Self-diffusion in dilute colloidal suspensions with attractive potential interactions

Abstract

The colloidal short-time self-diffusivity D(s)(s)(phi) is significantly retarded relative to hard sphere suspensions for the case of interparticle potential interactions induced by a nonadsorbing polymer. A comparison of diffusing wave spectroscopy measurements with direct calculations of D(s)(s)(phi) demonstrates that depletion effects on structure explain the observed retardation. We show that coexistence boundaries place unexpectedly severe constraints on the amount of D(s)(s)(phi) retardation possible for stable suspensions. The measured retardation is demonstrated to be an indicator of suspension metastability.

Collective diffusion in charge-stabilized suspensions: Concentration and salt effects

“…Recent studies on shorttime diffusion, where H͑q͒, D͑q͒, or D s have been determined by appropriately selected scattering experiments, comprise charge-stabilized colloidal spheres, [3][4][5][6][7][8] hard-spherelike suspensions, [9][10][11] aqueous solutions of charged globular proteins, 12 solutions of neutral and charged liposomes, 13 dispersions of soft core-shell particles 14 and of soft microgel spheres, 15 and suspensions of polystyrene spheres with depletion-induced attraction. 16 Experimental results 17 for the hydrodynamic function of highly charged colloidal spheres at low volume fractions ͑typically smaller than 0.05͒ are in excellent agreement with the theoretical predictions of Nägele 2 obtained using a pairwise-additivity approximation of HIs. In its simplest form, this theory accounts only for the leading far-field ͑i.e., Rotne-Prager͒ part of the hydrodynamic pair mobilities which dominates in very dilute systems kept at low salinity.…”

Effect of weak attractive interactions on flow behavior of highly concentrated crystalline suspensions

“…Their investigations revealed a faster induction of wall crystallization as well as a slowing down of precursor to bulk crystal conversion and suppression of bulk crystal growth at higher polymer concentration. This slowing down of bulk crystallization is related to a reduced mobility of colloids due to the added polymer [Zausch et al (2009);Seefeld and Solomon (2003); Pusey et al (1993)]. Accordingly, the size of crystals found at the channel inlet in our experiments decreased with increasing polymer concentration.…”

Spatially and temporally reconfigurable assembly of colloidal crystals

“…1 is not due to optical trapping and radiation pressure, because the particles are nearly refractive index matched with the solvent (Dn/n ¼ 0.002). The observed colloidal velocity is three orders of magnitude greater than what would be expected due to optical trapping and radiation pressure, as per a calculation using the Mie scattering theory 17,24 .…”