Groupe de Physique Statistique

Molecular Dynamics studies of simple models (short non-entangled polymer chains and a binary Lennard-Jones mixture) of glassing fluids confined between various types of walls are discussed, with an emphasis on the understanding of the nature of the glass transition from the analysis of confinement effects. Particularly attention is paid to the possible conclusions on a characteristic length that grows, as the glass transition is approached. Particulary useful is the analysis for the local relaxation time $\tau(z)$, $z$ being the distance from the closest confining wall. Both smooth and rough walls are considered (the latter are constructed such that there is almost no layering effect). In all cases it is found that the characteristic lengths do increase with decreasing temperature, albeit rather slowly; the relevance of these lengths for the slowing down near the glass transition remains doubtful.