On two-dimensional ferroelectricity in layered polymer films on substrates

A simple model for describing structural phase transitions in thin ferroelectric copolymer films on solid substrates obtained by the Langmuir-Blodgett method has been suggested. It is shown that the polymer-substrate interaction and surface tension considerably influence these transitions and, in particular, can induce additional low-temperature first-and second-order phase transitions depending on the material parameters and the film thickness. The main dimensionless parameter and its critical value, which control the formation of the additional order in very thin films, are determined.