Superlattice model for the elastic properties of polymeric Langmuir-Blodgett films.

Brillouin light scattering measurements of the elastic properties of a family of polymeric Langmuir-Blodgett films have revealed decreasing elastic constants with increasing monolayer thickness. By treating the rodlike backbone molecules which lie in the plane of the surface and the hydrocarbon side chains as separate constituents of a superlattice, these trends have been interpreted and the elastic properties of the constituent layers evaluated. We find that the anomalously small transverse elastic constants of the films are due to the hydrocarbon side chains