In this study

it was examined whether the dynamics of polymer chains at a surface is different from that in thebulk

and if so

to what extent they differ in terms of surface glass transition temperature and diffusion coefficient. Obtainedresults clearly indicate that surface chains can travel for a relatively large distance in comparison with the characteristiclength scale of usual segmental motion even at a temperature below its bulk glass transition temperature

Tgb. This isconsistent with our previous results that the surface glass transition temperature is much lower than the correspoding Tgb.Also

it was experimentally revealed that there was a gradient of molecular motion in the surface region.