R. Espert et al., FORCES BETWEEN LIQUID INTERFACES IN THE PRESENCE OF POLYMER - CONCENTRATION, SOLVENT, AND MASS EFFECTS, Macromolecules, 31(20), 1998, pp. 7023-7029
We report surface force measurements; between emulsion droplets and fl
at air-water interfaces (foam films) in the presence of an aqueous sta
tistical copolymer solution (of poly(vinyl alcohol) and poly(vinyl ace
tate)) in the dilute regime. We observe a repulsive force that is expo
nentially decaying and that cannot be attributed to electrostatic doub
le-layer repulsion. The qualitative behavior of the repulsive force we
akly depends on the polymer concentration, while its range is a functi
on of the polymer average molecular weight that is varied from 10 000
to 155 000. The force is drastically affected when the temperature app
roaches the Theta point (going from gl,od to Theta conditions). We sho
w that the force range scales as the polymer coil radius of gyration.
These results are compared with theoretical predictions.