Static and dynamic surface tension of dilute polyelectrolyte solutions

The surface tension of aqueous solutions of Polymer JR400, the chloride sal t of a trimethylammonium derivative of hydroxyethyl cellulose, has been mea sured as a function of polymer concentration. Axisymmetric drop shape analy sis profile has been employed to record the dynamic surface tension respons e of the solutions to a sawtooth-shaped variation in the surface area. Dilu te solutions of the polymer (concentration < 0.05 wt%) exhibited an elevati on of the surface tension of water, from 71.9 to 72.7 mJ m(-2) (23 degrees C) under both static and dynamic conditions. Under the latter, elevations o f as much as 3 mJ m-2 were observed during the surface contraction cycle. S olutions of concentrations higher than 0.05 wt% recovered the more conventi onal behavior of water surface tension depression and, in the dynamic measu rement mode, decreases in the surface tension during the contraction cycle. (C) 1999 Elsevier Science B.V. All rights reserved.