Surface viscoelastic behaviour of polymeric Langmuir monolayers (original) (raw)

Viscoelastic behaviour in Langmuir monolayers of a photosensitive polyacrylate is investigated by a combination of surface quasielastic light scattering, and a new technique, which we call oscillating needle surface rheometry (ONR). The compressional modulus is determined over several time scales as a function of surface density and temperature, in the cis and trans conformations of the azobenzene side chain. Our results indicate that polymeric monolayers confined at the air-water interface provide interesting model systems for the study of glass transition phenomenology in a strongly confined two-dimensional geometry, without the hindrances to the glassy dynamics imposed by the more common two-dimensional confinements obtained by the deposition of a molecular layer onto a solid substrate.