Thin double layer theory of the wide-frequency range dielectric dispersion of suspensions of non-conducting spherical particles including surface conductivity of the stagnant layer

Shilov, V. N.; Delgado, A.V.; González‐Caballero, F.; Grosse, Constantino

doi:10.1016/s0927-7757(01)00729-4

Cited by 108 publications

(127 citation statements)

References 18 publications

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“…Each sphere i with radius R i is located at the position r i . The polarizability of the sphere i can be expressed as α i = 4π« 0 «R 3 i K i , where K i is the polarization coefficient that can be calculated both analytically (42) and numerically (43). Two spheres representing the lobes on the same dimer are subject to the geometric constraint of fixed bond length L = r i − r j .…”

Section: Significancementioning

confidence: 99%

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Electric-field–induced assembly and propulsion of chiral colloidal clusters

Ma¹,

Wang²,

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

174

180

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Chiral molecules with opposite handedness exhibit distinct physical, chemical, or biological properties. They pose challenges as well as opportunities in understanding the phase behavior of soft matter, designing enantioselective catalysts, and manufacturing single-handed pharmaceuticals. Microscopic particles, arranged in a chiral configuration, could also exhibit unusual optical, electric, or magnetic responses. Here we report a simple method to assemble achiral building blocks, i.e., the asymmetric colloidal dimers, into a family of chiral clusters. Under alternating current electric fields, two to four lying dimers associate closely with a central standing dimer and form both right-and left-handed clusters on a conducting substrate. The cluster configuration is primarily determined by the induced dipolar interactions between constituent dimers. Our theoretical model reveals that in-plane dipolar repulsion between petals in the cluster favors the achiral configuration, whereas outof-plane attraction between the central dimer and surrounding petals favors a chiral arrangement. It is the competition between these two interactions that dictates the final configuration. The theoretical chirality phase diagram is found to be in excellent agreement with experimental observations. We further demonstrate that the broken symmetry in chiral clusters induces an unbalanced electrohydrodynamic flow surrounding them. As a result, they rotate in opposite directions according to their handedness. Both the assembly and propulsion mechanisms revealed here can be potentially applied to other types of asymmetric particles. Such kinds of chiral colloids will be useful for fabricating metamaterials, making model systems for both chiral molecules and active matter, or building propellers for microscale transport.hirality is a fundamental concept presented ubiquitously in the molecular world. For example, small molecules such as the amino acids, phospholipids, and sugars with specific handedness build many biomacromolecules whose chirality is essential to living organisms. Although the right-and left-handed molecules are identical in chemical composition, the catalytic activity (1), pharmacological impact (2, 3), biological recognition (4), and optical response (5) can be strikingly different. Extending the chiral structure to microscopic objects such as colloids has become increasingly desirable for several reasons. First, the chiral arrangement of colloidal particles can exhibit unusually strong optical, electric, and magnetic responses (6-10) that are not manifested either at the single-particle level or in achiral forms. Therefore, chiral clusters can be potentially used to build metamaterials (11-14) with exotic properties or sensors for detection of molecules. Second, chiral particles can be conveniently characterized by real-time optical microscopy. As the macroscopic analog of chiral molecules, they can be used to study fundamental questions related to the crystallization (15) or enantiomeric separation (16, 17) of a racemic...

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Section: Significancementioning

confidence: 99%

“…The polarization coefficient K i for particle i is calculated based on the low-frequency thin double-layer polarization theory (42). Fig.…”

Section: Significancementioning

confidence: 99%

Electric-field–induced assembly and propulsion of chiral colloidal clusters

Ma¹,

Wang²,

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

174

180

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“…Only numerical methods are available if this is the physical nature of the system under study. The reader is referred to [13][14][15][16]61,62,[67][68][69]. Figure 7 illustrates how important the effect of SLC on Re[ε * r (ω)] can be for the same conditions as in Fig.…”

Section: Dielectric Dispersion and ζ-Potential: Models Amentioning

confidence: 99%

“…Here, we focus on a simplified model [73] that allows the calculation of the volume-fraction dependence of both the low-frequency value of the real part of δε * r , and of the characteristic time τ α of the α-relaxation. The starting point is the assumption that L D , the length scale over which ionic diffusion takes place around the particle, can be averaged in the following way between the values of a very dilute (L D ≈ a) and a very concentrated (L D ≈ b -a; b is half the average distance between the centers of neighboring particles) dispersion: (67) or, in terms of the particle volume fraction (68) From these expressions, the simplified model allows us to obtain the dielectric increment at low frequency as follows. Let us call (69) the specific (i.e., per unit volume fraction) dielectric increment (for ω → 0).…”

Section: Nondilute Suspensions Of Nonconducting Spherical Particles Wmentioning

confidence: 99%

Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report)

Delgado

González‐Caballero

Hunter

et al. 2005

Pure and Applied Chemistry

520

398

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Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the Measurement and interpretation of electrokinetic phenomena (IUPAC Technical Report)Abstract: In this report, the status quo and recent progress in electrokinetics are reviewed. Practical rules are recommended for performing electrokinetic measurements and interpreting their results in terms of well-defined quantities, the most familiar being the ζ-potential or electrokinetic potential. This potential is a property of charged interfaces, and it should be independent of the technique used for its determination. However, often the ζ-potential is not the only property electrokinetically characterizing the electrical state of the interfacial region; the excess conductivity of the stagnant layer is an additional parameter. The requirement to obtain the ζ-potential is that electrokinetic theories be correctly used and applied within their range of validity. Basic theories and their application ranges are discussed. A thorough description of the main electrokinetic methods is given; special attention is paid to their ranges of applicability as well as to the validity of the underlying theoretical models. Electrokinetic consistency tests are proposed in order to assess the validity of the ζ-potentials obtained. The recommendations given in the report apply mainly to smooth and homogeneous solid particles and plugs in aqueous systems; some attention is paid to nonaqueous media and less ideal surfaces.

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“…This result thus also indicates that the aggregation happens when the volume fraction is bigger than 0.08. It is well known that relaxation amplitude, for example, ⌬ l ͑= l − m ͒, increases with increasing volume fraction, [35][36][37] but dielectric increment denotes the relaxation amplitude per unit volume and thereby is only decided by the induced dipole coefficient of a single particle. As the volume fraction increases, ion concentration in the bulk solution increases, then more counterions will reside in the stagnant layer of EDL and fewer counterions will be left in the diffuse layer.…”

Section: The Dispersion State Of Palladium Nanoparticle Chain In Tmentioning

confidence: 99%

Dielectric relaxation behavior of colloidal suspensions of palladium nanoparticle chains dispersed in PVP/EG solution

Chen

Zhao

Guo

et al. 2007

The Journal of Chemical Physics

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Phase separation in suspensions of colloids, polymers and nanoparticles: Role of solvent quality, physical mesh, and nonlocal entropic repulsion J. Chem. Phys. 118, 3880 (2003); 10.1063/1.1538600Reuse of AIP Publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. Dielectric measurements were carried out on colloidal suspensions of palladium nanoparticle chains dispersed in poly͑vinyl pyrrolidone͒/ethylene glycol ͑PVP/EG͒ solution with different particle volume fractions, and dielectric relaxation with relaxation time distribution and small relaxation amplitude was observed in the frequency range from 10 5 to 10 7 Hz. By means of the method based on logarithmic derivative of the dielectric constant and a numerical Kramers-Kronig transform method, two dielectric relaxations were confirmed and dielectric parameters were determined from the dielectric spectra. The dielectric parameters showed a strong dependence on the volume fraction of palladium nanoparticle chain. Through analyzing limiting conductivity at low frequency, the authors found the conductance percolation phenomenon of the suspensions, and the threshold volume fraction is about 0.18. It was concluded from analyzing the dielectric parameters that the high frequency dielectric relaxation results from interfacial polarization and the low frequency dielectric relaxation is a consequence of counterion polarization. They also found that the dispersion state of the palladium nanoparticle chain in PVP/EG solution is dependent on the particle volume fraction, and this may shed some light on a better application of this kind of materials.

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Thin double layer theory of the wide-frequency range dielectric dispersion of suspensions of non-conducting spherical particles including surface conductivity of the stagnant layer

Cited by 108 publications

References 18 publications

Electric-field–induced assembly and propulsion of chiral colloidal clusters

Electric-field–induced assembly and propulsion of chiral colloidal clusters

Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report)

Dielectric relaxation behavior of colloidal suspensions of palladium nanoparticle chains dispersed in PVP/EG solution

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