Diffusiophoresis of latex particles in electrolyte gradients

Ebel, James P.; Anderson, John L.; Prieve, Dennis C.

doi:10.1021/la00080a024

Cited by 172 publications

(184 citation statements)

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“…The enhanced colloid transport is not surprising as it has already been reported in a number of studies (7,16,17). However, we have also observed that the density profile of the leading colloids is nonuniform in the lateral direction, and the colloidal particles tend to concentrate as they transport along the channel ( Fig.…”

supporting

confidence: 85%

“…A remarkable fact is that even when κa ≈ 100, unlike electrophoretic mobility (20), the predicted diffusiophoretic mobility deviates noticeably from Γ p ðκa → ∞Þ (10). When κa ≈ 10, which is a general condition for common diffusiophoresis experiments (7,12,16,17), the diffusiophoretic mobility is predicted to be almost an order of magnitude lower, depending on ζ p (10). Our experimental conditions are in a similar range, κa ≈ 2 − 40 [κ −1 = 13.6 nm when c = ðc i + c o Þ=2 ≈ 1 mM], indicating that size effects can be significant.…”

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confidence: 99%

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Size-dependent control of colloid transport via solute gradients in dead-end channels

Shin

Sabass

et al. 2015

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

220

261

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Transport of colloids in dead-end channels is involved in widespread applications including drug delivery and underground oil and gas recovery. In such geometries, Brownian motion may be considered as the sole mechanism that enables transport of colloidal particles into or out of the channels, but it is, unfortunately, an extremely inefficient transport mechanism for microscale particles. Here, we explore the possibility of diffusiophoresis as a means to control the colloid transport in dead-end channels by introducing a solute gradient. We demonstrate that the transport of colloidal particles into the dead-end channels can be either enhanced or completely prevented via diffusiophoresis. In addition, we show that size-dependent diffusiophoretic transport of particles can be achieved by considering a finite Debye layer thickness effect, which is commonly ignored. A combination of diffusiophoresis and Brownian motion leads to a strong size-dependent focusing effect such that the larger particles tend to concentrate more and reside deeper in the channel. Our findings have implications for all manners of controlled release processes, especially for site-specific delivery systems where localized targeting of particles with minimal dispersion to the nontarget area is essential.T he ability of a particle to migrate along a local solute concentration gradient, which is referred to as diffusiophoresis, has been exploited to direct transport in a variety of systems, e.g., artificial swimmers (1, 2) and collective behaviors of active colloids (3, 4). One physical mechanism for diffusiophoresis originates from surface-solute interactions, where the solute gradient sets up an osmotic pressure gradient within a narrow interaction region. This gradient leads to fluid flow along the surface of a particle, in which case propulsion occurs in the opposite direction and is referred to as chemiphoresis (5, 6). In addition, differences in diffusivities between anions and cations lead to spontaneous electrophoresis of a particle, giving an additional propulsion mechanism. A particular feature of diffusiophoresis is that the diffusiophoretic mobility, or the phoretic velocity, of a particle is independent of its size, as long as the thickness of the interaction region, e.g., the Debye screening layer when the interaction is electrostatic, is much thinner than the size of the particle (6). This feature allows the utilization of diffusiophoresis for enhancing transport of microscale particles, leading to orders of magnitude higher transport rates compared with pure diffusion (7). However, this size independence could also be a source of frustration because it precludes useful effects such as sorting or controlling transport by particle size.We anticipate that size-independent particle mobility breaks down when the thickness of the surface-solute interaction region becomes comparable to the size of the particle. Already more than a century ago this feature has been well appreciated in the field of electrokinetics as the Hückel limit (8) w...

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supporting

confidence: 85%

mentioning

confidence: 99%

Size-dependent control of colloid transport via solute gradients in dead-end channels

Shin

Sabass

et al. 2015

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

220

261

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“…We point to two potential origins of the light-induced chemistry. The light could catalyse a reaction of dissolved species, such as residual water, oxygen, or surfactants such as TBAB at the ITO substrate; these redox reactions would drive a current that would induce an electric field; or, the light-induced ionization of dissolved species, such as TBAB, could create a concentration gradient within the solution, spontaneously setting up an electric field and thereby generating electrodiffusiophoresis 33 . Both mechanisms are consistent with the observation that the photo-induced motion requires illumination of a semiconducting or metallic substrate that is in direct contact with the colloidal solution.…”

Section: Discussionmentioning

confidence: 99%

Spatially and temporally reconfigurable assembly of colloidal crystals

2014

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The self-assembly of colloidal crystals is important to the production of materials with functional optical, mechanical and conductive properties. Yet, self-assembly methods are limited by their slow kinetics and lack of structural control in space and time. Refinements such as templating and directed assembly partially address the problem, albeit by introducing fixed surface features such as templates or electrodes. A template-free method to reconfigure colloidal crystals simultaneously in three-dimensional space and time would better align work in colloidal assembly with materials applications. Here, we report a photo-induced assembly method that yields regions either filled with colloidal crystals or completely devoid of colloids. The origin of the effect is found to be electrophoresis of colloids generated by photochemistry at an indium tin oxide-coated substrate. Simple optical manipulations are applied to reconfigure these assembly and depletion regions. Thus, the method represents a new kind of template-free, reconfigurable three-dimensional photolithography.

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“…The generality of these findings provides a conceptual picture for understanding, predicting, or designing diffusiophoretic systems. Diffusiophoresis (DP) occurs when colloidal particles are driven into motion by solute concentration gradients [1][2][3]. In recent years, interest in DP has surged, particularly in new contexts such as polymer coating [4], membrane fouling [5,6], enhanced transport of particles into or out of dead-end pores [7,8], self-propelled particles [9,10], and the design of long-range "soluto-inertial" interactions in suspensions [11].…”

Section: Diffusiophoretic Focusing Of Suspended Colloidsmentioning

confidence: 99%