ENHANCEMENT OF FUNCTIONAL PROPERTIES OF LANGMUIR FILMS OF POLY(ETHYLENE OXIDE) BY INCORPORATION OF SILICA NANOPARTICLES

One of the most important techniques to improve the functional properties of organized molecular films is to introduce nanometer-size solid particles into them. The Langmuir balance has proved to be useful for controlling and modifying these films by organizing molecules into highly ordered structures. Our aim is to study the efficacy of this technique to improve the compactness of biocompatible polymer films by incorporating nanosilica particles. The experimental technique consists of first adsorbing the polymer on silica particles in an aqueous medium, followed by preparation of a monolayer at the air-water interface in a Langmuir balance. The film is organized by repeated expansion and compression. The surface pressure-surface area characteristics are recorded during each cycle. The pressure of the film increases with decrease in the mean molecular area, but reaches a plateau, probably due to instability of the film. With repeated cycling, the plateau pressure increases indicating that the film has become more stable and rigid. The cycling is continued till plateau pressure does not change with further cycling. The amount of the polymer loaded on the subphase and the ratio of PEO to silica in the film, on the plateau pressure has been studied. A substantial increase in the stability and rigidity of the film is achieved by this technique.