1
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Feng K, Shen W, Chen L, Gong J, Palberg T, Qu J, Niu R. Weak Ion-Exchange Based Magnetic Swarm for Targeted Drug Delivery and Chemotherapy. Small 2023:e2306798. [PMID: 38059804 DOI: 10.1002/smll.202306798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/06/2023] [Indexed: 12/08/2023]
Abstract
Swimming microrobots that are actuated by multiple stimuli/fields display various intriguing collective behaviors, ranging from phase separation to clustering and giant number fluctuation; however, it is still chanllenging to achieve multiple responses and functionalities within one colloidal system to emulate high environmental adaptability and improved tasking capability of natural swarms. In this work, a weak ion-exchange based swarm is presented that can self-organize and reconfigure by chemical, light, and magnetic fields, showing living crystal, amorphous glass, liquid, chain, and wheel-like structures. By changing the frequency and strength of the rotating magnetic field, various well-controlled and fast transformations are obtained. Experiments show the high adaptability and functionality of the microrobot swarm in delivering drugs in confined spaces, such as narrow channels with turns or obstacles. The drug-carrying swarm exhibits excellent chemtherapy for Hela and CT26 cells due to the pH-enhanced drug release and locomotion. This reconfigurable microswarm provides a new platform for biomedical and environmental applications.
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Affiliation(s)
- Kai Feng
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Semiconductor Chemistry Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wenqi Shen
- Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
| | - Ling Chen
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Semiconductor Chemistry Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jiang Gong
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Semiconductor Chemistry Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Thomas Palberg
- Institut für physics, Johannes Gutenberg-Universtät Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Jinping Qu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Semiconductor Chemistry Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Ran Niu
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Semiconductor Chemistry Center, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
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2
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Vogel P, Palberg T. Electrokinetic effects of ambient and excess carbonization of dielectric surfaces in aqueous environments. J Colloid Interface Sci 2023; 656:280-288. [PMID: 37995398 DOI: 10.1016/j.jcis.2023.10.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 11/25/2023]
Abstract
The charge state of surfaces in contact with aqueous electrolytes is crucial for the performance and stability of dielectric surfaces in general and lyophobic colloids in particular. Thus far the role of adsorbed molecular CO2 remained largely unexplored. The aim of the present investigation is to study the de-charging and re-charging for two model surfaces upon addition of CO2 and/or 1:1 electrolytes (NaCl, HCl) under precisely controlled boundary conditions up to millimolar concentrations of additives. Starting from the salt- and CO2-free state, the ζ-potential magnitudes drop linearly with the logarithm of the CO2-concentrations over several orders of magnitude in CO2-concentrations. Hydrophobic Polystyrene nearly fully discharges, hydrophilic SiO2 reveals a 60% charge reduction. From the surface specific effects of instead adding NaCl or HCl, we discriminate and parameterize empirically the relative contribution of three individual mechanisms for decreasing the ζ-potential magnitudes (screening, pH-driven charge regulation, dielectric charge regulation) combining during CO2-addition. Moreover, depending on the achieved CO2-induced de-charging, the behavior upon subsequent addition of NaCl and HCl switches between two limiting cases. Screening dominates for surfaces in the native state without CO2, but a significant re-charging is observed for surfaces conditioned under excess CO2-concentrations.
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Affiliation(s)
- Peter Vogel
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany.
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
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3
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Möller N, Hecht L, Niu R, Liebchen B, Palberg T. Writing Into Water. Small 2023:e2303741. [PMID: 37603386 DOI: 10.1002/smll.202303741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/15/2023] [Indexed: 08/22/2023]
Abstract
Writing is an ancient communication technique dating back at least 30 000 years. While even sophisticated contemporary writing techniques hinge on solid surfaces for engraving or the deposition of ink, writing within a liquid medium requires a fundamentally different approach. The study here demonstrates the writing of lines, letters, and complex patterns in water by assembling lines of colloidal particles. Unlike established techniques for underwater writing on solid substrates, these lines are fully reconfigurable and do not require any fixation onto the substrate. Exploiting gravity, an ion-exchange bead (pen) is rolled across a layer of sedimented colloidal particles (ink). The pen evokes a hydrodynamic flow collecting ink-particles into a durable, high-contrast line along its trajectory. Deliberate substrate-tilting sequences facilitate pen-steering and thus drawing and writing. The experiments are complemented with a minimal model that quantitatively predicts the observed parameter dependence for writing in fluids and highlights the generic character of writing by line-assembly. Overall, the approach opens a versatile route for writing, drawing, and patterning fluids-even at the micro-scale.
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Affiliation(s)
- Nadir Möller
- Institut für Physik, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
| | - Lukas Hecht
- Institute for Condensed Matter Physics, Department of Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Ran Niu
- Institut für Physik, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
- Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, 430074, China
| | - Benno Liebchen
- Institute for Condensed Matter Physics, Department of Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
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4
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Tanuku VMSG, Vogel P, Palberg T, Buttinoni I. Island hopping of active colloids. Soft Matter 2023. [PMID: 37432377 DOI: 10.1039/d3sm00446e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Individual self-propelled colloidal particles, like active Brownian particles (ABP) or run-and-tumble (RT) swimmers, exhibit characteristic and well-known motion patterns. However, their interaction with obstacles remains an open and important problem. We here investigate the two-dimensional motion of silica-gold Janus particles (JP) suspended in a bath of smaller silica passive particles. Actuated by AC electric fields, the JP cruise through passive colloids organized in 'islands' due to attractive electrohydrodynamic (EHD) flows. A typical island contains dozens of particles. The JP travels straight in obstacle-free regions and reorients abruptly upon collision with an island. As an underlying mechanism, we propose that the scattering events are caused by the interplay of EHD flows, self-propulsion and local torques. The combination of directed motion and sudden reorientations leads to active trajectories resembling the RT behavior of biological microswimmers.
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Affiliation(s)
| | - Peter Vogel
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany.
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany.
| | - Ivo Buttinoni
- Institute for Experimental Physics of Condensed Matter, Heinrich-Heine University, 40225 Düsseldorf, Germany
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5
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Lorenz N, Wittenberg C, Palberg T. Porous crystals in charged sphere suspensions by aggregate-driven phase separation. Soft Matter 2023. [PMID: 37367202 DOI: 10.1039/d3sm00660c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The kinetics of phase transition processes often governs the resulting material microstructure. Using optical microscopy, we here investigate the formation and stabilization of a porous crystalline microstructure forming in low-salt suspensions of charged colloidal spheres containing aggregates comprising some 5-10 of these colloids. We observe the transformation of an initially crystalline colloidal solid with homogeneously incorporated aggregates to individual, compositionally refined crystallites of perforated morphology coexisting with an aggregate-enriched fluid phase filling the holes and separating individual crystallites. A preliminary kinetic characterization suggests that the involved processes follow power laws. We show that this route to porous materials is neither restricted to nominally single component systems nor to a particular microstructure to start from. However, it necessitates an early rapid solidification stage during which the aggregates become trapped in the bulk of the host-crystals. The thermodynamic stability of the reconstructed crystalline scaffold against melting under increased salinity was found comparable to that of pure phase crystallites grown very slowly from a melt. Future implications of this novel route to porous colloidal crystals are discussed.
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Affiliation(s)
- Nina Lorenz
- Institute of Physics, Johannes Gutenberg Universität Mainz, Germany.
| | | | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg Universität Mainz, Germany.
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6
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Lorenz N, Gupta I, Palberg T. Microstructural diversity, nucleation paths, and phase behavior in binary mixtures of charged colloidal spheres. J Chem Phys 2023; 158:114902. [PMID: 36948792 DOI: 10.1063/5.0140949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023] Open
Abstract
We study low-salt, binary aqueous suspensions of charged colloidal spheres of size ratio Γ = 0.57, number densities below the eutectic number density nE, and number fractions of p = 1.00-0.40. The typical phase obtained by solidification from a homogeneous shear-melt is a substitutional alloy with a body centered cubic structure. In strictly gas-tight vials, the polycrystalline solid is stable against melting and further phase transformation for extended times. For comparison, we also prepare the same samples by slow, mechanically undisturbed deionization in commercial slit cells. These cells feature a complex but well reproducible sequence of global and local gradients in salt concentration, number density, and composition as induced by successive deionization, phoretic transport, and differential settling of the components, respectively. Moreover, they provide an extended bottom surface suitable for heterogeneous nucleation of the β-phase. We give a detailed qualitative characterization of the crystallization processes using imaging and optical microscopy. By contrast to the bulk samples, the initial alloy formation is not volume-filling, and we now observe also α- and β-phases with low solubility of the odd component. In addition to the initial homogeneous nucleation route, the interplay of gradients opens various further crystallization and transformation pathways leading to a great diversity of microstructures. Upon a subsequent increase in salt concentration, the crystals melt again. Wall-based, pebble-shaped β-phase crystals and facetted α-crystals melt last. Our observations suggest that the substitutional alloys formed in bulk experiments by homogeneous nucleation and subsequent growth are mechanically stable in the absence of solid-fluid interfaces but thermodynamically metastable.
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Affiliation(s)
- Nina Lorenz
- Institute of Physics, Johannes Gutenberg University, 55122 Mainz, Germany
| | - Ishan Gupta
- Graz University of Technology, Institute of Applied Mechanics, Graz, Austria
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55122 Mainz, Germany
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7
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Vogel P, Möller N, Qaisrani MN, Bista P, Weber SAL, Butt HJ, Liebchen B, Sulpizi M, Palberg T. Charging of Dielectric Surfaces in Contact with Aqueous Electrolytes─the Influence of CO 2. J Am Chem Soc 2022; 144:21080-21087. [DOI: 10.1021/jacs.2c06793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Peter Vogel
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
| | - Nadir Möller
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
| | | | - Pravash Bista
- Max Planck Institute for Polymer Research, 55128Mainz, Germany
| | | | | | - Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289Darmstadt, Germany
| | - Marialore Sulpizi
- Department of Physics, Ruhr Universität Bochum, 44780Bochum, Germany
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
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8
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Schwarz J, Leiderer P, Palberg T. Salt-concentration-dependent nucleation rates in low-metastability colloidal charged sphere melts containing small amounts of doublets. Phys Rev E 2021; 104:064607. [PMID: 35030906 DOI: 10.1103/physreve.104.064607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
We determined bulk crystal nucleation rates in aqueous suspensions of charged spheres at low metastability. Experiments were performed in dependence on electrolyte concentration and for two different particle number densities. The time-dependent nucleation rate shows a pronounced initial peak, while postsolidification crystal size distributions are skewed towards larger crystallite sizes. At each concentration, the nucleation rate density initially drops exponentially with increasing salt concentration. The full data set, however, shows an unexpected scaling of the nucleation rate densities with metastability times the number density of particles. Parameterization of our results in terms of classical nucleation theory reveals unusually low interfacial free energies of the nucleus surfaces and nucleation barriers well below the thermal energy. We tentatively attribute our observations to the presence of doublets introduced by the employed conditioning technique. We discuss the conditions under which such small seeds may induce nucleation.
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Affiliation(s)
- J Schwarz
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
| | - P Leiderer
- Fachbereicht Physik, University of Konstanz, 78457 Konstanz, Germany
| | - T Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
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9
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Möller N, Liebchen B, Palberg T. Shaping the gradients driving phoretic micro-swimmers: influence of swimming speed, budget of carbonic acid and environment. Eur Phys J E Soft Matter 2021; 44:41. [PMID: 33759011 PMCID: PMC7987694 DOI: 10.1140/epje/s10189-021-00026-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/22/2021] [Indexed: 05/07/2023]
Abstract
pH gradient-driven modular micro-swimmers are investigated as a model for a large variety of quasi-two-dimensional chemi-phoretic self-propelled entities. Using three-channel micro-photometry, we obtain a precise large field mapping of pH at a spatial resolution of a few microns and a pH resolution of [Formula: see text] units for swimmers of different velocities propelling on two differently charged substrates. We model our results in terms of solutions of the three-dimensional advection-diffusion equation for a 1:1 electrolyte, i.e. carbonic acid, which is produced by ion exchange and consumed by equilibration with dissolved [Formula: see text]. We demonstrate the dependence of gradient shape and steepness on swimmer speed, diffusivity of chemicals, as well as the fuel budget. Moreover, we experimentally observe a subtle, but significant feedback of the swimmer's immediate environment in terms of a substrate charge-mediated solvent convection. We discuss our findings in view of different recent results from other micro-fluidic or active matter investigations. We anticipate that they are relevant for quantitative modelling and targeted applications of diffusio-phoretic flows in general and artificial micro-swimmers in particular.
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Affiliation(s)
- Nadir Möller
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
- Max Planck Graduade Center, Institute of Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
| | - Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Thomas Palberg
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
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10
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Sachs J, Kottapalli SN, Fischer P, Botin D, Palberg T. Characterization of active matter in dense suspensions with heterodyne laser Doppler velocimetry. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04693-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractWe present a novel approach for characterizing the properties and performance of active matter in dilute suspension as well as in crowded environments. We use Super-Heterodyne Laser-Doppler-Velocimetry (SH-LDV) to study large ensembles of catalytically active Janus particles moving under UV illumination. SH-LDV facilitates a model-free determination of the swimming speed and direction, with excellent ensemble averaging. In addition, we obtain information on the distribution of the catalytic activity. Moreover, SH-LDV operates away from walls and permits a facile correction for multiple scattering contributions. It thus allows for studies of concentrated suspensions of swimmers or of systems where swimmers propel actively in an environment crowded by passive particles. We demonstrate the versatility and the scope of the method with a few selected examples. We anticipate that SH-LDV complements established methods and paves the way for systematic measurements at previously inaccessible boundary conditions.
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11
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Botin D, Carrique F, Ruiz-Reina E, Palberg T. Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions. J Chem Phys 2020; 152:244902. [PMID: 32610949 DOI: 10.1063/5.0010692] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO2. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms.
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Affiliation(s)
- Denis Botin
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Felix Carrique
- Institute Carlos I for Theoretical and Computational Physics (iC1), Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - Emilio Ruiz-Reina
- Institute Carlos I for Theoretical and Computational Physics (iC1), Departamento de Física Aplicada II, Escuela de Ingenierías Industriales, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
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12
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Abstract
We present a framework to quantitatively predict the linear and rotational directed motion of synthetic modular microswimmers. To this end, we study binary dimers and characterize their approach motion as effective interactions within a minimal model. We apply this framework to the assembly of small aggregates composed of a cationic ion-exchange particle with up to five passive particles or anionic ion-exchange particles at dilute conditions. Particles sediment and move close to a substrate, above which the ion-exchange particles generate flow. This flow mediates long-range attractions leading to a slow collapse during which long-lived clusters of a few particles assemble. The effective interactions between unlike particles break Newton's third law. Depending on their symmetry, assemblies thus can become linear or circle swimmers, or remain inert (no directed motion).
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Affiliation(s)
- Ran Niu
- Institut für Physik , Johannes Gutenberg Universität Mainz , Staudingerweg 7-9 , 55128 Mainz , Germany
| | - Andreas Fischer
- Institut für Physik , Johannes Gutenberg Universität Mainz , Staudingerweg 7-9 , 55128 Mainz , Germany
| | - Thomas Palberg
- Institut für Physik , Johannes Gutenberg Universität Mainz , Staudingerweg 7-9 , 55128 Mainz , Germany
| | - Thomas Speck
- Institut für Physik , Johannes Gutenberg Universität Mainz , Staudingerweg 7-9 , 55128 Mainz , Germany
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13
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Botin D, Wenzl J, Niu R, Palberg T. Colloidal electro-phoresis in the presence of symmetric and asymmetric electro-osmotic flow. Soft Matter 2018; 14:8191-8204. [PMID: 30259053 DOI: 10.1039/c8sm00934a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We characterize the electro-phoretic motion of charged sphere suspensions in the presence of substantial electro-osmotic flow using a recently introduced small angle super-heterodyne dynamic light scattering instrument (ISASH-LDV). Operation in integral mode gives access to the particle velocity distribution over the complete cell cross-section. Obtained Doppler spectra are evaluated for electro-phoretic mobility, wall electro-osmotic mobility and particle diffusion coefficient. Simultaneous measurements of differing electro-osmotic mobilities leading to asymmetric solvent flow are demonstrated in a custom made electro-kinetic cell fitting standard microscopy slides as exchangeable sidewalls. The scope and range of our approach are discussed demonstrating the possibility of an internal calibration standard and using the simultaneously measured electro-kinetic mobilities in the interpretation of a microfluidic pumping experiment involving an inhomogeneous electric field and a complex solvent flow pattern.
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Affiliation(s)
- Denis Botin
- Institute of Physics, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Jennifer Wenzl
- Institute of Physics, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Ran Niu
- Institute of Physics, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, D-55099 Mainz, Germany.
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14
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Abstract
The field of active matter in general and microswimming in particular has experienced a rapid and ongoing expansion over the last decade. A particular interesting aspect is provided by artificial autonomous microswimmers constructed from individual active and inactive functional components into self-propelling complexes. Such modular microswimmers may exhibit directed motion not seen for each individual component. In this review, we focus on the establishment and recent developments in the modular approach to microswimming. We introduce the bound and dynamic prototypes, show mechanisms and types of modular swimming and discuss approaches to control the direction and speed of modular microswimmers. We conclude by highlighting some challenges faced by researchers as well as promising directions for future research in the realm of modular swimming.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes Gutenberg-Universtät Mainz, Staudingerweg 7, 55128 Mainz, Germany.
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15
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Niu R, Palberg T. Correction: Seedless assembly of colloidal crystals by inverted micro-fluidic pumping. Soft Matter 2018; 14:7542. [PMID: 30167615 DOI: 10.1039/c8sm90158a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Correction for 'Seedless assembly of colloidal crystals by inverted micro-fluidic pumping' by Ran Niu et al., Soft Matter, 2018, 14, 3435-3442.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes-Gutenberg Universität, Staudingerweg 7, 55128, Mainz, Germany.
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16
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Schaertl N, Botin D, Palberg T, Bartsch E. Formation of Laves phases in buoyancy matched hard sphere suspensions. Soft Matter 2018; 14:5130-5139. [PMID: 29881859 DOI: 10.1039/c7sm02348k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Colloidal Laves phases (LPs) are promising precursors for photonic materials. Laves phases have not yet been observed to form in experiments on colloidal suspensions of hard spheres (HS), even though they have been reported in computer simulations. LP formation so far has been achieved only for binary mixtures of colloidal charged spheres or ligand-stabilized nano-particles after drying. Using static light scattering, we monitored LP formation and annealing in a binary mixture of buoyant hard sphere approximants (size ratio Γ = 0.77, number or molar fraction of small spheres xS = 0.76) for volume fractions in the fluid-crystal coexistence regions. All samples spontaneously formed MgZn2 type LPs on the time scale of weeks to months via bulk nucleation and growth. Irrespective of the initial suspension volume fractions, the LP volume fraction at coexistence is ΦCOEX = 0.59 which is significantly below the close packing limit ΦMAX = 0.615 and remarkably close to the expectation from simulation. At low volume fractions, crystals anneal to high quality during coarsening which is in line with recent theoretical expectations for the thermodynamic stability of different LP types. At large volume fractions, however, the diffractograms evolve towards a more MgCu2-like appearance which we attribute to the formation of randomly stacked LPs. Such structures are not known from atomic systems.
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Affiliation(s)
- N Schaertl
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany.
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17
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Abstract
We propose a simple seedless approach to assemble millimeter sized monolayer single colloidal crystals with desired orientations at predetermined locations on an unstructured charged substrate. This approach utilizes the millimeter-ranged fluid flow on the bottom glass substrate induced by an ion exchange resin (IEX) fixed on top of the closed sample cell. The fluid flow increases with decreasing height of the sample cell and increasing radius R of the IEX. For a single inverted pump, millimeter sized monolayer single crystals of hexagonal close packing can be obtained. For two closely spaced (D ∼ 4R) pumps, the formed crystals have a predefined orientation along the line connecting the two IEX. By patterning IEX into different structures, colloidal crystals of different complex patterns form. The present method paves a convenient way for fabricating high quality monolayer colloidal crystals for a variety of applications.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes-Gutenberg Universität, Staudingerweg 7, 55128, Mainz, Germany.
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Niu R, Oğuz EC, Müller H, Reinmüller A, Botin D, Löwen H, Palberg T. Controlled assembly of single colloidal crystals using electro-osmotic micro-pumps. Phys Chem Chem Phys 2018; 19:3104-3114. [PMID: 28079208 DOI: 10.1039/c6cp07231c] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We assemble charged colloidal spheres at deliberately chosen locations on a charged unstructured glass substrate utilizing ion exchange based electro-osmotic micro-pumps. Using microscopy, a simple scaling theory and Brownian dynamics computer simulations, we systematically explore the control parameters of crystal assembly and the mechanisms through which they depend on the experimental boundary conditions. We demonstrate that crystal quality depends crucially on the assembly distance of the colloids. This is understood as resulting from the competition between inward transport by the electro-osmotic pump flow and the electro-phoretic outward motion of the colloids. Optimized conditions include substrates of low and colloids of large electro-kinetic mobility. Then a sorting of colloids by size is observed in binary mixtures with larger particles assembling closer to the ion exchanger beads. Moreover, mono-sized colloids form defect free single domain crystals which grow outside a colloid-free void with facetted inner crystal boundaries centered on the ion exchange particle. This works remarkably well, even with irregularly formed ion exchange resin splinters.
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Affiliation(s)
- Ran Niu
- Institute of Physics, exp. Soft Matter Group KOMET336, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Erdal C Oğuz
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine-University, D-40225 Düsseldorf, Germany
| | - Hannah Müller
- Institute of Physics, exp. Soft Matter Group KOMET336, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Alexander Reinmüller
- Institute of Physics, exp. Soft Matter Group KOMET336, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Denis Botin
- Institute of Physics, exp. Soft Matter Group KOMET336, Johannes Gutenberg University, D-55099 Mainz, Germany.
| | - Hartmut Löwen
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine-University, D-40225 Düsseldorf, Germany
| | - Thomas Palberg
- Institute of Physics, exp. Soft Matter Group KOMET336, Johannes Gutenberg University, D-55099 Mainz, Germany.
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19
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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20
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Abstract
The emergence of structure through aggregation is a fascinating topic and of both fundamental and practical interest. Here we demonstrate that self-generated solvent flow can be used to generate long-range attractions on the colloidal scale, with subpiconewton forces extending into the millimeter range. We observe a rich dynamic behavior with the formation and fusion of small clusters resembling molecules. The dynamics of this assembly is governed by an effective conservative energy that for large separations r decays as 1/r. Breaking the flow symmetry, these clusters can be made active.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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21
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Botin D, Mapa LM, Schweinfurth H, Sieber B, Wittenberg C, Palberg T. An empirical correction for moderate multiple scattering in super-heterodyne light scattering. J Chem Phys 2017; 146:204904. [PMID: 28571383 PMCID: PMC5444921 DOI: 10.1063/1.4983688] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/04/2017] [Indexed: 11/14/2022] Open
Abstract
Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.
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Affiliation(s)
- Denis Botin
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | | | | | - Bastian Sieber
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | | | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
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22
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Abstract
We report an experimental study on ion-exchange-based modular microswimmers in low-salt water. Cationic ion-exchange particles and passive cargo particles assemble into self-propelling complexes, showing self-propulsion at speeds of several micrometers per second over extended distances and times. We quantify the assembly and speed of the complexes for different combinations of ion-exchange particles and cargo particles, substrate types, salt types and concentrations, and cell geometries. Irrespective of the experimental boundary conditions, we observe a regular development of the assembly shape with increasing number of cargo. Moreover, the swimming speed increases stepwise upon increasing the number of cargo and then saturates at a maximum speed, indicating the active role of cargo in modular swimming. We propose a geometric model of self-assembly to describe the experimental observations in a qualitative way. Our study also provides some constraints for future theoretical modeling and simulation.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes Gutenberg-Universtät Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Denis Botin
- Institut für Physik, Johannes Gutenberg-Universtät Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Julian Weber
- Institut für Physik, Johannes Gutenberg-Universtät Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Alexander Reinmüller
- Institut für Physik, Johannes Gutenberg-Universtät Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg-Universtät Mainz , Staudingerweg 7, 55128 Mainz, Germany
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23
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Kozina A, Sagawe D, Díaz-Leyva P, Bartsch E, Palberg T. Correction: Polymer-enforced crystallization of a eutectic binary hard sphere mixture. Soft Matter 2017; 13:2410. [PMID: 28267177 DOI: 10.1039/c7sm90034a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Correction for 'Polymer-enforced crystallization of a eutectic binary hard sphere mixture' by Anna Kozina et al., Soft Matter, 2012, 8, 627-630.
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Affiliation(s)
- Anna Kozina
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany
| | - Dominik Sagawe
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany
| | - Pedro Díaz-Leyva
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany and Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany
| | - Eckhard Bartsch
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany and Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, D-79104, Freiburg, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55128, Mainz, Germany
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24
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Niu R, Kreissl P, Brown AT, Rempfer G, Botin D, Holm C, Palberg T, de Graaf J. Microfluidic pumping by micromolar salt concentrations. Soft Matter 2017; 13:1505-1518. [PMID: 28127614 DOI: 10.1039/c6sm02240e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
An ion-exchange-resin-based microfluidic pump is introduced that utilizes trace amounts of ions to generate fluid flows. We show experimentally that our pump operates in almost deionized water for periods exceeding 24 h and induces fluid flows of μm s-1 over hundreds of μm. This flow displays a far-field, power-law decay which is characteristic of two-dimensional (2D) flow when the system is strongly confined and of three-dimensional (3D) flow when it is not. Using theory and numerical calculations we demonstrate that our observations are consistent with electroosmotic pumping driven by μmol L-1 ion concentrations in the sample cell that serve as 'fuel' to the pump. Our study thus reveals that trace amounts of charge carriers can produce surprisingly strong fluid flows; an insight that should benefit the design of a new class of microfluidic pumps that operate at very low fuel concentrations.
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Affiliation(s)
- Ran Niu
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - Patrick Kreissl
- Institute for Computational Physics, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
| | - Aidan T Brown
- SUPA, School of Physics and Astronomy, University of Edinburgh, JCMB Kings Buildings, Edinburgh EH9 3FD, UK.
| | - Georg Rempfer
- Institute for Computational Physics, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
| | - Denis Botin
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - Christian Holm
- Institute for Computational Physics, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - Joost de Graaf
- SUPA, School of Physics and Astronomy, University of Edinburgh, JCMB Kings Buildings, Edinburgh EH9 3FD, UK.
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25
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Trefalt G, Palberg T, Borkovec M. Forces between colloidal particles in aqueous solutions containing monovalent and multivalent ions. Curr Opin Colloid Interface Sci 2017. [DOI: 10.1016/j.cocis.2016.09.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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26
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Herlach DM, Palberg T, Klassen I, Klein S, Kobold R. Overview: Experimental studies of crystal nucleation: Metals and colloids. J Chem Phys 2016; 145:211703. [DOI: 10.1063/1.4963684] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dieter M. Herlach
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany
| | - Ina Klassen
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
- Projektträger Jülich, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Stefan Klein
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Raphael Kobold
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
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27
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Palberg T, Wette P, Herlach DM. Equilibrium fluid-crystal interfacial free energy of bcc-crystallizing aqueous suspensions of polydisperse charged spheres. Phys Rev E 2016; 93:022601. [PMID: 26986371 DOI: 10.1103/physreve.93.022601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Indexed: 06/05/2023]
Abstract
The interfacial free energy is a central quantity in crystallization from the metastable melt. In suspensions of charged colloidal spheres, nucleation and growth kinetics can be accurately measured from optical experiments. In previous work, from these data effective nonequilibrium values for the interfacial free energy between the emerging bcc nuclei and the adjacent melt in dependence on the chemical potential difference between melt phase and crystal phase were derived using classical nucleation theory (CNT). A strictly linear increase of the interfacial free energy was observed as a function of increased metastability. Here, we further analyze these data for five aqueous suspensions of charged spheres and one binary mixture. We utilize a simple extrapolation scheme and interpret our findings in view of Turnbull's empirical rule. This enables us to present the first systematic experimental estimates for a reduced interfacial free energy, σ(0,bcc), between the bcc-crystal phase and the coexisting equilibrium fluid. Values obtained for σ(0,bcc) are on the order of a few k(B)T. Their values are not correlated to any of the electrostatic interaction parameters but rather show a systematic decrease with increasing size polydispersity and a lower value for the mixture as compared to the pure components. At the same time, σ(0) also shows an approximately linear correlation to the entropy of freezing. The equilibrium interfacial free energy of strictly monodisperse charged spheres may therefore be still greater.
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Affiliation(s)
- Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany
| | - Patrick Wette
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51147 Köln, Germany
- Space Administration, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 53227 Bonn, Germany
| | - Dieter M Herlach
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51147 Köln, Germany
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28
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Beyer R, Franke M, Schöpe HJ, Bartsch E, Palberg T. From nuclei to micro-structure in colloidal crystallization: Investigating intermediate length scales by small angle laser light scattering. J Chem Phys 2015; 143:064903. [DOI: 10.1063/1.4928370] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Richard Beyer
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | - Markus Franke
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | | | - Eckhard Bartsch
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität, D-79104 Freiburg, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
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29
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Kozina A, Díaz-Leyva P, Palberg T, Bartsch E. Crystallization kinetics of colloidal binary mixtures with depletion attraction. Soft Matter 2014; 10:9523-9533. [PMID: 25354340 DOI: 10.1039/c4sm02193b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work the crystallization kinetics of colloidal binary mixtures with attractive interaction potential (Asakura-Oosawa) has been addressed. Parameters such as fraction of crystals, linear crystal dimension and crystal packing have been quantified in order to understand how the crystal formation is driven in terms of the depth of the attractive potential and the composition of the binary mixture (described by the number ratio). It was found that inside the eutectic triangle, crystallization is mainly governed by nucleation and the crystal packing is close to the close-packing of hard spheres. Moving out from the eutectic triangle towards small component results in the crystallization of small spheres. Enrichment of the eutectic mixture with large component results in the crystallization of both large and small spheres, however, the kinetics are completely different from those of the eutectic composition. Crosslinked polystyrene microgels with nearly hard sphere interactions were used as model systems. Attraction was introduced by addition of linear polystyrene. The time evolution of crystallization has been followed by static light scattering.
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Affiliation(s)
- Anna Kozina
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str. 31, 79104 Freiburg, Germany.
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30
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Hornfeck W, Menke D, Forthaus M, Subatzus S, Franke M, Schöpe HJ, Palberg T, Perlich J, Herlach D. Nucleation and crystal growth in a suspension of charged colloidal silica spheres with bi-modal size distribution studied by time-resolved ultra-small-angle X-ray scattering. J Chem Phys 2014; 141:214906. [PMID: 25481168 DOI: 10.1063/1.4902904] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Wolfgang Hornfeck
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Dirk Menke
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Martin Forthaus
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Sebastian Subatzus
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
| | - Markus Franke
- Institut für Physik, Johannes-Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - Hans-Joachim Schöpe
- Institut für Physik, Johannes-Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - Thomas Palberg
- Institut für Physik, Johannes-Gutenberg-Universität, Staudingerweg 7, 55128 Mainz, Germany
| | - Jan Perlich
- Deutsches Elektronensynchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany
| | - Dieter Herlach
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany
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31
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Abstract
Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions, with rather well-characterized pair interactions and minimized external influences. In complementary approaches experiment, analytic theory and simulation have been employed to study colloidal solidification in great detail. These studies were based on advanced optical methods, careful system characterization and sophisticated numerical methods. Over the last decade, both the effects of the type, strength and range of the pair-interaction between the colloidal particles and those of the colloid-specific polydispersity have been addressed in a quantitative way. Key parameters of crystallization have been derived and compared to those of metal systems. These systematic investigations significantly contributed to an enhanced understanding of the crystallization processes in general. Further, new fundamental questions have arisen and (partially) been solved over the last decade: including, for example, a two-step nucleation mechanism in homogeneous nucleation, choice of the crystallization pathway, or the subtle interplay of boundary conditions in heterogeneous nucleation. On the other hand, via the application of both gradients and external fields the competition between different nucleation and growth modes can be controlled and the resulting microstructure be influenced. The present review attempts to cover the interesting developments that have occurred since the turn of the millennium and to identify important novel trends, with particular focus on experimental aspects.
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Affiliation(s)
- Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany
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32
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Heinen M, Palberg T, Löwen H. Coupling between bulk- and surface chemistry in suspensions of charged colloids. J Chem Phys 2014; 140:124904. [DOI: 10.1063/1.4869338] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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Reinmüller A, Palberg T, Schöpe HJ. Charged colloidal model systems under confinement in slit geometry: a new setup for optical microscopic studies. Rev Sci Instrum 2013; 84:063907. [PMID: 23822357 DOI: 10.1063/1.4811719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A new experimental setup for optical microscopic studies of charged colloidal model systems under confinement between two flat walls is presented. The measurement cell consists of optically flat quartz substrates attached to piezo actuators. Those facilitate fast and flexible adjustment of the confining geometry. Optionally, the local cell height can be quantitatively controlled by in situ interferometric measurements. Proper choice of materials guarantees sufficient chemical inertia against contamination with salt ions. For efficient preparation of charged colloidal suspensions under strongly deionized conditions, the cell can be connected to a conventional pump circuit including a mixed bed ion exchanger column. The usefulness of this setup, in particular for investigating the equilibrium phase behavior of colloids at low background salt concentrations, is demonstrated recalling recent experiments.
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Affiliation(s)
- A Reinmüller
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7 55128 Mainz, Germany.
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34
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Abstract
Investigations of swimming at low Reynolds numbers (Re < 10(-4)) so far have focused on individual or collectively moving autonomous microswimmers consisting of a single active building unit. Here we show that linear propulsion can also be reproducibly generated in a self-assembled dynamic complex formed from a granular, HCl-releasing particle settled on a charged quartz wall and a swarm of micrometer-sized negatively charged colloids. In isolation, none of the constituents shows motion beyond diffusion. When brought together, they self-assemble into a complex capable of directed swimming. It is stabilized by toroidal solvent flow centered about the granular particle. Propulsion is then launched by an asymmetric distribution of the colloids. Motion is self-stabilizing and continues for up to 25 min with velocities of 1-3 μm/s. Although the details of the mechanisms involved pose a formidable experimental and theoretical challenge, our observations offer a conceptually new, well-reproduced, versatile approach to swimming and transport at low Reynolds numbers.
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Affiliation(s)
- Alexander Reinmüller
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 7, 55128 Mainz, Germany
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35
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Palberg T, Maaroufi MR, Stipp A, Schöpe HJ. Micro-structure evolution of wall based crystals after casting of model suspensions as obtained from Bragg microscopy. J Chem Phys 2013; 137:094906. [PMID: 22957593 DOI: 10.1063/1.4749261] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Growth of heterogeneously nucleated, wall based crystals plays a major role in determining the micro-structure during melt casting. This issue is here addressed using a model system of charged colloidal spheres in deionized aqueous suspension observed by Bragg microscopy which is a combination of light scattering and microscopy. We examine the evolution of the three-dimensional size, shape, and orientation of twin domains in monolithic crystals growing from two opposing planar walls into a meta-stable (shear-) melt. At each wall crystal orientation and twinning emerges during nucleation with small domains. During growth these widen and merge. From image analysis we observe the lateral coarsening velocities to follow a power law behaviour L(XY) ∝ t(1/2) as long as the vertical growth continues at constant speed. Lateral coarsening terminates upon intersection of the two solids and hardly any further ripening is seen. Initial lateral coarsening velocities show a Wilson Frenkel type dependence on the melt meta-stability.
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Affiliation(s)
- Thomas Palberg
- University of Mainz, Institute of Physics, Staudingerweg 7, D-55099 Mainz, Germany.
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36
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Oğuz EC, Reinmüller A, Schöpe HJ, Palberg T, Messina R, Löwen H. Crystalline multilayers of charged colloids in soft confinement: experiment versus theory. J Phys Condens Matter 2012; 24:464123. [PMID: 23114225 DOI: 10.1088/0953-8984/24/46/464123] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We combine real-space experiments and lattice sum calculations to investigate the phase diagram of charged colloidal particles under soft confinement. In the experiments we explore the equilibrium phase diagram of charged colloidal spheres in aqueous suspensions confined between two parallel charged walls at low background salt concentrations. Motivated by the experiments, we perform lattice sum minimizations to predict the crystalline ground state of point-like Yukawa particles which are exposed to a soft confining wall potential. In the multilayered crystalline regime, we obtain good agreement between the experimental and numerical findings: upon increasing the density we recover the sequence [structure: see text].
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Affiliation(s)
- E C Oğuz
- Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
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37
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Palberg T, Köller T, Sieber B, Schweinfurth H, Reiber H, Nägele G. Electro-kinetics of charged-sphere suspensions explored by integral low-angle super-heterodyne laser Doppler velocimetry. J Phys Condens Matter 2012; 24:464109. [PMID: 23113974 DOI: 10.1088/0953-8984/24/46/464109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigated the flow behaviour of colloidal charged-sphere suspensions using a newly designed integral low-angle super-heterodyne laser Doppler velocimetry instrument, which combines the advantages of several previous approaches. Sample conditions ranged from strong electrostatic interactions with pronounced short-range order to individual particles with no spatial correlations. The obtained power spectra correspond to diffusion broadened velocity distributions across the complete sample cross section. The excellent performance of the instrument is highlighted in detail by the example of electro-kinetic flow of suspensions in a closed cell of a rectangular cross section. We demonstrate the excellent performance of our approach with the example of electro-phoretic-electro-osmotic experiments, showing that a comprehensive flow characterization becomes possible by analysing the measured electro-kinetic mobilities, the flow-profile, an effective diffusion coefficient and the integrated scattering density. We briefly discuss present limitations, possible extensions and interesting applications in other fields.
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Affiliation(s)
- Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität, D-55128 Mainz, Germany.
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Beyer R, Iacopini S, Palberg T, Schöpe HJ. Polymer induced changes of the crystallization scenario in suspensions of hard sphere like microgel particles. J Chem Phys 2012; 136:234906. [DOI: 10.1063/1.4729562] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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39
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Reinmüller A, Oğuz EC, Messina R, Löwen H, Schöpe HJ, Palberg T. Colloidal crystallization in the quasi-two-dimensional induced by electrolyte gradients. J Chem Phys 2012; 136:164505. [DOI: 10.1063/1.4705393] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Palberg T, Löwen H. Colloidal and molecular electro-optics. J Phys Condens Matter 2010; 22:490301. [PMID: 21422510 DOI: 10.1088/0953-8984/22/49/490301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität Mainz, Staudinger Weg 7, 55128 Mainz, Germany
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41
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Lorenz NJ, Palberg T. Melting and freezing lines for a mixture of charged colloidal spheres with spindle-type phase diagram. J Chem Phys 2010; 133:104501. [DOI: 10.1063/1.3487523] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Stipp A, Schöpe HJ, Palberg T, Eckert T, Biehl R, Bartsch E. Optical experiments on a crystallizing hard-sphere-polymer mixture at coexistence. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:051401. [PMID: 20866224 DOI: 10.1103/physreve.81.051401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Indexed: 05/29/2023]
Abstract
We report on the crystallization kinetics in an entropically attractive colloidal system using a combination of time resolved scattering methods and microscopy. Hard sphere particles are polystyrene microgels swollen in a good solvent (radius a=380 nm, starting volume fraction 0.534) with the short ranged attractions induced by the presence of short polymer chains (radius of gyration r g=3 nm, starting volume fraction 0.0224). After crystallization, stacking faulted face centered cubic crystals coexist with about 5% of melt remaining in the grain boundaries. From the Bragg scattering signal we infer the amount of crystalline material, the average crystallite size and the number density of crystals as a function of time. This allows to discriminate an early stage of conversion, followed by an extended coarsening stage. The small angle scattering (SALS) appears only long after completed conversion and exhibits Furukawa scaling for all times. Additional microscopic experiments reveal that the grain boundaries have a reduced Bragg scattering power but possess an increased refractive index. Fits of the Furukawa function indicate that the dimensionality of the scatterers decreases from 2.25 at short times to 1.65 at late times and the characteristic length scale is slightly larger than the average crystallite size. Together this suggests the SALS signal is due scattering from a foam like grain boundary network as a whole.
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Affiliation(s)
- Andreas Stipp
- Institut für Physik, Johannes Gutenberg Universität, Staudingerweg 7, D-55128 Mainz, Germany
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43
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Wette P, Klassen I, Holland-Moritz D, Herlach DM, Schöpe HJ, Lorenz N, Reiber H, Palberg T, Roth SV. Communications: Complete description of re-entrant phase behavior in a charge variable colloidal model system. J Chem Phys 2010; 132:131102. [DOI: 10.1063/1.3380823] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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44
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Lorenz NJ, Schöpe HJ, Reiber H, Palberg T, Wette P, Klassen I, Holland-Moritz D, Herlach D, Okubo T. Phase behaviour of deionized binary mixtures of charged colloidal spheres. J Phys Condens Matter 2009; 21:464116. [PMID: 21715880 DOI: 10.1088/0953-8984/21/46/464116] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios Γ and charge ratios Λ are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration. Depending on Γ and Λ, we observe upper azeotrope, spindle, lower azeotrope and eutectic types of phase diagrams, all known well from metal systems. Most solids are of body centred cubic structure. Occasionally stoichiometric compounds are formed at large particle concentrations. For very low Γ, entropic effects dominate and induce a fluid-fluid phase separation. Since for charged spheres the charge ratio Λ is also decisive for the type of phase diagram, future experiments with charge variable silica spheres are suggested.
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Affiliation(s)
- Nina J Lorenz
- Institut für Physik, Johannes Gutenberg Universität Mainz, Staudinger Weg 7, D-55128 Mainz, Germany
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Lorenz NJ, Schöpe HJ, Palberg T. Phase behavior of a de-ionized binary mixture of charged spheres in the presence of gravity. J Chem Phys 2009; 131:134501. [DOI: 10.1063/1.3225339] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Wette P, Schöpe HJ, Palberg T. Enhanced crystal stability in a binary mixture of charged colloidal spheres. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:021407. [PMID: 19792124 DOI: 10.1103/physreve.80.021407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/25/2009] [Indexed: 05/28/2023]
Abstract
We report on the phase behavior of a binary charged sphere mixture of size ratio Gamma=0.68 and charge ratio Lambda approximately 1 as a function of composition p and number density n . For p=0.1-0.3 we observe freezing at densities well below the freezing densities of the pure components. At all compositions our data indicate the formation of substitutional alloy crystals of body centered cubic structure. No indications for compound formation were observed. Rather, our findings point at the first observation of an upper azeotrope. Measurements of the crystallization kinetics reveal a combined density and composition dependence of growth velocities and nucleation rate densities, with small but significant anomalies at p*=0.2 . These correlated deviations can be rationalized within classical theories of solidification and suggest an increased similarity between melt and solid for this particular composition.
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Affiliation(s)
- Patrick Wette
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, 51170 Köln, Germany
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47
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Iacopini S, Palberg T, Schöpe HJ. Crystallization kinetics of polydisperse hard-sphere-like microgel colloids: Ripening dominated crystal growth above melting. J Chem Phys 2009; 130:084502. [DOI: 10.1063/1.3078310] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Palberg T, Stipp A, Bartsch E. Unusual crystallization kinetics in a hard sphere colloid-polymer mixture. Phys Rev Lett 2009; 102:038302. [PMID: 19257401 DOI: 10.1103/physrevlett.102.038302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Indexed: 05/27/2023]
Abstract
We investigated the crystallization kinetics of a hard sphere colloid-polymer mixture at conditions where about 95% of solid coexists with about 5% of fluid. From time resolved Bragg and small angle light scattering, we find that the crystallite size increases with a power law of exponent alpha approximately 1/3 during both the conversion and the coarsening stage. This observation points to a single conserved order parameter for both stages and cannot be explained if the mixture is regarded as an effective one-component system. We alternatively suggest that--based on local geometric demixing--the polymer density takes the role of the conserved order parameter.
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Affiliation(s)
- Thomas Palberg
- Johannes Gutenberg Universität, Institut für Physik, Staudingerweg 7, D-55128 Mainz, Germany
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49
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Iacopini S, Palberg T, Schöpe HJ. Ripening-dominated crystallization in polydisperse hard-sphere-like colloids. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:010601. [PMID: 19256993 DOI: 10.1103/physreve.79.010601] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 11/06/2008] [Indexed: 05/27/2023]
Abstract
We report on the crystal growth scenario in gravity-matched, polydisperse hard-sphere-like colloids at increasing particle concentration. In the fluid-crystal coexistence region, the crystal size as a function of time shows two separate regimes corresponding to crystal growth and crystal ripening. At higher supersaturation the crystal size grows according to the same power law through the whole experimental window of a few days: crystal growth and ripening merge together. We show that our observations cannot be explained by considering the slowing down of single-particle dynamics due to increasing volume fraction. We suggest that size fractionation occurring at the crystal-fluid interface is the dominant mechanism.
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Affiliation(s)
- Sara Iacopini
- Institut für Physik, Johannes Gutenberg Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
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50
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Wette P, Klassen I, Holland-Moritz D, Palberg T, Roth SV, Herlach DM. Colloids as model systems for liquid undercooled metals. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:010501. [PMID: 19256992 DOI: 10.1103/physreve.79.010501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Indexed: 05/27/2023]
Abstract
Charged colloidal particles interact via a hard core Yukawa potential, while isotropic Lennard-Jones-like potentials are frequently used as pair potentials in metals. We present measurements of the structure factor of shear molten monodisperse colloids and molten metals using ultrasmall-angle x-ray scattering and elastic neutron scattering, respectively. In both systems data analysis gives evidence of fivefold-symmetric short-range order becoming more pronounced with increasing deviations from equilibrium. The experiments demonstrate that in both systems topological effects control ordering in the melt state.
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Affiliation(s)
- Patrick Wette
- Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, 51170 Köln, Germany
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