Organization of polymers at interfaces

We consider a set of ''simple'' polymer chains (linear, flexible, neutral, homogeneous) in the presence of a flat solid-liquid interface, where the surface is attractive and the chains adsorb reversibly. We show that the seating approach recently proposed by Aubouy, Guiselin, and Raphael (AGR) [Macromolecules 29, 7261 (1996)] to describe polymer layers theoretically is able to explain the major features of these interfaces: (i) The polymer chains build an interfacial layer with a well-defined structure. (ii) There is preferential adsorption of the longest chains in the dilute regime. (iii) There is preferential adsorption of the shortest chains in the concentrated regime. (iv) Ultrathin polymer films dewet surfaces that thick films would wet. We can thus (a) identify a single physical process responsible for all these different behaviors, namely: the competition between the entropy of the set of loops (which favors the ''dense states'' of the layer) and the repulsive loop-loop interactions (which favors the ''dilute states'' of the layer). and (b) show that the AGR approach may provide the basis of a powerful and wide-ranging theory of polymers at interfaces.