Mechanism of flow-induced biomolecular and colloidal aggregate breakup

Abstract

The drift-diffusion equation is first solved analytically for the dissociation rate and lifetime of a biomolecular or colloidal dimer bonded by realistic intermolecular potentials, under shear flow. Then we show using rigidity percolation concepts that the lifetime of a generic cluster formed under shear is controlled by the typical lifetime of a single bond in its interior. The latter, however, is also affected by collective stress transmission from other bonds in the aggregate, which we account for by introducing a semiempirical, analytical stress transmission efficiency 0 1 calibrated on several simulation data sets. We show that aggregate breakup is a thermally activated process in which the activation energy is controlled by the interplay between intermolecular forces and the shear drift. The collective contribution to the overall shear drift term is dominant for large enough fractal aggregates, while surface erosion prevails for small and compact aggregates. The crossover between the two regimes occurs when N 2, where both the number of particles in the cluster N and the stress transmission efficiency depend on the aggregate structure through the fractal dimension d f . The analytical framework for the aggregate breakup rate is in quantitative agreement with experiments and can be used in future studies in the population balance modeling of colloidal and protein aggregation.

Plasticity in colloidal gel strands

“…6b). These findings are in agreement with theoretical models based on Kramers theory for force-activated bond rupture, which predict a rupture probability that decreases exponentially with the interaction strength and a threshold force that, for a given strain rate, is proportional to the effective spring constant and thus to the attraction strength e. 4,37,43 From the elastic contribution to the force, we observe that the change in rest length induced by the deformation cycles does not depend on the attraction strength (Fig. 6c).…”

Fractal-like structures in colloid science

“…Fig. 3b) as recently clarified by Conchuir and Zaccone for DLVO potentials [66]. For larger clusters instead, it is not merely a question of breakage energy required but also of number of neighboring particles.…”

Effect of Hydrodynamic Interactions on the Lifetime of Colloidal Bonds

“…[27][28][29] The single-bond lifetime, for which we provided a theory here, is also the starting point for a bottom-up description of the yielding of colloidal gels and glasses, and of the phenomenon of colloidal aggregate breakup under flow, where the escape is assisted by both diffusion and stress-transmission. [30][31][32][33][34] In a different context, the lifetime of colloidal bond may affect the kinetic evolution of clusters in colloidal nucleation, where a huge discrepancy persists between the nucleation rate from experiments (where HI are important)…”