Modeling sub-continuum effects on the mechanical properties of ultrathin macromolecular layers

This paper makes progress on the prediction of mechanical modulus and mechanical relaxation time of macromolecular materials at small length and time scales. Fundamental studies of large molecules in confined geometries inform predictions of macroscopic materials behavior. A modified Einstein relation, for diffusion of small particles relates macromolecular monomer and chain lengths to mechanical properties. Measurement of viscosity in thin polymer layers show marked increase in viscosity in polymer layers thinner than the polymer radius of gyration. This modeling enables analysis of measurements of the near zero shear rate viscosity in thin macromolecular layers. The intermolecular diffusion time constants, which also depend upon macromolecular size and confinement effects, govern the mechanical relaxation time. This work aims to connect fundamental macromolecular physics with nanometer-scale process and device development.