A pancake-to-brush transition in polymer adsorption

(Received 26 November 1990, accepted in final form 26 July 1991)

Abstract
We provide the first experimental evidence for a transition from a "pancake" to a "brush" configuration for end-adsorbing polymers at the solution-solid interface. This transition, predicted earlier by Alexander, is a consequence of the competition between adsorptions by the backbone and the end-groups. It occurs when polymer pancakes start to overlap each other. The competition then drives some backbones into solution to form brushes. The transition region varies with molecular weight but does not vary with the end-group's adsorption strength. The thickness of the polymer layer, however, increases with the increasing end-group's adsorption strength.