Free-Standing Black Films of Polymers: A Model of Charged Brushes in Interaction

Abstract
Free-standing black films drawn from a diblock copolymer aqueous solution were studied by x-ray reflectivity. Because of the hydrophilic part of the copolymer which is a highly charged polyelectrolyte (NaPSS), such films behave as two opposing charged brushes. Above a determined threshold the thickness of the double brush decreases slowly as electrolyte is added. These results are in good agreement with recent mean-field theories.