linker DNA resulting in unequal DNA duplex lengths introduces disorder and lowers the melting temperature of the nanoparticle system. Comparison with free DNA thermodynamics shows that such an anomalous zigzag pattern does not exist for free DNA duplex melting, which suggests that the disorder introduced by unequal DNA duplex lengths results in this unusual collective behavior of DNA-linked nanoparticle assemblies.
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Manley S, Davidovitch B, Davies NR, Cipelletti L, Bailey AE, Christianson RJ, Gasser U, Prasad V, Segre PN, Doherty MP, Sankaran S, Jankovsky AL, Shiley B, Bowen J, Eggers J, Kurta C, Lorik T, Weitz DA. Time-dependent strength of colloidal gels. PHYSICAL REVIEW LETTERS 2005; 95:048302. [PMID: 16090846 DOI: 10.1103/physrevlett.95.048302] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Indexed: 05/03/2023]
Abstract
Colloidal silica gels are shown to stiffen with time, as demonstrated by both dynamic light scattering and bulk rheological measurements. Their elastic moduli increase as a power law with time, independent of particle volume fraction; however, static light scattering indicates that there are no large-scale structural changes. We propose that increases in local elasticity arising from bonding between neighboring colloidal particles can account for the strengthening of the network, while preserving network structure.
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Affiliation(s)
- S Manley
- Department of Physics & DEAS, Harvard University, Cambridge, Massachusetts 02138, USA
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Manley S, Skotheim JM, Mahadevan L, Weitz DA. Gravitational collapse of colloidal gels. PHYSICAL REVIEW LETTERS 2005; 94:218302. [PMID: 16090356 DOI: 10.1103/physrevlett.94.218302] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Indexed: 05/03/2023]
Abstract
We present a unified framework for understanding the compaction of colloidal gels under their own weight. The dynamics of the collapse are determined by the value of the gravitational stress sigma(g), as compared to the yield stress sigma(Y) of the network. For sigma(g)<sigma(Y), gels collapse poroelastically, and their rate of compression decays exponentially in time. For sigma(g)>sigma(Y), the network eventually yields, leading to rapid settling. In both cases, the rate of collapse is backflow limited, while its overall magnitude is determined by a balance between gravitational stress and network elastic stress.
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Affiliation(s)
- S Manley
- Department of Physics and DEAS, Harvard University, Cambridge, Massachusetts 02138, USA
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Sandkühler P, Lattuada M, Wu H, Sefcik J, Morbidelli M. Further insights into the universality of colloidal aggregation. Adv Colloid Interface Sci 2005; 113:65-83. [PMID: 15935139 DOI: 10.1016/j.cis.2004.12.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 12/08/2004] [Indexed: 10/25/2022]
Abstract
Dynamic light scattering (DLS) performed at various scattering wave vectors provides detailed information about the aggregation kinetics and the cluster mass distribution (CMD) in colloidal dispersions. Detailed modeling of the aggregation kinetics with population balance equations requires a quantitative connection between the CMD and measurable quantities such as the angle dependent hydrodynamic radii obtained by DLS. For this purpose we evaluate and compare various models for the structure factor of fractal aggregates. Additionally, we introduce a simple scattering model that accounts for the contribution of internal cluster dynamics of fractal clusters to the first cumulant of the dynamic structure factor. We show that this contribution allows to quantitatively describe previously measured experimental data on the scattering wave vector dependence of the hydrodynamic radius in diffusion limited cluster-cluster aggregation (DLCA), which was shown to exhibit some kind of universality behavior (master curve). Using the same scattering model, we analyze a similar set of experimental data but in reaction limited cluster-cluster aggregation (RLCA). We find that in this case the crossover from RLCA to DLCA and gravitational settling both have a significant influence on the CMD and consequently on the scattering wave vector dependent DLS data. Only when accounting for both these effects they temporarily compensate each other and a satisfactory representation of the aggregation master curve is possible for the RLCA data at longer times. Indeed, we find that either crossover from RLCA to DLCA or gravitational settling, when present individually, causes the loss of a master curve for aggregation.
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Affiliation(s)
- Peter Sandkühler
- Swiss Federal Institute of Technology Zurich, Institut für Chemie- und Bioingenieurwissenschaften ETH-Hönggerberg/HCI, CH-8093 Zurich, Switzerland
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46
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Castellanos A, Valverde JM, Quintanilla MAS. Physics of compaction of fine cohesive particles. PHYSICAL REVIEW LETTERS 2005; 94:075501. [PMID: 15783824 DOI: 10.1103/physrevlett.94.075501] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Indexed: 05/24/2023]
Abstract
Fluidized fractal clusters of fine particles display critical-like dynamics at the jamming transition, characterized by a power law relating consolidation stress with volume fraction increment [sigma--(c) proportional, variant(Deltaphi)(beta)]. At a critical stress clusters are disrupted and there is a crossover to a logarithmic law (Deltaphi = nu logsigma--(c)) resembling the phenomenology of soils. We measure lambda identical with- partial differentialDelta(1/phi)/ partial log(sigma--(c) proportional, variant Bo(0.2)(g), where Bo(g) is the ratio of interparticle attractive force (in the fluidlike regime) to particle weight. This law suggests that compaction is ruled by the internal packing structure of the jammed clusters at nearly zero consolidation.
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Affiliation(s)
- A Castellanos
- Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, Avenida Reina Mercedes s/n, 41012 Sevilla, Spain
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