Surface relaxation in syndiotactic (st-) and isotactic (it-) poly(methyl methacrylate) (PMMA) films was studied by lateral force microscopy. The αa- and β-relaxation processes were clearly observed even at the surface, permitting us to deduce the form of the dispersion map for the surface relaxation processes. Both relaxation temperatures at the surface were lower than the corresponding ones in the bulk. In addition, the extent to which the peak temperature for the surface relaxation processes fell below that of the bulk strongly depended on the stereoregularity of the films. The differences in the chain conformations between the surface and the bulk, which were more remarkable in the st-PMMA, produced this variation in surface mobility.
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