Adsorption of chain molecules with a polar head a scaling description

TLDR

The study investigates adsorption of chain molecules possessing a polar head attraction and uniform monomer–surface interaction at an interface. A scaling description of chain configurations and interactions is employed to analyze the adsorption behavior. Uniform surface attraction dramatically alters the phase diagram, producing a low‑density two‑dimensional regime and a high‑density confined‑cylinder phase separated by a first‑order transition, with derived power laws for surface density, layer thickness, and surface pressure, and parallels to short‑chain lipids and surfactants suggesting a similar role for uniform surface interactions.

Abstract

The adsorption of chain molecules at an interface is investigated assuming that the molecule has both a polar head type of attraction localized on the chain and a uniform interaction of the chain monomers with the surface. A scaling description of the chain configurations and interactions is used. It is shown that the presence of a uniform surface attraction changes the phase diagram drastically. Both a low density two-dimensional regime and a high density phase with the chains confined in narrow cylinders can occur. The transition between the two phases is first order. Power laws for the surface density, layer thickness and surface pressure are derived. The qualitative similarity with the behaviour observed for short chain lipids and surfactants is also noted and it is suggested that a uniform surface interaction may also play an important role there.