1
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El Rifaii K, Wensink HH, Goldmann C, Michot L, Gabriel JCP, Davidson P. Fine tuning the structural colours of photonic nanosheet suspensions by polymer doping. SOFT MATTER 2021; 17:9280-9292. [PMID: 34633014 DOI: 10.1039/d1sm00907a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Aqueous suspensions of nanosheets are readily obtained by exfoliating low-dimensional mineral compounds like H3Sb3P2O14. The nanosheets self-organize, at low concentration, into a periodic stack of membranes, i.e. a lamellar liquid-crystalline phase. Due to the dilution, this stack has a large period of a few hundred nanometres, it behaves as a 1-dimensional photonic material and displays structural colours. We experimentally investigated the dependence of the period on the nanosheet concentration. We theoretically showed that it cannot be explained by the usual DLVO interaction between uniform lamellae but that the particulate nature of nanosheet-laden membranes must be considered. Moreover, we observed that adding small amounts of 100 kDa poly(ethylene oxide) (PEO) decreases the period and allows tuning the colour throughout the visible range. PEO adsorbs on the nanosheets, inducing a strong reduction of the nanosheet charge. This is probably due to the Lewis-base character of the EO units of PEO that become protonated at the low pH of the system, an interpretation supported by theoretical modeling. Oddly enough, adding small amounts of 1 MDa PEO has the opposite effect of increasing the period, suggesting the presence of an additional intermembrane repulsion not yet identified. From an applied perspective, our work shows how the colours of these 1-dimensional photonic materials can easily be tuned not only by varying the nanosheet concentration (which might entail a phase transition) but also by adding PEO. From a theoretical perspective, our approach represents a necessary step towards establishing the phase diagram of aqueous suspensions of charged nanosheets.
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Affiliation(s)
- Karin El Rifaii
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France.
| | - Henricus H Wensink
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France.
| | - Claire Goldmann
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France.
| | - Laurent Michot
- Laboratory of Physical Chemistry of Electrolytes and Interfacial Nanosystems (PHENIX), Sorbonne Université, CNRS, 75005 Paris, France
| | | | - Patrick Davidson
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France.
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2
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Experimental study on reversible formation of 2D flocs from plate-like particles dispersed in Newtonian fluid under torsional flow. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.03.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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3
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García ÁG, Tuinier R, Maring JV, Opdam J, Wensink HH, Lekkerkerker HNW. Depletion-driven four-phase coexistences in discotic systems. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1463471] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Álvaro González García
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Remco Tuinier
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Jasper V. Maring
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Joeri Opdam
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Henricus H. Wensink
- Laboratoire de Physique des Solides - UMR 8502, Université Paris-Sud, Université Paris-Saclay and CNRS , Orsay, France
| | - Henk N. W. Lekkerkerker
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
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Sokolova E, Vlasov A, Venediktova A. Biaxial nematic stability in the rod-plate mixture with a dopant: The restricted-orientation model on the 3rd virial level. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.04.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Jabbari-Farouji S, Weis JJ, Davidson P, Levitz P, Trizac E. Interplay of anisotropy in shape and interactions in charged platelet suspensions. J Chem Phys 2015; 141:224510. [PMID: 25494763 DOI: 10.1063/1.4903045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Motivated by the intriguing phase behavior of charged colloidal platelets, we investigate the structure and dynamics of charged repulsive disks by means of Monte Carlo simulations. The electrostatic interactions are taken into account through an effective two-body potential, obtained within the nonlinear Poisson-Boltzmann formalism, which has the form of anisotropic screened Coulomb potential. Recently, we showed that the original intrinsic anisotropy of the electrostatic potential in competition with excluded volume effects leads to a rich phase behavior that not only includes various liquid-crystalline phases but also predicts the existence of novel structures composed of alternating nematic-antinematic sheets. Here, we examine the structural and dynamical signatures of each of the observed structures for both translational and rotational degrees of freedom. Finally, we discuss the influence of effective charge value and our results in relation to experimental findings on charged platelet suspensions.
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Affiliation(s)
- Sara Jabbari-Farouji
- LPTMS, CNRS and Université Paris-Sud, UMR8626, Bat. 100, 91405 Orsay, France and Laboratoire Interdisciplinaire de Physique, UMR 5588, F-38041 Grenoble, France
| | - Jean-Jacques Weis
- Laboratoire de Physique Théorique, Université Paris-Sud, UMR 8627 Bâtiment 210, 91405 Orsay Cedex, France
| | - Patrick Davidson
- Laboratoire de Physique des Solides, Université Paris-Sud, UMR 8502 Bâtiment 510, 91405 Orsay Cedex, France
| | - Pierre Levitz
- Laboratoire PECSA, UMR 7195, Université Pierre et Marie Curie, Case Courrier 51, 4 place Jussieu, 72522 Paris Cedex 5, France
| | - Emmanuel Trizac
- LPTMS, CNRS and Université Paris-Sud, UMR8626, Bat. 100, 91405 Orsay, France
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6
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Wensink HH, Trizac E. Generalized Onsager theory for strongly anisometric patchy colloids. J Chem Phys 2014; 140:024901. [PMID: 24437905 DOI: 10.1063/1.4851217] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The implications of soft "patchy" interactions on the orientational disorder-order transition of strongly elongated colloidal rods and flat disks is studied within a simple Onsager-van der Waals density functional theory. The theory provides a generic framework for studying the liquid crystal phase behaviour of highly anisometric cylindrical colloids which carry a distinct geometrical pattern of repulsive or attractive soft interactions localized on the particle surface. In this paper, we apply our theory to the case of charged rods and disks for which the local electrostatic interactions can be described by a screened-Coulomb potential. We consider infinitely thin rod like cylinders with a uniform line charge and infinitely thin discotic cylinders with several distinctly different surface charge patterns. Irrespective of the backbone shape the isotropic-nematic phase diagrams of charged colloids feature a generic destabilization of nematic order at low ionic strength, a dramatic narrowing of the biphasic density region, and a reentrant phenomenon upon reducing the electrostatic screening. The low screening regime is characterized by a complete suppression of nematic order in favor of positionally ordered liquid crystal phases.
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Affiliation(s)
- H H Wensink
- Laboratoire de Physique des Solides - UMR 8502, Université Paris-Sud and CNRS, 91405 Orsay Cedex, France
| | - E Trizac
- Laboratoire de Physique Théorique et Modèles Statistiques - UMR 8626, Université Paris-Sud and CNRS, 91405 Orsay Cedex, France
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7
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Ahmad I, Zandvliet HJW, Kooij ES. Shape-induced separation of nanospheres and aligned nanorods. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7953-7961. [PMID: 24959664 DOI: 10.1021/la500980j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods exhibit a strong preference for side-by-side alignment, giving rise to smectic phases; spheres in solution are forced out of these regions and form close-packed arrays. We discuss this self-separation into nanorod- and sphere-rich phases in terms of various interactions, including electrostatic, van der Waals, and deplection interactions forces. The experimental results are compared to quantitative calculations of the colloidal interaction energies. We also describe and discuss the role of the surfactant on the different crystal facets of the nanorods on the assembly process.
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Affiliation(s)
- I Ahmad
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, NL-7500AE Enschede, The Netherlands
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8
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Nakato T, Yamashita Y, Mouri E, Kuroda K. Multiphase coexistence and destabilization of liquid crystalline binary nanosheet colloids of titanate and clay. SOFT MATTER 2014; 10:3161-5. [PMID: 24658592 DOI: 10.1039/c3sm52311j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A plate-plate binary colloid system of photocatalytically active titanate and inert clay nanosheets shows macroscopically separated multiphase coexistence. Two liquid crystalline phases and one isotropic phase coexist at high titanate and low clay concentrations whereas the colloids are destabilized at high clay concentrations.
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Affiliation(s)
- Teruyuki Nakato
- Department of Applied Chemistry, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu-shi, Fukuoka 804-8550, Japan.
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Chen X, Gao H, Ploehn HJ. Montmorillonite–levan nanocomposites with improved thermal and mechanical properties. Carbohydr Polym 2014; 101:565-73. [DOI: 10.1016/j.carbpol.2013.09.073] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 09/18/2013] [Accepted: 09/21/2013] [Indexed: 11/28/2022]
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11
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de las Heras D, Schmidt M. Bulk fluid phase behaviour of colloidal platelet-sphere and platelet-polymer mixtures. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120259. [PMID: 23459962 DOI: 10.1098/rsta.2012.0259] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Using a geometry-based fundamental measure density functional theory, we calculate bulk fluid phase diagrams of colloidal mixtures of vanishingly thin hard circular platelets and hard spheres. We find isotropic-nematic phase separation, with strong broadening of the biphasic region, upon increasing the pressure. In mixtures with large size ratio of platelet and sphere diameters, there is also demixing between two nematic phases with differing platelet concentrations. We formulate a fundamental measure density functional for mixtures of colloidal platelets and freely overlapping spheres, which represent ideal polymers, and use it to obtain phase diagrams. We find that, for low platelet-polymer size ratio, in addition to isotropic-nematic and nematic-nematic phase coexistence, platelet-polymer mixtures also display isotropic-isotropic demixing. By contrast, we do not find isotropic-isotropic demixing in hard-core platelet-sphere mixtures for the size ratios considered.
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Affiliation(s)
- Daniel de las Heras
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth, Germany.
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12
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Rosenfeldt S, Lüdel F, Schulreich C, Hellweg T, Radulescu A, Schmelz J, Schmalz H, Harnau L. Patchy worm-like micelles: solution structure studied by small-angle neutron scattering. Phys Chem Chem Phys 2013; 14:12750-6. [PMID: 22880203 DOI: 10.1039/c2cp41231d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Triblock terpolymers exhibit a rich self-organization behavior including the formation of fascinating cylindrical core-shell structures with a phase separated corona. After crystallization-induced self-assembly of polystyrene-block-polyethylene-block-poly(methyl methacrylate) triblock terpolymers (abbreviated as SEMs = Styrene-Ethylene-Methacrylates) from solution, worm-like core-shell micelles with a patchy corona of polystyrene and poly(methyl methacrylate) were observed by transmission electron microscopy. However, the solution structure is still a matter of debate. Here, we present a method to distinguish in situ between a Janus-type (two faced) and a patchy (multiple compartments) configuration of the corona. To discriminate between both models the scattering intensity must be determined mainly by one corona compartment. Contrast variation in small-angle neutron scattering enables us to focus on one compartment of the worm-like micelles. The results validate the existence of the patchy structure also in solution.
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Affiliation(s)
- Sabine Rosenfeldt
- Physikalische Chemie I, Universität Bayreuth, D-95440 Bayreuth, Germany
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13
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Shuai M, Mejia AF, Chang YW, Cheng Z. Hydrothermal synthesis of layered α-zirconium phosphate disks: control of aspect ratio and polydispersity for nano-architecture. CrystEngComm 2013. [DOI: 10.1039/c2ce26402a] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Floating nematic phase in colloidal platelet-sphere mixtures. Sci Rep 2012; 2:789. [PMID: 23145313 PMCID: PMC3494036 DOI: 10.1038/srep00789] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/09/2012] [Indexed: 11/08/2022] Open
Abstract
The phase behaviour of colloidal dispersions is interesting for fundamental reasons and for technological applications such as photonic crystals and electronic paper. Sedimentation, which in everyday life is relevant from blood analysis to the shelf life of paint, is a means to determine phase boundaries by observing distinct layers in samples that are in sedimentation-diffusion equilibrium. However, disentangling the effects due to interparticle interactions, which generate the bulk phase diagram, from those due to gravity is a complex task. Here we show that a line in the space of chemical potentials µ(i), where i labels the species, represents a sedimented sample and that each crossing of this sedimentation path with a binodal generates an interface under gravity. Complex phase stacks can result, such as the sandwich of a floating nematic layer between top and bottom isotropic phases that we observed in a mixture of silica spheres and gibbsite platelets.
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Bolisetty S, Harnau L, Jung JM, Mezzenga R. Gelation, Phase Behavior, and Dynamics of β-Lactoglobulin Amyloid Fibrils at Varying Concentrations and Ionic Strengths. Biomacromolecules 2012; 13:3241-52. [DOI: 10.1021/bm301005w] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sreenath Bolisetty
- ETH Zurich, Food
and Soft Materials Laboratory, Department of Health Science
and Technology, Schmelzbergstrasse 9, LFO-E22, CH-8092 Zurich, Switzerland
| | - Ludger Harnau
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3,
70569 Stuttgart, Germany, and Institut für Theoretische und
Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57,
70569 Stuttgart, Germany
| | - Jin-mi Jung
- Department of Physics, University of Fribourg, Ch. Musée 3, CH-1700
Fribourg, Switzerland
| | - Raffaele Mezzenga
- ETH Zurich, Food
and Soft Materials Laboratory, Department of Health Science
and Technology, Schmelzbergstrasse 9, LFO-E22, CH-8092 Zurich, Switzerland
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16
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Fartaria RP, Javid N, Sefcik J, Sweatman MB. Simulation of scattering and phase behavior around the isotropic–nematic transition of discotic particles. J Colloid Interface Sci 2012; 377:94-104. [DOI: 10.1016/j.jcis.2012.03.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022]
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17
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Wu L, Wensink H, Jackson G, Müller E. A generic equation of state for liquid crystalline phases of hard-oblate particles. Mol Phys 2012. [DOI: 10.1080/00268976.2011.649794] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Mathew M, Schilling T, Oettel M. Connectivity percolation in suspensions of hard platelets. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061407. [PMID: 23005096 DOI: 10.1103/physreve.85.061407] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Indexed: 06/01/2023]
Abstract
We present a study on connectivity percolation in suspensions of hard platelets by means of Monte Carlo simulation. We interpret our results using a contact-volume argument based on an effective single-particle cell model. It is commonly assumed that the percolation threshold of anisotropic objects scales as their inverse aspect ratio. While this rule has been shown to hold for rodlike particles, we find that for hard platelike particles the percolation threshold is nonmonotonic in the aspect ratio. It exhibits a shallow minimum at intermediate aspect ratios and then saturates to a constant value. This effect is caused by the isotropic-nematic transition preempting the percolation transition. Hence the common strategy to use highly anisotropic, conductive particles as fillers in composite materials in order to produce conduction at low filler concentration is expected to fail for platelike fillers such as graphene and graphite nanoplatelets.
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Affiliation(s)
- Maneesh Mathew
- Institut für Physik, Johannes-Gutenberg-Universität, Staudinger Weg 7, D-55099 Mainz, Germany.
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19
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Delhorme M, Labbez C, Jönsson B. Liquid Crystal Phases in Suspensions of Charged Plate-Like Particles. J Phys Chem Lett 2012; 3:1315-20. [PMID: 26286776 DOI: 10.1021/jz300380n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Anisotropic interactions in colloidal suspensions have recently emerged as a route for the design of new soft materials. Nonisotropic particles can form nematic, smectic, hexatic, and columnar liquid crystals. Although the formation of these phases is well rationalized when excluded volume is solely at play, the role of electrostatic interactions still remains unclear and even less so when particles present a charge heterogeneity, for example, clays. Here, we use Monte Carlo simulations of concentrated suspensions of charged disk-like particles to reveal the role of Coulomb interactions and charge anisotropy underlying liquid crystal formation and structures. We observe a vast zoo of exotic structures, going from hexatic to columnar phases, which are shown to be controlled by the charge anisotropy. The particle volume fraction at which these phases start to form is found to decrease with increasing Coulomb interactions and charge anisotropy, which suggests a route to tune the structure of aqueous liquid crystals.
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Affiliation(s)
- Maxime Delhorme
- †Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne, 21078 Dijon Cedex, France
| | - Christophe Labbez
- †Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne, 21078 Dijon Cedex, France
| | - Bo Jönsson
- ‡Department of Theoretical Chemistry, Chemical Center, POB 124, S-221 00 Lund, Sweden
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Rochette CN, Rosenfeldt S, Henzler K, Polzer F, Ballauff M, Tong Q, Mecking S, Drechsler M, Narayanan T, Harnau L. Annealing of Single Lamella Nanoparticles of Polyethylene. Macromolecules 2011. [DOI: 10.1021/ma2003213] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Sabine Rosenfeldt
- Physikalische Chemie I, University of Bayreuth, 95440 Bayreuth, Germany
| | - Katja Henzler
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - Frank Polzer
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - Qiong Tong
- Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
| | - Stefan Mecking
- Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
| | - Markus Drechsler
- Makromolekulare Chemie II, University of Bayreuth, 95440 Bayreuth, Germany
| | | | - Ludger Harnau
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany, and Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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Phillips J, Schmidt M. Phase behaviour of binary mixtures of diamagnetic colloidal platelets in an external magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:194111. [PMID: 21525550 DOI: 10.1088/0953-8984/23/19/194111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Using fundamental measure density functional theory we investigate paranematic-nematic and nematic-nematic phase coexistence in binary mixtures of circular platelets with vanishing thicknesses. An external magnetic field induces uniaxial alignment and acts on the platelets with a strength that is taken to scale with the platelet area. At particle diameter ratio λ = 1.5 the system displays paranematic-nematic coexistence. For λ = 2, demixing into two nematic states with different compositions also occurs, between an upper critical point and a paranematic-nematic-nematic triple point. Increasing the field strength leads to shrinking of the coexistence regions. At high enough field strength a closed loop of immiscibility is induced and phase coexistence vanishes at a double critical point above which the system is homogeneously nematic. For λ = 2.5, besides paranematic-nematic coexistence, there is nematic-nematic coexistence which persists and hence does not end in a critical point. The partial orientational order parameters along the binodals vary strongly with composition and connect smoothly for each species when closed loops of immiscibility are present in the corresponding phase diagram.
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Affiliation(s)
- Jonathan Phillips
- H H Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol, UK
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22
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Zettl U, Ballauff M, Harnau L. A fluorescence correlation spectroscopy study of macromolecular tracer diffusion in polymer solutions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:494111. [PMID: 21406777 DOI: 10.1088/0953-8984/22/49/494111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We discuss the manner in which the dynamics of tracer polystyrene chains varies with the concentration of matrix polystyrene chains dissolved in toluene. Using fluorescence correlation spectroscopy and theory, it is shown that the cooperative diffusion coefficient of the matrix polystyrene chains can be measured by fluorescence correlation spectroscopy in the semidilute entangled concentration regime. In addition the self-diffusion coefficient of the tracer polystyrene chains can be detected for arbitrary concentrations. The measured cooperative diffusion coefficient is independent of the molecular weight of the tracer polystyrene chains because it is a characteristic feature of the transient entanglement network.
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Affiliation(s)
- Ute Zettl
- Physikalische Chemie I, University of Bayreuth, 95440 Bayreuth, Germany
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23
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Satoh A, Aoshima M. 3D Monte Carlo simulations of a magnetic disk-like particle dispersion. Colloid Polym Sci 2010. [DOI: 10.1007/s00396-010-2320-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Byelov DV, Mourad MCD, Snigireva I, Snigirev A, Petukhov AV, Lekkerkerker HNW. Experimental observation of fractionated crystallization in polydisperse platelike colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:6898-6901. [PMID: 20392119 DOI: 10.1021/la100993k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have discovered that the long-term aging of the hexagonal columnar liquid-crystal phase of polydisperse gibbsite platelets leads to fractionated crystallization, that is, to the formation of coexisting columnar crystals with different periods. This process was revealed by microradian X-ray diffraction demonstrating the splitting of the Bragg intercolumnar reflections into sequences of sharper reflections. The fractionated crystallization was observed in a number of samples of sterically stabilized as well as charge-stabilized polydisperse gibbsite platelets.
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Affiliation(s)
- D V Byelov
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
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Phillips J, Schmidt M. Bulk phase behavior of binary hard platelet mixtures from density functional theory. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:041401. [PMID: 20481721 DOI: 10.1103/physreve.81.041401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Indexed: 05/29/2023]
Abstract
We investigate isotropic-isotropic, isotropic-nematic, and nematic-nematic phase coexistence in binary mixtures of circular platelets with vanishing thickness, continuous rotational degrees of freedom, and radial size ratios lambda up to 5. A fundamental measure density functional theory, previously used for the one-component model, is presented and results are compared against those from Onsager theory as a benchmark. For lambda<or=1.7 the system displays isotropic-nematic phase coexistence with a widening of the biphasic region for increasing values of lambda . For size ratios lambda>or=2, we find that demixing into two nematic states becomes stable and an isotropic-nematic-nematic triple point can occur. Fundamental measure theory gives a smaller isotropic-nematic biphasic region than Onsager theory and locates the transition at lower densities. Furthermore, nematic-nematic demixing occurs over a larger range of compositions at a given value of lambda than found in Onsager theory. Both theories predict the same topologies of the phase diagrams. The partial nematic order parameters vary strongly with composition and indicate that the larger particles are more strongly ordered than the smaller particles.
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Affiliation(s)
- Jonathan Phillips
- H.H. Wills Physics Laboratory, Bristol University, Royal Fort, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
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Munaò G, Costa D, Saija F, Caccamo C. Simulation and reference interaction site model theory of methanol and carbon tetrachloride mixtures. J Chem Phys 2010; 132:084506. [DOI: 10.1063/1.3314296] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Zettl U, Hoffmann ST, Koberling F, Krausch G, Enderlein J, Harnau L, Ballauff M. Self-Diffusion and Cooperative Diffusion in Semidilute Polymer Solutions As Measured by Fluorescence Correlation Spectroscopy. Macromolecules 2009. [DOI: 10.1021/ma901404g] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ute Zettl
- Physikalische Chemie I, University of Bayreuth, D-95440 Bayreuth, Germany
| | | | | | | | - Jörg Enderlein
- Institute of Physics, Georg August University, D-37077 Göttingen, Germany
| | - Ludger Harnau
- Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart, Germany
- Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
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Satoh A, Sakuda Y. Quasi-2D Monte Carlo simulations of a colloidal dispersion composed of magnetic plate-like particles with magnetic moment normal to the particle axis. Mol Phys 2009. [DOI: 10.1080/00268970902994301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Rosenfeldt S, Ballauff M, Lindner P, Harnau L. Structure and interaction of flexible dendrimers in concentrated solution. J Chem Phys 2009; 130:244901. [DOI: 10.1063/1.3155208] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Munaò G, Costa D, Caccamo C. Reference interaction site model investigation of homonuclear hard dumbbells under simple fluid theory closures: Comparison with Monte Carlo simulations. J Chem Phys 2009; 130:144504. [DOI: 10.1063/1.3098551] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Munaò G, Costa D, Caccamo C. Thermodynamically consistent reference interaction site model theory of the tangent diatomic fluid. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.01.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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