Warner Kuhnd̊. (1899‐1963)

Kuhn, Hans

doi:10.1002/hlca.19640470302

Cited by 75 publications

(107 citation statements)

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“…The viscosities for LiCl concentrations of 10 and 100 mM are practically equal and, for volume fractions below the rod overlap value (f* % 0.008), close to the theoretical prediction of order f 2 for hard rods. 61,62 Thus, rheology suggests hard-rod-like behavior for LiCl concentrations q10 mM. In contrast, the rotational diffusion results show no evidence of enhanced screening of electrostatic repulsions at 10 mM LiCl as compared to 0 mM LiCl.…”

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confidence: 84%

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

et al. 2002

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According to the Stokes-Einstein-Debye (SED) relation, the rotational diffusion coefficient of a colloidal tracer sphere scales with the inverse of the solvent viscosity. Here we investigate the generalization of the SED relation to tracer diffusion in suspensions of neutral and charged colloidal host spheres. Rotational diffusion coefficients are measured with dynamic light scattering and phosphorescence spectroscopy, and calculated including two-and three-particle hydrodynamic interactions. We find that rotational tracer diffusion is always faster than predicted by the SED relation, except for large tracer/host size ratios l. In the case of neutral particles this observation is rationalized by introducing an apparent l-dependent slip boundary coefficient. For charged spheres at low ionic strength, large deviations from SED scaling are found due to the strongly hindered host sphere dynamics. Finally, we present some first experiments on tracer sphere diffusion in suspensions of host rods, showing that hydrodynamic hindrance by rods is much stronger than by spheres. We conclude by pointing to some interesting unresolved issues for future research. I IntroductionThe rotational diffusion coefficient of a single colloidal sphere with radius a T suspended in a solvent with shear viscosity Z 0 is given by the familiar Stokes-Einstein-Debye (SED) relationwith k B T the thermal energy and f r 0 the Stokesian friction factor. Eqn. (1) assumes that the particle is large enough for the solvent to behave as a structureless continuum with vanishing response time. Moreover, stick boundary conditions are assumed, i.e. the velocity of the fluid on the tracer surface equals that of the tracer. Eqn. (1) holds quantitatively not only for colloidal particles but,

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confidence: 84%

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

et al. 2002

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“…As the diffusion coefficient D is related to (L 2 ) by29 (18) The concentration dependence of the diffusion coefficient of a segment can be expressed by (19) where D0 is the diffusion coefficient of the segment when placed separately in the fluid. By using the Einstein relation 23…”

Section: Diffusion Coefficient Of Segmentsmentioning

confidence: 99%

Fast Reaction and Micro-Brownian Motion of Flexible Polymer Molecules in Solution

Horie

Mita

Kambe

1973

Polym J

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ABSTRACT:The rate of fast reactions in solution between two flexible polymer molecules with active chain ends is studied in relation to the theory of micro-Brownian motion of polymer segments in solution. The comparison of relaxation times for five types of molecular and segmental motions indicates that the translational diffusion of chain end segments is the rate-determining step. The segmental diffusion coefficient depending on the position based on the model of random flights with correlations is related to the rate constant by using the Smoluchowski equation and the potential energy function for intermolecular interaction. The rate constant can be expressed as a product of three components without any arbitrary parameters, (l;,o, T) where A(o:) represets the effect of solution properties, B(n) the effect of molecular weight, and C(l;,0, T) the effect of frictional properties of the segment. This equation predicts that the rate constant is inversely proportional to solvent viscosity, decreases with increassing molecular weight to some extent, and is markedly affected by the excluded volume effect and chain flexibility. Close agreement is found between the calculated rate constants and those experimentally obtained.KEY WORDS

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“…The suitability of a clay suspension as a simple model system for plates is nevertheless severely limited by the polydispersity, swelling, and long-range interactions of the clay platelets (4,5). The existing lack of experiments on a hard (i.e., short-range repulsive) platelet model system is accompanied by a scarcity of theoretical work and simulations addressing the physical properties of platelike particles (6,7).…”

Section: Introductionmentioning

confidence: 99%

Rheology of Dilute Suspensions of Hard Platelike Colloids

Kooij

Boek

Philipse

2001

Journal of Colloid and Interface Science

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Warner Kuhnd̊. (1899‐1963)

Abstract: Socidtd suisse de chimie, Bale -Societ8 svizzera di chimica, Basilea Nachdruck verboten. -Tuus droits r6servBs. -Printed by Birkhauser AG., Basel, Switzcrland Erscheint 9mal jahrlich -Parait 9fois par an

Cited by 75 publications

References 0 publications

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

Fast Reaction and Micro-Brownian Motion of Flexible Polymer Molecules in Solution

Rheology of Dilute Suspensions of Hard Platelike Colloids

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