Depletion flocculation induced by synergistic effects of nanoparticles and polymers.

The depletion flocculation of stable suspensions of charged microparticles (1.2 μm diameter polystyrene) by mixtures of silica nanoparticles (7 nm) and poly(acrylic) acid (PAA, Mn = 24 500) was studied. The experiments revealed a very clear critical flocculation concentration of PAA that was lowered by the addition of the silica nanoparticles.

Synergistic effects of nanoparticles and polymers on depletion and structural interactions.

An experimental study was performed to investigate the synergistic effects of two different solution components on the depletion and structural forces between colloidal particles. Using silica nanoparticles and anionic poly(acrylic acid) polymer, it was found that the depletion and structural forces measured between a 30 μm diameter silica sphere and a flat silica plate (obtained using colloidal probe atomic force microscopy) were substantially greater than the sum of the forces obtained in systems containing only nanoparticles and only polymer. This result arises because the anionic polymer chains adsorb to the nanoparticles, creating a complex that is over twice as large as either component.

Interaction potentials between two colloidal particles surrounded by an extremely bidisperse particle suspension.

The results of a computational study predicting the equilibrium forces between two colloidal particles (microparticles) in a solution containing both submicroparticles and nanoparticles (e.g., one and two orders-of-magnitude smaller than the microparticles, respectively) are presented.