Dynamics of Glassy Polymer Melts in Confined Geometry: A Monte Carlo Simulation

Dynamic properties of a dense polymer melt confined between two hard watts are investigated over a wide range of temperatures by dynamic Monte Carlo simulation. The temperature interval ranges from the ordinary Iiquid to the strongly supercooled melt. The influence of temperature, density aud confinement on the polymer dynamics is studied by vanous mean-square displacements, structural relaxation functions and quantities derived from them (relaxation limes, apparent diffusion coefficients, monomer relaxation rates), yielding the folIowmg results: The motion of the monomers and polymers close to the waI1s is enhanced in parallel, but reduced in perpendicular direction. This dynamic anisotropy strongly mcreases during supercooling and extends into the bulklike mner region of the film over a Iength scale which is Iarger than the bulk radius of gyration at Iow temperatures. However, the absolute freezmg of the melt occurs in each Iayer at the same temperature for both the parallel and the perpendicular direction.