CHAIN PACKING STATISTICS AND THERMODYNAMICS OF AMPHIPHILE MONOLAYERS

In this paper we extend our earlier theories of chain statistics in amphiphilic aggregates to include the important case of surfactant monolayers. Explicitly, the monomer packing conditions are relaxed to allow for the possibility of nonuniform segment densities. Minimization of the chain free energy is carried out under the constraints of inequalities imposed on moments of the conformational distribution function. Results are presented for the segment density and lateral pressure profiles as a function of area per molecule and chain length. We also discuss the computation of surfactant free energies and their relationship to the successive gas → liquid and "expanded liquid" → "condensed liquid" phase transitions in adsorbed monolayers at the air/water interface. © 1990 American Chemical Society.