Thickness Induced Structural Changes in Polystyrene Films

Changes to the structure of polystyrene melt films as measured through the spectrum of density fluctuations have been observed as a function of film thickness down to the polymer radius of gyration ({R}_{g}. Films thicker than 4{R}_{g}show bulklike density fluctuations. Thinner films exhibit a peak in S(q)near q=0which grows with decreasing thickness. This peak is attributed to a decreased interpenetration of chains resulting in an...