SURFACE THERMOMECHANICAL AND GLASS-TRANSITION TEMPERATURE-MEASUREMENTS OF POLYMERIC SOLIDS

The surface molecular motion of polymeric solids was investigated on t he basis of scanning force microscopic and temperature-dependent X-ray photoelectron spectroscopic measurements. The surface of the monodisp erse polystyrene films was in a glass-rubber transition state even at 293 K in the case of number-average molecular weight less than ca. 30k . The surface glass transition temperature, Tgs for the symmetric poly (styrene-block-methyl methacrylate) diblock copolymer films were much lower than those for the bulk samples. A remarkable depression of Tg a t the air-polymer interface was explained by the surface localization of chain end groups.