Polymer Diffusion Under Cylindrical Confinement

Measuring the center of mass diffusion of polymers under confinement is critical for understanding polymer dynamics in applications including semiconductor manufacturing, separation membranes, and polymer nanocomposites. Recent simulations of polymers confined to cylindrical pores reveal non-monotonic changes in the polymer diffusion coefficient, D, as the pore size decreases due to competition between increasing disentanglement and chain segregation. In this study, we use elastic recoil detection to examine the diffusion coefficients of linear polystyrene (M_w = 100-800 kg/mol) confined to cylindrical anodic aluminum oxide (AAO) nanopores (diameter, d = 10-80 nm). The experimental results are compared to the previous coarse grained molecular dynamics simulations to interpret the measured diffusion coefficient in terms of the competition between chain disentanglement and segregation.