Adsorption of neutral polymers: loops and tails

Equilibrium layers obtained by adsorption from polymer solution exhibit a d ouble-layer structure: the inner layer is built up mainly by loops whereas the outer layer is built up mainly by tails. In the asymptotic limit of lon g chains (N --> infinity) the loop layer extends over a distance z* similar to N1(d-1) (d being the dimension of space) for dilute bulk solution. The thickness of the tail-layer is of the order of the coil size lambda similar to N-v, and thus qualitatively larger. For increasing bulk concentration, the loops grow progressively and the two length scales merge at phi (2) sim ilar to N-(dv-1)/(2v(d-1)-1). We discuss a few consequences of the tail sta tistics on polymer layer interaction, exchange kinetics and polymer-colloid mixtures. A few related experiments are mentioned. (C) 2000 Academie des s ciences/Editions scientifiques et medicales Elsevier SAS.