Adsorption of linear polymers on polyethersulfone membranes: Contribution of divalent counterions on modifying of hydrophilic–lipophilic balance of polyelectrolyte chain

Viscous Fingering Induced by a pH-Sensitive Clock Reaction

A pH-changing clock chemical system, also known to induce changes in viscosity, is shown experimentally to induce a viscous fingering instability during the displacement of reactive solutions in a Hele-Shaw cell. Specifically, a low-viscosity solution of formaldehyde is displaced by a more viscous solution of sulfite and of a pH-sensitive poly(acrylic acid) polymer. The pH change triggered by the formaldehyde-sulfite clock reaction in the reactive contact zone between the two solutions affects the polymer and induces a local increase of the viscosity that destabilizes the displacement via a viscous fingering instability. The influence of changes in the chemical parameters on this fingering instability is analyzed using different techniques and the results are compared with numerical simulations.

Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction

Conformational changes of a PAA molecule linked to a pH-changing reaction can produce a temporal viscosity modulation.