  We simulate entangled linear polymers in free-standing thin film geometries
where the confining dimension is on the same scale or smaller than the bulk
chain dimensions. We compare both film-averaged and layer-resolved, spatially
inhomogeneous measures of the polymer structure and entanglement network with
theoretical models. We find that these properties are controlled by the ratio
of both chain- and entanglement-strand length scales to the film thickness.
While the film-averaged entanglement properties can be accurately predicted, we
identify outstanding challenges in understanding the spatially resolved
character of the heterogeneities in the entanglement network, particularly when
the scale of both the entanglement strand and the chain end-to-end vector is
comparable to or smaller than the film thickness.
