Scattering from small colloidal particles in a semidilute polymer solution

Sear, RP

doi:10.1007/s100510050188

Cited by 20 publications

(27 citation statements)

References 22 publications

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“…Our g pc (r) results are in qualitative agreement with recent scaling-based analysis in the ''protein limit'' for semidilute polymer solutions. 18 The attractive depletion effect is manifested in g cc (rϭ2R)Ͼ1, and g cc (r) decays towards unity monotonically on the length scale.…”

Section: ͑19͒mentioning

confidence: 99%

“…Examples of such systems include suspensions of silica or latex particles [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] as well as of globular protein molecules. [17][18][19][20] The stability of such dispersions is a strong function of the concentration and molecular weight of added polymer. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Predicting the phase behavior and stability with respect to flocculation of the spherical particles requires understanding the interplay between complex interactions governing the structure and thermodynamics of a threecomponent mixture.…”

Section: Introductionmentioning

confidence: 99%

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Microscopic theory of polymer-mediated interactions between spherical particles

Chatterjee¹,

Schweizer²

1998

The Journal of Chemical Physics

128

112

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We develop an analytic integral equation theory for treating polymer-induced effects on the structure and thermodynamics of dilute suspensions of hard spheres. Results are presented for the potential of mean force, free energy of insertion per particle into a polymer solution, and the second virial coefficient between spheres. The theory makes predictions for all size ratios between the spheres and the polymer coil dimension. Based on the Percus-Yevick ͑PY͒ closure, the attractive polymer-induced depletion interaction is predicted to be too weak under athermal conditions to induce a negative value for the second virial coefficient, B 2 cc , between spheres in the colloidal limit when the spheres are much larger than the coil size. A nonmonotonic dependence of the second virial coefficient on polymer concentration occurs for small enough particles, with the largest polymer-mediated attractions and most negative B 2 cc occurring near the dilute-semidilute crossover concentration. Predictions for the polymer-mediated force between spheres are compared to the results of computer simulations and scaling theory.

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Section: ͑19͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microscopic theory of polymer-mediated interactions between spherical particles

Chatterjee¹,

Schweizer²

1998

The Journal of Chemical Physics

128

112

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“…The second virial coefficient, which can be measured by light scattering, is of particular interest, since in protein suspensions its value appears to be correlated with the success of protein crystallization. 18 We make contact with the results of Chatterjee and Schweizer, 8 based on an integral equation approach for arbitrary overlap and with the results of Sear 19 In Sec. V the overlap-dependence of the polymerinduced interaction of a particle with a wall is considered.…”

Section: ͑15͒mentioning

confidence: 99%

“…Equations ͑2.2͒ and ͑2.3͒ generalize Eq. ͑8͒ of Sear,19 valid for the semidilute limit, to arbitrary overlap and provide the missing prefactor in this relation. If the distance r AB between the two particles is much smaller than R g and , the quantity K in Eq.…”

Section: Potential Of Mean Force Between Two Particlesmentioning

confidence: 99%

Small mesoscopic particles in dilute and semidilute solutions of nonadsorbing polymers

Eisenriegler

2000

The Journal of Chemical Physics

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Polymer-induced interactions between two small mesoscopic particles of radius R and between a particle and a wall are investigated for dilute or semidilute embedding solutions of long flexible nonadsorbing polymer chains with radius of gyration R g . Asymptotically exact predictions are obtained using a ''small radius expansion,'' to express the interactions in terms of properties of the polymer solution without particles. The nonmonotonic dependence of the second virial coefficient B 2 CC of a dilute suspension of particles on the interchain overlap is discussed in detail. The magnitude of the minimum of B 2 CC /R 3 increases as a power law in R g /R. The exponent and amplitude are quite different from the earlier prediction of an integral-equation approach. For dilute polymers in two dimensions outside two circular disks in contact, exact results are given for the monomer-density depletion profile, the pressure variation along the perimeter of, and the polymer-induced force between the two disks.

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“…where l p is the Kuhn-segment length, d the dimension of space, and the latter number density c [29,54,56]. Therefore, on a per-coil basis the free-energy increase is of order N , which requires the whole chain to rearrange around the particle.…”

Section: Dilute Particlesmentioning

confidence: 99%

Structure of colloid-polymer suspensions

Fuchs

Schweizer

2002

J. Phys.: Condens. Matter

208

274

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We discuss structural correlations in mixtures of free polymer and colloidal particles on the basis of a microscopic, two-component liquid-state integral equation theory. Whereas in the case of polymers much smaller than the spherical particles the relevant polymer degree of freedom is the centre of mass, for polymers larger than the (nano-) particles, conformational rearrangements need to be considered. They have the important consequence that the polymer depletion layer exhibits two widely different length scales, one of the order of the particle radius, the other of the order of the polymer radius or the polymerdensity screening length in dilute or semidilute concentrations, respectively. Because we find a spinodal instability (mostly) below the overlap concentration, the latter length is (mostly) set by the radius of gyration. As a consequence of the structure of the depletion layer, the particle-particle correlations depend on both length scales for large polymers. Because of the high local compressibility of large polymers, the local depletion layer is a strong function of particle density, but a weak function of polymer concentration. The amplitude of the long-ranged tail of the depletion layer also depends asymptotically only on the colloid concentration, while the range increases upon approaching the (meanfield) spinodal. The colloid correlations may be understood as characteristic for particles with a short-ranged potential when small polymers are added, and as characteristic for particles with a long-ranged, van der Waals-like attraction when the added free polymer coils are much larger. Small polymers fill the voids between the particles rather homogeneously, exhibiting correlations inside the mesh (which gets squeezed by the colloids) and Porod-like correlations for larger distances. The structure factor of large polymers, however, exhibits no ramified mesh and becomes a Lorentzian characterized by the mixture correlation length, which diverges at the spinodal.

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Scattering from small colloidal particles in a semidilute polymer solution

Cited by 20 publications

References 22 publications

Microscopic theory of polymer-mediated interactions between spherical particles

Microscopic theory of polymer-mediated interactions between spherical particles

Small mesoscopic particles in dilute and semidilute solutions of nonadsorbing polymers

Structure of colloid-polymer suspensions

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