Replication Data for: Anisotropy and anharmonicity in polystyrene stable glass

We have used ellipsometry to characterize the anisotropy in stable polymer glasses prepared by physical vapour deposition. These measurements reveal birefringence values (as measured by the magnitude of in-plane versus out-of-plane refractive index) less than 0.002 in vapour deposited polystyrenes with N from 6-12, and with fictive temperatures below the Tg values from 10 to 35 K. These are the first stable glass materials with demonstrated isotropy over a wide range of experimental parameters. We have measured the thermal expansivity of these stable glasses, and compared to ordinary glass. The thermal expansivity of the stable glasses is less than that of ordinary glass with a difference that increases as the fictive temperature Tf decreases.