Wj. Orts et al., OBSERVATION OF TEMPERATURE-DEPENDENT THICKNESSES IN ULTRATHIN POLYSTYRENE FILMS ON SILICON, Physical review letters, 71(6), 1993, pp. 867-870
The temperature dependent thicknesses of ultrathin polystyrene films u
nder vacuum on Si(111) substrates were investigated via x-ray reflecti
vity in situ. The contraction of ultrathin polymer films was directly
observed for the first time to the authors' knowledge. The degree of c
ontraction depends on the initial thickness of the ultrathin polystyre
ne film, with the magnitude of contraction increasing with decreasing
initial film thickness. This contraction ranged from 0%-17% and occurr
ed at temperatures well below the reported bulk polystyrene glass tran
sition temperature.