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Martín-Martín S, Ramos-Tejada MDM, Rubio-Andrés A, Bonhome-Espinosa AB, Delgado ÁV, Jiménez ML. Electro-optical Study of the Anomalous Rotational Diffusion in Polymer Solutions. Macromolecules 2023; 56:518-527. [PMID: 36711111 PMCID: PMC9879198 DOI: 10.1021/acs.macromol.2c01461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/22/2022] [Indexed: 01/13/2023]
Abstract
Brownian diffusion of spherical nanoparticles is usually exploited to ascertain the rheological properties of complex media. However, the behavior of the tracer particles is affected by a number of phenomena linked to the interplay between the dynamics of the particles and polymer coils. For this reason, the characteristic lengths of the dispersed entities, depletion phenomena, and the presence of sticking conditions have been observed to affect the translational diffusion of the probes. On the other hand, the retardation effect of the host fluid on the rotational diffusion of nonspherical particles is less understood. We explore the possibility of studying this phenomenon by analyzing the electro-orientation of the particles in different scenarios in which we vary the ratio between the particle and polymer characteristic size, and the geometry of the particles, including both elongated and oblate shapes. We find that the Stokes-Einstein relation only applies if the radius of gyration of the polymer is much shorter than the particle size and when some repulsive interaction between both is present.
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Affiliation(s)
- Sergio Martín-Martín
- Department
of Applied Physics, School of Sciences, University of Granada, 18071Granada, Spain
| | | | - Antonio Rubio-Andrés
- Department
of Applied Physics, School of Sciences, University of Granada, 18071Granada, Spain
| | - Ana B. Bonhome-Espinosa
- Department
of Applied Physics, School of Sciences, University of Granada, 18071Granada, Spain
| | - Ángel V. Delgado
- Department
of Applied Physics, School of Sciences, University of Granada, 18071Granada, Spain
| | - María L. Jiménez
- Department
of Applied Physics, School of Sciences, University of Granada, 18071Granada, Spain,
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Hendley RS, Torres-Díaz I, Bevan MA. Anisotropic colloidal interactions & assembly in AC electric fields. SOFT MATTER 2021; 17:9066-9077. [PMID: 34617557 DOI: 10.1039/d1sm01227d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We match experimental and simulated configurations of anisotropic epoxy colloidal particles in high frequency AC electric fields by identifying analytical potentials for dipole-field and dipole-dipole interactions. We report an inverse Monte Carlo simulation algorithm to determine optimal fits of analytical potentials by matching simulated and experimental distribution functions for non-uniform liquid, liquid crystal, and crystal microstructures in varying amplitude electric fields. Two potentials that include accurate particle volume and dimensions along with a concentration dependent prefactor quantitatively capture experimental observations. At low concentrations, an effective ellipsoidal point dipole potential works well, whereas a novel stretched point dipole potential is found to be suitable at all concentrations, field amplitudes, and degrees of ordering. The simplicity, accuracy, and adjustability of the stretched point dipole potential suggest it can be applied to model field mediated microstructures and assembly of systematically varying anisotropic particle shapes.
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Affiliation(s)
- Rachel S Hendley
- Chemical & Biomolecular Engr., Johns Hopkins Univ., Baltimore, MD 21218, USA.
| | - Isaac Torres-Díaz
- Chemical & Biomolecular Engr., Johns Hopkins Univ., Baltimore, MD 21218, USA.
| | - Michael A Bevan
- Chemical & Biomolecular Engr., Johns Hopkins Univ., Baltimore, MD 21218, USA.
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Wang J, Zhao X, Liu Y, Qian L, Yao L, Xing X, Mo G, Cai Q, Chen Z, Wu Z. Small-angle X-ray scattering study on the orientation of suspended sodium titanate nanofiber induced by applied electric field. RADIATION DETECTION TECHNOLOGY AND METHODS 2019. [DOI: 10.1007/s41605-019-0118-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cuetos A, Mirzad Rafael E, Corbett D, Patti A. Biaxial nematics of hard cuboids in an external field. SOFT MATTER 2019; 15:1922-1926. [PMID: 30756112 DOI: 10.1039/c8sm02283f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
By computer simulation, we model the phase behaviour of colloidal suspensions of board-like particles under the effect of an external field and assess the still disputed occurrence of the biaxial nematic (NB) liquid crystal phase. The external field promotes the rearrangement of the initial isotropic (I) or uniaxial nematic (NU) phase and the formation of the NB phase. In particular, very weak field strengths are sufficient to spark a direct I-NB or NU-NB phase transition at the self-dual shape, where prolate and oblate particle geometries fuse into one. By contrast, forming the NB phase at any other geometry requires stronger fields and thus reduces the energy efficiency of the phase transformation. Our simulation results show that self-dual shaped board-like particles with moderate anisotropy are able to form NB liquid crystals under the effect of a surprisingly weak external stimulus and suggest a path to exploit low-energy uniaxial-to-biaxial order switching.
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Affiliation(s)
- Alejandro Cuetos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
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Klop KE, Dullens RPA, Lettinga MP, Egorov SA, Aarts DGAL. Capillary nematisation of colloidal rods in confinement. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1497210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Kira E. Klop
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Roel P. A. Dullens
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
| | - M. Paul Lettinga
- ICS-3, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Laboratory for Soft Matter and Biophysics, KU Leuven, Leuven, Belgium
| | - Sergei A. Egorov
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Dirk G. A. L. Aarts
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
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Electro-optic Kerr effect in the study of mixtures of oppositely charged colloids. The case of polymer-surfactant mixtures in aqueous solutions. Adv Colloid Interface Sci 2017; 247:234-257. [PMID: 28552423 DOI: 10.1016/j.cis.2017.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/04/2017] [Accepted: 05/14/2017] [Indexed: 11/20/2022]
Abstract
In this review I highlight a very sensitive experimental technique for the study of polymer-surfactant complexation: The electro-optic Kerr effect. This review does not intend to be exhaustive in covering the Kerr Effect nor polymer-surfactant systems, instead it aims to call attention to an experimental technique that, even if applied in a qualitative manner, could give very rich and unique information about the structures and aggregation processes occurring in mixtures of oppositely charged colloids. The usefulness of electric birefringence experiments in the study of such systems is illustrated by selected results from literature in hope of stimulating the realization of more birefringence experiments on similar systems. This review is mainly aimed at, but not restricted to, researchers working in polyelectrolyte-surfactant mixtures in aqueous solutions, Kerr effect is a powerful experimental tool that could be used in the study of many systems in diverse areas of colloidal physics.
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Pham AT, Zhuang Y, Detwiler P, Socolar JES, Charbonneau P, Yellen BB. Phase diagram and aggregation dynamics of a monolayer of paramagnetic colloids. Phys Rev E 2017; 95:052607. [PMID: 28618506 DOI: 10.1103/physreve.95.052607] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Indexed: 06/07/2023]
Abstract
We have developed a tunable colloidal system and a corresponding theoretical model for studying the phase behavior of particles assembling under the influence of long-range magnetic interactions. A monolayer of paramagnetic particles is subjected to a spatially uniform magnetic field with a static perpendicular component and a rapidly rotating in-plane component. The sign and strength of the interactions vary with the tilt angle θ of the rotating magnetic field. For a purely in-plane field, θ=90^{∘}, interactions are attractive and the experimental results agree well with both equilibrium and out-of-equilibrium predictions based on a two-body interaction model. For tilt angles 50^{∘}≲θ≲55^{∘}, the two-body interaction gives a short-range attractive and long-range repulsive interaction, which predicts the formation of equilibrium microphases. In experiments, however, a different type of assembly is observed. Inclusion of three-body (and higher-order) terms in the model does not resolve the discrepancy. We further characterize the anomalous regime by measuring the time-dependent cluster size distribution.
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Affiliation(s)
- An T Pham
- NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, North Carolina 27708, USA
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
| | - Yuan Zhuang
- NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, North Carolina 27708, USA
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Paige Detwiler
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Joshua E S Socolar
- NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, North Carolina 27708, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - Patrick Charbonneau
- NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, North Carolina 27708, USA
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - Benjamin B Yellen
- NSF Research Triangle Materials Research Science and Engineering Center, Duke University, Durham, North Carolina 27708, USA
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
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