Electrophoresis of concentrated colloidal dispersions in low-polar solvents

Vissers, Teun; Imhof, Arnout; Carrique, F.; Delgado, A.V.; Blaaderen, Alfons van

doi:10.1016/j.jcis.2011.04.113

Cited by 35 publications

(70 citation statements)

References 62 publications

(85 reference statements)

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“…Most techniques measure the motion of single particles. 15,17,18,23 Several make use of optical tweezers to confine the particles when they are driven by an electric field. 13,17,23 Position determination at the single-particle level is done either using a photoquadrant detection scheme or by image processing.…”

Section: Introductionmentioning

confidence: 99%

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Charging of Poly(methyl methacrylate) (PMMA) Colloids in Cyclohexyl Bromide: Locking, Size Dependence, and Particle Mixtures

Linden

Stiefelhagen²,

Heessels-Gürboğa³

et al. 2014

Langmuir

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We studied suspensions of sterically stabilized poly(methyl methacrylate) (PMMA) particles in the solvent cyclohexyl bromide (CHB; εr = 7.92). We performed microelectrophoresis measurements on suspensions containing a single particle species and on binary mixtures, using confocal microscopy to measure the velocity profiles of the particles. We measured the charge of so-called locked PMMA particles, for which the steric stabilizer, a comb-graft stabilizer of poly(12-hydroxystearic acid) (PHSA) grafted on a backbone of PMMA, was covalently bonded to the particle, and for unlocked particles, for which the stabilizer was adsorbed to the surface of the particle. We observed that locked particles had a significantly higher charge than unlocked particles. We found that the charge increase upon locking was due to chemical coupling of 2-(dimethylamino)ethanol to the PMMA particles, which was used as a catalyst for the locking reaction. For particles of different size we obtained the surface potential and charge from the electrophoretic mobility of the particles. For locked particles we found that the relatively high surface potential (∼ +5.1 kBT/e or +130 mV) was roughly constant for all particle diameters we investigated (1.2 μm < σ < 4.4 μm), and that the particle charge was proportional to the square of the diameter.

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Section: Introductionmentioning

confidence: 99%

“…15 Of course, for more concentrated systems it is harder to convert a measured mobility to a surface charge or potential than for dilute systems. The approach taken in this paper is the same as in earlier work by our group, in which a Poisson−Boltzmann cell model was used to obtain these quantities.…”

Section: Introductionmentioning

confidence: 99%

Charging of Poly(methyl methacrylate) (PMMA) Colloids in Cyclohexyl Bromide: Locking, Size Dependence, and Particle Mixtures

Linden

Stiefelhagen²,

Heessels-Gürboğa³

et al. 2014

Langmuir

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“…9,[37][38][39][40] The interactions in these HSY systems are therefore more accurately described by constantpotential boundary conditions than constant-charge boundary conditions. 38,39,41 Only recently, phase diagrams for HSY systems were calculated within the constant-potential model.…”

Section: Introductionmentioning

confidence: 99%

Effect of size polydispersity on the crystal-fluid and crystal-glass transition in hard-core repulsive Yukawa systems

Linden¹,

Blaaderen²,

Dijkstra³

2013

The Journal of Chemical Physics

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We investigated the effect of size polydispersity on the crystal-fluid transition in hard-core repulsive Yukawa systems by means of Monte Carlo simulations for several state points in the Yukawa parameter space. Size polydispersity was introduced in the system only with respect to the hard particle cores; particles with different diameters had the same surface potential ψ 0 , but the charge per particle was not varied with packing fraction or distance. We observed a shift to higher packing fraction of the crystal-fluid transition of bulk crystals with a fixed log-normal size distribution upon increasing the polydispersity, which was more pronounced for weakly charged particles (ψ 0 ≈ 23 mV) compared to more highly charged particles (ψ 0 ≈ 46 mV), and also more pronounced for larger Debye screening length. At high polydispersities (≥0.13) parts of the more highly charged systems that were initially crystalline became amorphous. The amorphous parts had a higher polydispersity than the crystalline parts, indicating the presence of a terminal polydispersity beyond which the homogeneous crystal phase was no longer stable.

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“…From the electrophoretic mobilities in the mixed concentrated suspension G ¼ À3:6 Â 10 À11 m 2 =Vs and R ¼ 2:9 Â 10 À11 m 2 =Vs and the concentration of TBAB salt (ca. 2 M), we estimate the particle charges to be Z G e % À102e for the green and Z R e % 78e for the red particles (supplemental in [17], [21]). The screening length À1 % 550 nm.…”

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Band Formation in Mixtures of Oppositely Charged Colloids Driven by an ac Electric Field

2011

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We present experiments on pattern formation in a Brownian system of oppositely charged colloids driven by an ac electric field. Using confocal laser scanning microscopy we observe complete segregation of the two particle species into bands perpendicular to a field of sufficient strength when the frequency is in a well-defined range. Because of its Brownian nature the system spontaneously returns to the equilibrium mixture after the field is turned off. We show that band formation is linked to the time scale associated with collisions between particles moving in opposite directions. DOI: 10.1103/PhysRevLett.106.228303 PACS numbers: 82.70.Dd, 47.54.-r, 89.75.Kd Pattern formation is found on many different length scales and as a consequence is studied in molecular systems [1,2], geology [3], the animal kingdom [4,5], granular systems [6], and colloids [7]. Granular and colloidal systems are especially interesting since they can be studied in real space on the single-particle level due to their slow dynamics and relatively large size compared to atoms and molecules [8,9]. A visually compelling case of pattern formation is found in binary granular systems containing two different particles species that segregate when the mixture is subjected to mechanical agitation [10][11][12]. Recently, it was shown that periodically sheared granular suspensions [13] can undergo an out-of-equilibrium phasetransition from a dynamic fluctuating state into a quiescent ''absorbing state'', which can also be found in epidemics and on the surface of certain heterogeneous catalysts [14].Computer simulations have recently identified binary mixtures of colloidal particles driven in opposite directions by an external field as an interesting test bed for pattern formation in complex systems [15,16]. Such colloidal systems are all the more interesting because they are thermal systems: Brownian motion allows any induced nonequilibrium state to spontaneously relax back to the equilibrium mixture, and presents pattern formation as a competition between field-induced ordering and thermal disordering. Such a binary colloidal system is hard to realize in experiment, however, because of strict requirements placed on a sufficiently strong interaction with the driving field and the thermodynamic stability of the mixture. Nevertheless, we recently succeeded in developing a system of oppositely charged colloids that can be studied in 3D real space when exposed to an external electric field. We performed a combined experimental and Brownian dynamics simulation study, which showed that as a result of collisions between particles moving in opposite directions, the different particle species segregate into lanes parallel to the field [17]. We also demonstrated that the fraction of particles in a lanelike environment increased monotonically with field strength. Once particles were in a lane, fluctuations perpendicular to the field axis decreased and the electrophoretic mobility increased with respect to particles not in a lane.Here, we employ this binary ...

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Electrophoresis of concentrated colloidal dispersions in low-polar solvents

Cited by 35 publications

References 62 publications

Charging of Poly(methyl methacrylate) (PMMA) Colloids in Cyclohexyl Bromide: Locking, Size Dependence, and Particle Mixtures

Charging of Poly(methyl methacrylate) (PMMA) Colloids in Cyclohexyl Bromide: Locking, Size Dependence, and Particle Mixtures

Effect of size polydispersity on the crystal-fluid and crystal-glass transition in hard-core repulsive Yukawa systems

Band Formation in Mixtures of Oppositely Charged Colloids Driven by an ac Electric Field

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