The microstructure of polydisperse, charged colloidal suspensions by light and neutron scattering

Wagner, Norman J.; Krause, R.; Rennie, Adrian R.; D’Aguanno, Bruno; Goodwin, Jim W.

doi:10.1063/1.461450

Cited by 72 publications

(61 citation statements)

References 40 publications

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“…Equations [8] and [9] together are consistent with the linearized Poisson-Boltzmann theory, as the resulting Debye length is equal to that derived by Russel and Benzing (47). Note that ka is dependent on both the colloid charge neutrality and excluded volume effect implicit in Eqs.…”

Section: Torsional Resonatorsupporting

confidence: 74%

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Colloidal Charge Determination in Concentrated Liquid Dispersions Using Torsional Resonance Oscillation

Bergenholtz

Willenbacher

Wagner

et al. 1998

Journal of Colloid and Interface Science

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Section: Torsional Resonatorsupporting

confidence: 74%

“…/ n salt , [9] where n particles and n salt are the number concentrations of colloidal particles in the dispersion and of the salt in the dialysis bath. Equations [8] and [9] together are consistent with the linearized Poisson-Boltzmann theory, as the resulting Debye length is equal to that derived by Russel and Benzing (47).…”

Section: Torsional Resonatormentioning

confidence: 99%

Colloidal Charge Determination in Concentrated Liquid Dispersions Using Torsional Resonance Oscillation

Bergenholtz

Willenbacher

Wagner

et al. 1998

Journal of Colloid and Interface Science

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“…The rise of the peak height S(q max ) as ϕ increases is in good agreement with earlier light scattering results by Wagner et al [14] on smaller particles. At higher volume fractions between about 0.3% and 0.5%, however, the structure factor peak drops significantly to what appears to be a minimum (see fig.…”

supporting

confidence: 92%

Reappearance of structure in colloidal suspensions

Rojas¹,

Urban²,

Schurtenberger³

et al. 2002

Europhys. Lett.

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Abstract. -Static structure factors S(q) of deionized aqueous suspensions of charged polystyrene particles with similar radii but strongly differing bare charges have been measured for volume fractions 3.5 × 10 −4 ≤ ϕ ≤ 1.55 × 10 −2 , using a cross-correlation light scattering technique which allows for the extraction of single scattered light from highly turbid samples. Measurement of absolute intensities allowed to determine unambiguously normalized values of S(q). With decreasing volume fraction, the amplitude of the first peak of S(q) reflecting the order of the suspension does not monotonically decrease, but rather shows a distinct minimum at ϕ ∼ (5 − 8) × 10 −3 . This reappearance of structure is compared with theoretical predictions on the basis of a jellium model for the effective interparticle potential U eff (r).The forces governing the structure and phase behavior of suspensions of charged colloidal particles are of prime importance for many technological applications, such as ceramic processing, drug delivery or the stability control of paints. In the standard picture of Derjaguin, Landau, Verwey, and Overbeek (DLVO) [1], the electrostatic interaction between two charged colloidal particles in an electrolyte arises from the repulsion of the electric double layers that form due to the competition between configurational entropy of the small ions and their potential energy in the Coulomb field of the macroions with negative charge −Ze 0 , e 0 being the elementary charge. When the bare charge Z is large, a part of the surrounding counterions is strongly bound to the particle and thus reduces the bare charge to an effective chargeZ < Z which then governs the ion distribution at distances comparable to the Debye screening length κ −1 [2]. In contrast to the situation in simple liquids, however, the strength of the effective interparticle potential U eff (r) determined by the effective chargeZ and its range κ −1 does not only depend on the bare charge Z but also on the concentrations of co-and counterions and the particle volume fraction ϕ [3]. This density dependence of the effective potential is reflected by the fact that even at volume fractions as low as 10 −4 strongly charged particles show considerable order, as reflected by the strong first peak in the colloid-colloid structure factor S(q) measured in light scattering experiments from deionized suspensions [4,5]. When, at higher volume fractions, the number of counterions balancing the particle charge becomes larger than the number of excess salt ions, the screening will become dominated by the former,

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“…Here S D (k) is the decoupling approximation of S M (k) defined in Eq. [18]. The fact that S M (k ϭ 0; s (2) ) Ϸ 1 in Fig.…”

Section: Resultsmentioning

confidence: 88%

“…Major experimental tools for investigating the microstructure and diffusion of these systems are static and dynamic light scattering (SLS and DLS) (1-13) as well as small-angle X ray (14 -16) and neutron scattering experiments (17,18). Whereas the structural and dynamical properties of monodisperse colloids have been investigated in great detail, much less is known with regard to polydisperse suspensions and colloidal mixtures.…”

Section: Introductionmentioning

confidence: 99%