Simple interpretative model for the anomalous behavior of the excess surface area in mixed systems with large composition fluctuations: a theoretical analysis and an experimental investigation of mixed phospholipid/omega-3 fatty acid Langmuir-Blodgett films.
We derive an elementary phenomenological lattice hole model to describe the complex behavior of the excess surface area as a function of the composition in two-component monolayers. The model accounts for the coupling between the composition fluctuations and the density (holes) concentration in mixed films. When the composition fluctuations are large and the hole-composition coupling parameters are strong, our model predicts the occurrence of a double maximum (or minimum) in the plot of the excess surface area A(E) against the film composition. The theoretical results are compared with excess surface area measurements of Langmuir-Blodgett films of mixed phospholipid/omega-3 fatty acids performed at different temperature, pH, and pressure.
Raudino
Antonio
A
Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, I-95125 Catania, Italy.
Castelli
Francesco
F
Sarpietro
Maria Grazia
MG